Recent advances of boronate affinity materials in sample preparation

Analytica Chimica Acta 1076 (2019) 1e17

Contents lists available at ScienceDirect

Analytica Chimica Acta journal homepage: www.elsevier.com/locate/aca

Recent advances of boronate affinity materials in sample preparation Yang Chen a, b, Ailan Huang a, Yanan Zhang b, Zijun Bie a, * a b

Department of Chemistry, Bengbu Medical University, 2600 Donghai Avenue, Bengbu, 233000, China School of Pharmacy, Bengbu Medical University, 2600 Donghai Avenue, Bengbu, 233000, China

h i g h l i g h t s

g r a p h i c a l a b s t r a c t


This review focuses on boronate affinity material for sample preparation.
The review covers various types of advanced boronate affinity materials.
The review surveys publications on practical applications of boronate affinity materials for sample preparation.
Critical reviews of synthetic strategies and practical use of boronate affinity materials were provided.

a r t i c l e i n f o

a b s t r a c t

Article history: Received 14 December 2018 Received in revised form 18 April 2019 Accepted 19 April 2019 Available online 24 April 2019

Boronate affinity materials, as widely used sorbents for the enrichment of cis-diol-containing molecules, have been rapidly developed and increasingly utilized for various applications in recent years. cis-Diolcontaining molecules, including saccharides, nucleosides, catecholamines, glycans and glycoproteins/ glycopeptides, are major targets in the frontiers of many research areas, such as environmental analysis, the food industry and bioanalysis. As the analysis of these molecules usually suffers from the low abundance of targets and the high abundance of interference, selective enrichment is a fundamental step of sample preparation before analysis. In this review, we survey recent achievements of boronate affinity materials and their applications in sample preparation. We mainly focus on the fundamental considerations of materials as well as important applications in the past 3 years. Particularly, the effects of the substrate structure on the performance of boronate affinity materials, such as binding capacity, affinity, selectivity and working pH, will be discussed. Furthermore, the applications in sample preparation will also be introduced, with a main emphasis on what merits can be provided by boronate affinity materials to overcome the challenges in sample preparation. © 2019 Elsevier B.V. All rights reserved.

Keywords: Boronate affinity Advanced material cis-Diol-containing molecules Sample preparation

1. Introduction cis-Diol-containing molecules are a class of molecules of great academic importance in current research frontiers, including environmental analysis, food industry and bioanalysis. Saccharides,

* Corresponding author. E-mail address: [email protected] (Z. Bie). https://doi.org/10.1016/j.aca.2019.04.050 0003-2670/© 2019 Elsevier B.V. All rights reserved.

nucleosides, catecholamines, glycans and glycoproteins/glycopeptides are typical cis-diol-containing molecules that receive intensive research attention. However, the analysis of cis-diol-containing molecules of analytical importance usually suffers from a low abundance of targets and a high abundance of interference. Thus, selective enrichment is an irreplaceable step in sample preparation before the analysis of cis-diol-containing molecules. Due to their unique binding property towards cis-diol-containing molecules, boronate affinity materials have increasingly attracted attention

2

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

during the past 10 years [1e3]. The history of boronate affinity starts in 1838, when Biot made the first discovery of the interaction between boric acid and cis-diols [4]. However, during the next century, the usefulness of boronate affinity has not been well explored. Only a few references reported the analysis of carbohydrates via boronate affinity [5e7]. In 1970, Weith employed boronic-acid-functionalized cellulose for the chromatographic separation of standard mixtures of ribo- and deoxyribonucleosides for the first time [8]. Following the first boronate affinity material, several boronic-acid-modified chromatographic media were reported within the next four decades [9e12]. Since entering the 21st century, boronate affinity materials have increasingly garnered regard due to the rapid development of related research areas, particularly the x-omics. To date, a large variety of novel boronate affinity materials including porous materials [13,14], magnetic materials [15], polymer brushes [16e20], molecularly imprinted materials [21e23] and graphene oxide [24,25] have been reported for the separation and analysis of various cis-diol-containing compounds, such as nucleosides, nucleic acids, catechols, carbohydrates and glycoproteins/glycopeptides. The binding affinity of boronate affinity materials stems from the reversible molecular interactions between boronic acid ligands and cis-diols. As shown in Fig. 1, boronic acid and cis-diols can form cyclic esters in a basic environment (usually the pKa < environmental pH). The other direction of this reversible reaction happens when the environment changes to acidic, which leads to the dissociation of the cyclic ester. The performance of boronate affinity materials in sample preparation is closely related to their binding properties, particularly the binding pH, affinity, selectivity and capacity. Certainly, the binding properties, such as binding pH and affinity, of boronate affinity materials are associated with the boronic acid ligands. To this end, Liu made a sound and systematic investigation of this relationship [26,27]. However, the structure of supporting materials also has nonnegligible effects on the performance of boronate affinity materials. In particular, the merits of different types of materials should be analyzed and summarized, in order to employ the appropriate materials to meet the various requirements of sample preparation. Clearly, a summary of reported boronate affinity materials will greatly benefit the development and applications of boronate affinity materials. In this review, we try to not only give insights into the preparation of boronate affinity materials but also provide practical instructions for the sample preparation of cis-diol-containing molecules. To this end, we survey recent (past 3 years) established sample preparation procedures for boronate affinity materials. Especially, the preparation of these advanced sorbents and their application in the extraction of some typical analytes from complex samples, including environmental, food and biofluid samples, will be discussed in a comprehensive and systematic way. Additionally, special emphasis will be placed on which merits can be provided by different boronate affinity materials to overcome challenges in the sample preparation. 2. Fabrication of boronate affinity materials A typical boronate affinity material is constructed by combination of a supporting material core and the boronic acid ligands. As

Fig. 1. Interaction between boronic acids and cis-diol-containing compounds.

discussed above, both the structure of the ligands and supporting material have equally important effects on the binding properties of boronate affinity material. To achieve a better performance in sample preparations, different types of boronate affinity materials with certain binding properties should be employed, including the chromatographic stationary phase, mesoporous materials, magnetic nanoparticles, polymer brushes, molecularly imprinted materials and graphene oxide. To satisfied different analytical purposes in sample preparations, different synthetic strategies for various boronate affinity materials should be employed. Up to now, there are two main fabrication strategies of the boronate affinity material. The first strategy is based on the concept of postmodification. With the reaction of the active groups between boronic acid and supporting material, the conventional material could be converted into boronate affinity material. Although this strategy is straightforward and convenient, it might lead to the loss of intrinsic properties of some advanced material (eg. porous structure). Thus, this strategy is suitable for nanoparticles or spherical stationary phase. To avoid the above mentioned problems, the boronic acid appended monomers were introduced into the synthetic procedure in the second strategy. Thus, this strategy is especially applicable for advanced material, such as mesoporous material and molecularly imprinted material. However, the synthetic procedure of boronic acid appended monomer could be complicated and time consuming. Besides, the employment of appended monomer might also result in the further optimization of the synthetic condition of the original material. 2.1. Chromatographic stationary phase In 1970, the boronate affinity material was employed as the stationary phase for the chromatographic separation of nucleosides for the first time. Since then, boronate affinity materials have been widely used as the stationary phase in affinity chromatography for the separation of cis-diol-containing molecules. In the past decades, the emergence of x-omics has amplified interest in the selective separation of certain classes of compounds including nucleosides, glycoproteins/peptides and neurotransmitters. This trend has also mirrored the increasing requirements for novel stationary phases with both high efficiency and simplified operation procedures. Without a doubt, the most convenient way to obtain a boronate affinity chromatographic stationary phase is through a supplier. Although there are some commercially available sorbents [28e30] (Boronic Acid Gel® from Thermo Fisher Scientific and m-aminophenylboronic acid-agarose from Sigma-Aldrich), they still suffer from apparent drawbacks, such as a high working pH (>9) and a low binding capacity (<100 mg/mL). Generally, the boronic-acid functionalization procedure for chromatographic stationary phases can be categorized into two routes: (1) postmodification and (2) “one-pot” approaches. For postmodification, the presence of reactive sites on the surface of the materials is important. Considering silica particles are the most widely used stationary phase, it is very convenient to functionalize the surface with X-silanes (X ¼ amino, azide, or epoxy). After surface functionalization, commercially available boronic acids, such as aminophenylboronic acid, mercaptophenylboronic acid and carboxyphenylboronic acid (Fig. 2), could be easily tethered onto the silica particles via simple chemical reactions. Because of the diversity of X-silanes and boronic acids, the postmodification approach has proven to be readily applicable to a large variety of stationary phases. However, multistep postmodifications lead to time-consuming synthetic procedures. Furthermore, the binding capacity of the material might be affected by the efficiency of the postmodification (heterogeneous liquid-solid reaction).

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

3

Fig. 2. Structure of representative commercially available boronic acid ligands with active groups.

Conversely, the “one-pot” approach is a common synthetic route for monoliths. In a typical procedure, the boronic-acid ligands participate in the copolymerization and directly generate the boronate affinity monoliths. Despite the potential of the “one-pot” approach to greatly simplify the preparation procedure, it requires specific boronic acids with active groups (e.g., vinyl and amino groups). Many efforts have been made to improve the performance of the boronate affinity chromatographic stationary phase [31e35]. By using amorphous silica as the substrate, the 3aminophenylboronic-acid-modified stationary phase was synthesized [36]. The author claimed that the adsorption equilibrium could be reached within a very short time (10 s) due to the structure of the amorphous silica. Li combined a self-designed and synthesized novel boronic acid ligand (4-carboxy-benzoboroxole) with polyethyleneimine (PEI) to prepare a boronate affinity silica stationary phase [37]. The obtained stationary phase showed excellent selectivity (100-fold interference), high binding capacities (88.3 mmol/g for adenosine, pH 7.0) and the lowest binding pH (4.0 for cytidine and as low as 2.24 for xanthosine). To further expand the applications of the boronate affinity stationary phase, a novel silica-based stationary phase was prepared through the cofunctionalization of a Wulff-type boronic acid and C12 for mixedmode liquid chromatography applications (Fig. 3) [38]. The switch between retention mechanisms was easily realized by adjustment

of the mobile phase constitution, thus, the cis-diol compounds could be selectively captured under neutral conditions in boronate affinity mode and separated effectively in reversed-phase mode. Macroporous monoliths, invented by Hjerten, Svec and Tanaka [39e41], are defined as “continuous stationary phases that form as a homogeneous material in a single piece”. Compared with conventional sorbents, monolithic materials can provide several significant advantages such as ease of preparation, low cost and fast convective mass transfer, which favor the application of monolithic sorbents in sample preparation [34,42e44]. To take advantage of the monoliths, hierarchical porous polymers were synthesized via a Pickering high internal polymer emulsion (HIPE) template [43]. Based on this strategy, the boronic-acid-functionalized nanoparticles could not only provide boronate affinity but also serve as the stabilizer for the emulsion system, which led to the good permeability and mechanical properties of the obtained sorbent. The sorbent was also expected to exhibit a high adsorption capacity and fast binding kinetics, due to the special mesopore-inmacropore structure. Under optimized conditions, the binding capacity of this monolithic sorbent could reach 177.8 mmol/g within 2 h under the neutral condition. Most of the reported studies on macroporous monolithic stationary phases have focused on the development of novel monolithic columns for on-line analysis. Liu made tremendous contributions to promote the preparation and applications of

4

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

Fig. 3. (A) Synthesis route of C12-Wulff-PBA silica stationary phase. (B) Reversible capture/release of the cis-diol compounds. Reproduced from ref. 38 with permission from Elsevier.

advanced boronate affinity monolithic columns [27]. Currently, boronate affinity monolithic columns have found wide application in sample preparation [45e48] with their improved chromatographic resolution, higher efficiency, lower sample consumption, more convenient online coupling to mass spectrometry (MS) and improved mass-detection sensitivity. For example, based on the poly-VPBA-EGDMA monolithic column, an on-line solid-phase microextractionehigh-performance liquid chromatography (SPMEeHPLC) system was established for the analysis of nmollevel catecholamines in urine samples [49]. Noticeably, the majority of recently published papers have dealt with organic monolithic columns [46e50]. The most reasonable explanation for this tendency is that the preparation of the organic monoliths are simple and facile compared with that of their inorganic counterparts. Considering the merits of inorganic monoliths, such as a good solvent resistance to swelling, high mechanical stability and high permeability, that are beneficial to the applications of the monoliths, organic-inorganic hybrid monolithic columns have been prepared and used in sample preparation [51,52]. Lin and coworkers first reported a phenylboronic acid-silica hybrid monolithic column using a “one-pot” approach [53]. Taking this hybrid column as the enrichment sorbent, an on-line SPME-LC-MS/ MS method was employed to comprehensively profile nucleosides and ribosylated metabolites in human urine [52]. Poor signal response of the analyte is one of the obstacles we might encounter during analysis. Derivatization was commonly employed to overcome this. However, derivatization was also often associated with tedious procedures and low efficiency. To solve this, Feng and coworkers presented a beautiful strategy combining extraction with in situ derivatization [54e56]. As illustrated in Fig. 4 [55], the authors modified an MCX sorbent with 4phenylaminomethyl-benzeneboric acid (4-PAMBA) under a neutral or acidic condition through cation exchange interactions. The resulting boronate affinity sorbent could selectively capture and purify analytes through the boronate-affinity-based extraction. By employing the boronic acid ligand 4-PAMBA as the labeling reagent, the derivatization could be easily realized by eluting the complex (4-PAMBA-analyte) from the sorbent through removal of the ion exchange and hydrophobic interactions.

2.2. Mesoporous materials Mesoporous materials are a unique type of porous material with an ordered mesopore arrangement. Since the first invention of mesoporous silica in 1992 [57], a large variety of mesoporous materials have been prepared [58e60]. The first boronate affinity mesoporous material was developed by Lu in 2009 [61], and the boronate affinity mesoporous silica was used for the selective enrichment of glycopeptides prior to MS analysis. Since then, the merits of mesoporous materials in sample preparation have been realized by researchers. To fully demonstrate the usefulness of mesoporous materials, a large variety of mesoporous materials have been employed for sample preparation, including spirally curved mesoporous silica nanofibers [62], mesoporous-silicacoated polysulfone capsules [63], mesoporous-silica-coated filter paper [64], graphene/mesoporous silica composites [65] and so on. Until now, boronate affinity mesoporous silica was prepared by grafting. Grafting refers to the subsequent modification of the inner surfaces of mesostructured silica with organic groups. This process is carried out primarily by reaction with the free silanol groups of the pore surfaces. In principle, boronic acid functionalization could be realized in this fashion by the reaction between surface organic groups and boronic acid ligands, as discussed in section 2.1. However, this method of modification has the disadvantage that grafting is usually accompanied by a certain reduction in the porosity of the boronate affinity material. In other words, the mesostructure of the original mesoporous silica might be partially lost. Although there have been alternative functionalization methods for mesoporous silica that could avoid this situation, such as cocondensation and bridged organosilica, they have not been applied to the preparation of boronate affinity mesoporous silica, because special design and synthesized boronic acid functionalized silanes are needed for both methods. Unfortunately, such silanes are not commercially available yet. The high surface area derived from the porous structure is the most significant feature of mesoporous materials. The higher the surface area is, the higher the binding capacity that can be achieved. Thus, the employment of mesoporous sorbents in sample preparation will not only improve the recovery of the analytical

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

5

Fig. 4. General principle of the in situ derivatization of BRs. Reproduced from ref. 55 with permission from American Chemical Society.

method but also expand its linear range. For instance, because of the high surface area of mesoporous silica (570 m2/g), magnetic polysulfone capsules coated by phenylboronic-acid-functionalized mesoporous silica nanoparticles possessed an enhanced capacity and selectivity that were distinctly better than those of noncoated ones [63]. The equilibrium time of adsorption/desorption is one of the key aspects of the sample preparation. Fortunately, the fast mass transfer derived from the ordered porous structure will lead to fast absorption/desorption kinetics. Thus, the equilibrium time of mesoporous materials could be significantly shortened compared with that of conventional materials. To take advantage of this, a magnetic graphene/mesoporous silica composite was prepared for antibiotics residue analysis [65]. Compared to the properties displayed by the majority of the other reported methods, this material presents not only similar recoveries, precisions and linearity ranges but also a significantly shortened sample-pretreatment time (10 min vs 70 min). Another significant feature of mesoporous materials is the molecular sieve effect derived from orderly mesopores with limited pore sizes. As shown in Fig. 5, the synthesized novel hydrophilic probe (Fe3O4@m-SiO2@G6P) demonstrated the molecular sieve effect vividly [66]. The hydrophilic probe inside the pores could only interact with the small-size peptides that went into the mesochannels, while the large-size proteins were simultaneously excluded outside. The elimination of the suppression effect of interferences greatly improved the mass spectrometric (MS) detectability of this method. The LOD of this approach was decreased to merely 0.5 fmol/mL, which was substantially lower than previous reports [67]. The tolerance for interference could also be strengthened by molecular sieve effect. Even with a 1000-fold interference of proteins, this method was still valid. Apart from mesoporous silica, a few attempts to employ other

types of boronic-acid-functionalized mesoporous materials have been made [68e70]. Polyhedral oligomeric silsesquioxanes (POSS) are a kind of nanosized building blocks for the synthesis of microporous/mesoporous materials [68]. The facile tailorability in virtue of the residual vinyl groups has been greatly utilized in the synthesis. By using vinyl chemistry, boronic acids were grafted onto the surface via a one-step free-radical polymerization. The obtained Fe3O4@POSS-AAPBA possesses a porous structure with a high surface area and high density of the functional boronic acid ligands. Furthermore, this method was significantly more sensitive for the detection of catecholamines (CAs) (0.81e1.32 ng/mL), which will greatly benefit its applications for biological analysis. Metal-organic frameworks (MOFs) are highly crystalline and porous compounds. Although, MOFs do not belong to mesoporous materials, they do share some similar merits such as a porous structure and high surface area. The first example of boronate affinity MOFs was presented by Gu and coworkers [71]. By substituting the original organic linker in MIL-100 (1,3,5-benzene tricarboxylic acid, BTC) with BBDC (5-boronobenzene-1,3dicarboxylic acid), the authors synthesized boronic acid suspended MOFs (MIL-100-B). To explore more applications of this novel material, MIL-100-B was employed as a nanoreactor for the solid phase orientation labeling of carbohydrates [72]. As a result, this novel approach presented several merits, including a high separation efficiency (almost all of the incorporated boronic acid groups were available), a rapid labeling reaction speed (the labeling reaction time was decreased from 7 h to 3 min), a high purity of the product and a three orders-of-magnitude lower applicable carbohydrate concentration for labeling. By using the synergy of the “molecular sieving effect” of MOFs and the specific molecular recognition of boronic acids, porous carbon materials decorated with a boronate affinity MOF membrane was reported for luteolin analysis in the aqueous phase [70].

6

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

Fig. 5. Synthetic procedure of Fe3O4@mSiO2@G6P probe. Reproduced from ref. 66 with permission from Elsevier.

2.3. Magnetic nanoparticles Nanoparticles, with their relatively simple synthetic procedure compared with that of mesoporous materials, have attracted great attention among analytical chemists [73,74]. In particular, magnetic nanoparticles (MNPs) were one of the most commonly used sorbents in sample preparation, due to their feasible recovery by means of external magnetic fields. However, bare MNPs exhibit a high adsorption efficiency for most compounds through specific and nonspecific interactions. For real-world applications, highly selective MNPs are desirable for sample preparation procedures. Due to the merits brought by the combination of boronic acid and MNPs, boronate affinity MNPs have recently become a hotspot in the highly efficient separation and molecular recognition of cisdiol-containing biomolecules in complexes [75e77]. To decorate MNPs with boronic acids, several approaches could be employed. Postmodification is the most commonly used approach [78e84]. Click chemistry, including CuAAC and thiol-ene

click reactions, has found numerous applications in postmodification due to the high yield of the reaction. Through thioleene click reactions, a series of boronic-acid-functionalized Fe3O4 MNPs were synthesized [79]. The resulting MNPs exhibited excellent specificity and a high binding capacity towards glycoproteins (777.9 mg/g for OVA and 145.7 mg/g for Trf). The greatly enhanced adsorption capacity towards glycoproteins indicated that the “click” method presented great superiority in ligand immobilization. As discussed above, the surface of MNPs were modified with boronic acid ligands through one-/multistep chemical reactions. Although these synthetic procedures proved to be effective, they still suffered from some drawbacks such as being time-consuming. To overcome this, Chen presented a facile and time-saving method to synthesize boronate affinity MNPs using a distillationprecipitation polymerization (DPP) technique [86]. As shown in Fig. 6, the polymer shell was obtained through the copolymerization of an affinity ligand (3-acrylaminophenylboronic

Fig. 6. Scheme for the synthesis of Fe3O4@P(AAPBA-co-monomer)NPs. Reproduced from ref. 86 with permission from American Chemical Society.

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

acid) and a hydrophilic functional monomer (2-hydroxyethyl methacrylate, HEMA). The resulting hydrophilic Fe3O4@P(AAPBAco-HEMA) NPs assisted in improving the separation due to synergistic forces, such as hydrophilic, electrostatic interactions and boronate affinity. Thus, the material exhibited a high adsorption capacity (220 mg/g) and excellent specificity (100-fold interfering) towards glycoproteins at pH 9.0, even in the physiological environment (pH 7.4). Furthermore, the preparation of coreeshellstructured boronate affinity MNPs represented a simpler synthetic procedure. As reported by Lin [87], coreeshell boronate affinity MNPs were prepared using the hydrolyzed tetramethyloxysilane (TMOS) and 3-methacryloxypropyltrimethoxysilane (g-MAPS) as coprecursors, 4-vinylphenylboronic acid (VPBA) as a functionalized monomer, and ethylene glycol methacrylate (EDMA) as a crosslinker. This one-pot synthesis simultaneously realized boronic acid functionalization and surface modification. Due to the surface modification, the core-shell MNPs exhibited an excellent selectivity and good biocompatibility [85]. More importantly, it is reasonable to assume that if more binding sites could be provided by the MNPs, then the adsorption capacity should be further improved. With the aim of increasing the binding sites of MNPs, one solution involved preparing MNPs with a smaller size, thus providing a larger surface area for active site binding [88,89]. Additionally, the addition of branched polymers onto the surface of MNPs could provide numerous binding sites and serve as a scaffold to support selective enrichment. For example, the abundant amino groups of polyethyleneimine (PEI)-coated MNPs provided adequate binding sites for boronate ligands, and the resulting nanoparticles presented a large adsorption capacity (3.45 mg/g for epinephrine, two-times larger than that of commercial products) and excellent selectivity towards cis-diol-containing compounds [83]. Another more effective and attractive choice is to form nanocomposites of MNPs with other components that offer a larger surface area. In the meantime, the magnetic susceptibility of MNPs could also simplify the manipulation procedures of the magnetic hybrid nanocomposites during sample preparation [70,90,91]. For instance, a novel boronate affinity magnetic hybrid nanocomposite (denoted as Fe3O4/ZIF-8/APBA) was prepared [91]. This nanocomposite inherited the high surface area from ZIF-8 and the superparamagnetic nature from the Fe3O4 MNPs. Thus, this nanocomposite was able to conveniently separate glycoprotein from real samples with a high adsorption capacity (up to hundreds mg/g) and specific recognition (LOD of 10 ng/mL). Pan presented another example of the combination of a teamed boronate affinity (TBA) material with MNPs [90]. By virtue of Fe3O4@PGMA-TBA/MIPs, the authors successfully enriched target glycoproteins from practical samples at physiological pH. 2.4. Polymer brushes Polymer brushes are special macromolecular structures with polymer chains densely tethered to a substrate (1D-polymer chain, 2D-surface, 3D-spherical) via chemical-bond linkages. The introduction of polymer chains onto the substrate will not only significantly change the surface properties of the substrate but also endow the obtained hybrid polymer brushes with new functionalities. Thus, polymer brushes are of great interest in the field of analytical science due to their extensive range of applications [92]. Polymer brushes can be prepared by living/controlled polymerizations. Among these methods, atom transfer radical polymerization (ATRP) is the most widely used because of its mild reaction conditions, versatile control of the polymer structure and compatibility with a broad range of monomers [93e95]. In conjunction with a simple postmodification with boronic acid,

7

polymer brushes made by ATRP have easily been converted into boronate affinity materials for sample preparation [96e100]. Wei and coworkers reported the first example of a polymeric brushboronate affinity adsorbent via SI-ATRP [101]. With the help of a readily accessible high density of functional groups on the surface of the brush, the binding capacity reached 736.8 mmol/g for fructose, which was substantially higher than the values of other boronate affinity materials. Additionally, the authors also demonstrated a relationship between the binding capacity and the ATRP conditions. It is important to point out that most of the reported boronic acid functionalizations were achieved via click chemistry, which is only applicable to boronic acid ligands with specific reactive groups (vinyl and alkynyl, Fig. 2). To solve this, Zhang incorporated gold nanoparticles with polymer brushes (poly(acryloyloxyethyltrimethyl ammonium chloride)), which were located on the exterior of attapulgite [98]. In this approach, 4mercaptophenylboronic acid could be modified through an AueS bond. Due to the high density of the cationic polymer grafted onto the surface of the attapulgite, more gold nanoparticles could be deposited, which further increased the surface area of the material. Thus, a superior adsorption capacity (30.83 mg/g for nucleosides) and high selectivity (1000-fold interferences) could be achieved. However, the incorporated gold nanoparticles might be lost during the experimental procedure, which would lead to declines in reproducibility and binding performance. As a modified polymer chain could dramatically change the surface properties of a material, polymer brushes are one of the most commonly used stimuli-responsive materials. As depicted in Fig. 7, Ye developed a novel dual stimuli-responsive nanostructured core-brush composite, Si@pNIPAm-b-pBA, via the combination of SI-ATRP and click chemistry for bioseparation [102]. The nanocomposite could retain a high binding capacity, even at physiological pH. The pNIPAm segment in the copolymer brushes served as an intelligent “spring” to tune the structure of the polymer brushes, thus, regulating the binding capacity towards glycoproteins. Ye and coworkers also made a sound investigation of the structure-function relationship of the boronate affinity polymer brushes [96]. Based on their results, the authors found that boronic acids that were located at the chain termini (outer) of the polymer brushes contributed most to the binding. They also demonstrated that it was possible to use temperature to control the target binding and release. However, we should acknowledge that polymeric brushes are a soft material, and the boronic acid ligands at the chain termini (inner) of the polymer brushes might suffer from possible stereo-hindrance effect. All these concerns should be taken into account during the design of novel boronate affinity polymer brushes for various purposes in sample preparation. More binding sites is another merit that the polymer brushes could provide. The increased number of binding sites will not only improve the binding capacity but may also lead to a high affinity due to the synergistic multiple binding effect. This particular characteristic will be greatly beneficial to the analysis of trace targets. Considering this advantage, Liu employed highly branched dendrimers to amplify the number of boronic acid moieties for the first time. The obtained material exhibited a dramatic enhancement (3e4 orders of magnitude) in the boronate affinity compared with that of conventional materials [103]. Inspired by this result and by using dendrimeric poly(amidoamine) (PAMAM) [104], branched polyethyleneimine (PEI) [105e108] or tris(2-aminoethyl)amine [109], a series of boronate affinity materials were prepared. For example, the PEI-assisted boronic-acid-functionalized magnetic nanoparticles exhibited a high binding affinity towards glycoproteins with dissociation constants of 106-107 M and an LOD for glycoproteins as low as 2  1015 M [106].

8

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

Fig. 7. Preparation of Si@pNIPAm-b-pBA core-brush nanocomposite via the combination of SI-ATRP with CuAAC click reaction, and the schematic of glycoprotein binding to the boronic acid-functionalized polymer brushes. Reproduced from ref.102 with permission from American Chemical Society.

2.5. Molecularly imprinted material Despite the evidence that boronic acid ligands can provide a unique affinity towards cis-diol-containing molecules, boronate affinity sorbents continue to face extra challenges when dealing with complex matrices. A competitive binding affinity towards interfering compounds would lead to a decline in performance. Therefore, highly selective sorbents are in great need for the sample preparation of complex matrices. Molecularly imprinted polymers (MIPs) [110,111] are chemical receptors synthesized in the presence of a template. Due to the presence of nanoscale imprinted cavities, which are highly complementary to template molecules, molecularly imprinted materials can provide antibody-like binding specificity and affinity towards target analytes. Boronate affinity molecular imprinting is a covalent imprinting approach, which utilizes readily reversible condensation reactions of boronate esters to generate adducts of functional monomers and templates in the molecular imprinting process. Because of the likelihood of site heterogeneity in conventional imprinting, the developed boronate affinity imprinting methodology can yield a more homogeneous binding-site distribution due to the greater stability of covalent bonds over that of noncovalent bonds. In boronate affinity imprinting, the role of the boronic acid monomer is to provide functional groups that can form a complex with the template by boronate affinity. Until now, many different boronic acid monomers have been used in covalent imprinting, and some representatives are summarized in Fig. 2. For molecularly imprinted materials, there have been three most widely used strategies: bulk imprinting [112,113], beadforming imprinting [114,115] and surface imprinting [116,117]. In many situations with bulk imprinting, the templates, functional monomers and crosslinkers are mixed together, and the mixture is polymerized into a polymer. Then, the product is crushed, ground

and sieved to the appropriate size. For bead-forming imprinting, the technique allows for the direct preparation of imprinted polymer beads through precipitation polymerization, emulsion polymerization or suspension polymerization, avoiding further processing such as grinding and sieving. Clearly, both of the above methods suffer from drawbacks, such as an incomplete template removal, small binding capacity and slow mass transfer, which will further limit the application of the imprinted materials in sample preparation [118]. To solve this problem, a pH-responsive imprinting monomer (2-(dimethylamino) ethyl methacrylate) was employed to prepare a pH-responsive imprinting layer [119]. Due to pH changes in the charge on the imprinting layer, swelling of the obtained material was observed, which would benefit the mass transfer process. Under the synergistic effect of the boronate affinity and swelling-shrinking behavior of the imprinted material, the binding equilibrium was achieved within approximately 10 min. For surface imprinting, the template molecules are first situated at or immobilized on the surface of a solid substrate, and then, the imprinting starts at the substrate surface. Although this strategy allows for the efficient removal of template molecules and provides good accessibility to target molecules, the binding capacity is highly dependent on the specific surface area of the substrate used. Namely, the binding capacity of the imprinted material is low when a low-surface-area substrate is used. On the other hand, special experimental techniques are required to fabricate an imprinting layer on the exterior of a high-surface-area substrate, such as porous materials [118]. To overcome this problem, a delicate imprinting approach called oriented surface imprinting was proposed by Liu and coworkers (Fig. 8) [120]. By virtue of the pHresponsivity of boronate affinity materials, this novel approach was based on the interaction between a boronic-acidfunctionalized substrate and template, rather than the interaction

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

9

Fig. 8. Schematic diagram of boronate affinity-based controllable oriented surface imprinting of glycoproteins. Reproduced from ref. 120 with permission from Royal Society of Chemistry.

between functional monomer and template molecules in conventional methods. Moreover, the template could be easily removed by disrupting the boronate affinity. With these merits, molecularly imprinted boronate affinity materials have found a wide range of applications in sample preparation [121e123]. To achieve a better performance from MIPs, on the basis of the sound understanding of boronate affinity molecular imprinting, Liu and coworkers demonstrated that the thickness of the imprinting layer should be adjusted to 1/3 to 2/3 of the molecular size of the template in one of the three dimensions [21,118]. This imprinting strategy may allow for the nearly complete removal of template molecules, providing good accessibility to target molecules. Another advantage of this approach is that an excess of binding sites on a functionalized solid substrate can be nearly completely covered by the presence of the imprinting coating, which can effectively suppress or even eliminate nonspecific adsorption. On the basis of this strategy, glycanspecific artificial antibodies were prepared through precision imprinting [124]. As shown in Fig. 9, by using glycopeptides as the template and with the help of precision imprinting, the obtained MIP could achieve glycan specificity while excluding the peptide chain from the imprinted pattern. Binding capacity is another critical aspect in the evaluation of the sorbents for sample preparation. There have been attempts to utilize high-surface-area materials with the molecular imprinting strategy. Taking a hollow molecularly imprinted boronate affinity material as an example, polymers achieved 17.29 mg/mg for guanosine, the adsorbed target molecule [125]. This advantage could be attributed to the hollow structure, which provided significantly more binding cavities on the inner and outer surfaces of the material. Another

example involved molecularly imprinted mesoporous silica nanoparticles. The synthesized material was used for the specific extraction of amadori compounds [126]. Thanks to the mesoporous structure, the binding capacity of target amadori compounds reached 45 mmol/g. However, all the reported examples were focused on specific materials, and a general molecular imprinting strategy for porous materials is still lacking. Therefore, future research directed towards this goal is strongly recommended. 2.6. Graphene oxide Graphene oxide (GO) has been considered an ideal substrate for sorbents in sample preparation [127,128] due to its excellent physical and chemical properties. In fact, its two-dimensional structure endows a dominant surface-to-volume ratio, which can accommodate more recognition sites. Apart from the layered structure with a large theoretical specific surface area, GO nanosheets bear hydroxyl and epoxy groups in the graphitic planes and carboxylic acid groups at the sheet edges, which are preferable to achieve further postmodification with aminophenylboronic acid. Numerous attempts have been made to prepare various GO-based nanocomposites, such as monolithic columns [129,130], nanoparticles [131e133], molecularly imprinted materials [134,135] and polymer brushes [136,137]. Li developed an aminophenylboronic acid (APBA)/GO-based hybrid monolithic column for the online SPE of glycoproteins [130]. This novel type of monolithic column with enhanced selectivity towards glycoproteins enabled their isolation from mixtures with a large excess of other proteins (50-fold interferences). This excellent selectivity was attributed to the

Fig. 9. Schematic of the precision imprinting strategy through combining in situ dual enzymatic digestion and the precision imprinting. Reproduced from ref. 124 with permission from American Chemical Society.

10

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

hydrophilic nature of the graphene oxide, which was beneficial to reduce the adsorption of nonglycoproteins. To realize modifications with other boronic acids (different from aminophenylboronic acid), a polymer with reactive sites (such as polydopamine, polyethylenimine and molecularly imprinted polymers) could be coated on graphene oxide. The following functionalization could be achieved by either physical adsorption or chemical reaction. As shown in Fig. 10, Zhang and coworkers presented a sophisticated synthesis strategy for the preparation of Fe3O4/PDA/GO/PEI/CBX nanocomposites [131]. The magnetic Fe3O4 simplified the separation procedure of the nanocomposites. The presence of PDA made the nanocomposites more suitable for the subsequent self-assembly process with PEI. Finally, the PEI, with branched structure, was verified as an excellent scaffold to amplify the number of boronic acid ligands (CBX). The obtained nanocomposites were applied to the enrichment of glycoproteins from human plasma under physiological conditions. Compared to the previous results obtained by other boronate affinity materials [138], the number of identified glycoproteins (137 vs 78) and the enrichment selectivity were improved (67.8% vs 57.8%), and more low abundance and labile glycoproteins were detected (eight more glycoproteins were identified). However, to incorporate so many functionalities into one nanocomposite, a complex multistep synthetic procedure will be inevitable, which might make the preparation laborious.

environmental pollutants, the LOD of the adopted approach is always a priority because most pollutants exist at trace or ultratrace levels. Table 1 lists the detailed application performances of boronate affinity materials with environmental samples obtained in recent years. Particularly, all the LODs were lower than 50 ng/l, which could meet the requirements of environmental analysis. For example, sulfonylureas (SUs), highly effective herbicides, are widely used and commercialized worldwide. Because SU residues in environmental waters might do harm to human beings and aquatic ecosystems, the monitoring of SU residues in the environment is highly desired. Huang and coworkers presented a series of solutions for the analysis of the environmental SU residues [34,139,140]. By using a boronate affinity monolith as the sorbent for SPME, the authors successfully quantified the SU residues in water and soil samples with a satisfactory recovery (70e110%) and RSD (<10%). Nitrophenols, highly noted pollutants of the US Environmental Protection Agency, could also be extracted from water samples by the boronate affinity material [44]. Additionally, the existence of BeN coordination between the sorbent and analytes further promoted the extraction performance for nitrophenols pollutants. Under optimized conditions, the developed method could be used to effectively determine trace nitrophenols in water samples (LOD: 9 ng/L and RSD<9%).

3. Applications

Food security is always a hot-topic in our society. The analysis of food samples contains two major tasks: the strict control of hazardous compounds and the quantitation of nutrients. The former is related to the safety of the food, while the latter determines the effectiveness of the food. To control the presence of hazardous compounds in food, the LOD of the method should meet the corresponding analytical demands. For quantitation, the linear range and recovery are the two key aspects that should be taken into account. Thanks to the development of advanced boronate affinity materials in recent years, all these requirements can be satisfied. In general, boronate affinity materials have found numerous applications in the analysis of different kinds of food samples, such as aloe vera, fruit, mussels, rice, soybean, milk, cigarettes and so on [48,54e56,72,78,121,126,141].

With the rapid development of life science and analytical science, the qualitative and quantitative analyses of cis-diol-containing molecules in the real world are of great importance. Considering the complex matrix effect of real-world samples, sample preparation is a fundamental step in the analytical workflow. As discussed above, substantial effort has been made towards the preparation of various boronate affinity materials with advanced binding properties. These boronate materials are able to overcome the challenging tasks of sample preparation. Based on a survey of the related literature from the past 3 years, the application of boronate affinity materials in sample preparation have mainly focused on three major areas: environmental samples, food samples and biofluid samples. 3.1. Environmental samples The condition of the environment is highly related to public health, thus, the analysis of pollutants in environmental samples is of great importance in our daily life. When dealing with

3.2. Food samples

3.2.1. Hazardous compounds Natural toxins generally exist in low concentrations in complex natural samples, such as grain products and seafood. This fact makes not only the analysis challenging but also the isolation of pure toxins a difficult and tedious process. Azaspiracids, a large group of polyether toxins, are responsible for the intoxication of

Fig. 10. Preparation Procedure of Fe3O4/PDA/GO/PEI/CBX Nanocomposites. PDA: polydopamine, CBX: carboxybenzoboroxole, PEI:polyethylenimine. Reproduced from ref. 131 with permission from American Chemical Society.

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

11

Table 1 Application of boronate affinity materials in sample preparation procedures for environmental samples. Material

Sample

ABA/MMF-SPME

river, lake, well water

Analyte

sulfonylurea herbicides (TRM, THM, MEM, CHS, PRS, HAM) APBDB/SCSE tap, lake, river, waste water nitrophenols (4-NP, 2,4-DNP, 2-NP, 5-M-2-NP, 5-MO-2-NP, 4-TB-2-NP) VBADB/MSPE lake, reservoir water fluoroquinolones (MAR, NOR, CIP, LOM, ENR, SAR, SPA) VPBDB/SCSE river, lake, waste water sulfonamides (SMT, SIM, STZ, SPD, SMD, SCP, SDP, SQA) MBA/MMF-SPME tap, river, waste water sulfonylurea herbicides (THSM, MSM, CS, PS, HSM)

Analytical techniques Linear range

Recovery (%) LODs

Reference

HPLC-DAD

0.5e200 mg/L 70.6e110

0.018e0.17 mg/L

[34]

HPLC-DAD

1e200 mg/L

71.2e115

0.097e0.28 mg/L

[44]

HPLC-DAD

0.5e200 mg/L 72.0e118

0.050e0.12 mg/L

[84]

HPLC-MS/MS

0.05e50 mg/L 72.2e110

0.0012e0.010 mg/L [139]

HPLC-DAD

0.1e200 mg/L 70.1e108

0.009e0.018 mg/L

[140]

ABA: acrylamidophenylboronic acid; MMF: multiple monolithic fiber; APBDB: poly (3-acrylamidophenylboronic-co-divinylbenzene); SCSE: stir cake sorptive extraction; VPBDB: poly(4-vinylphenylboronic acid-divinylbenzene); MBA: monolith-based adsorbent; VBADB: poly (4-vinylphenylboronic acid-co-divinylbenzene); MSPE: magnetic solid-phase extraction.

human shellfish consumers. A boronic-acid-gel packed column was proven to be able to afford the cleanup of azaspiracid-containing mussel extracts, reducing matrix effects in LCMS analysis as well as much of the color [141]. Due to the removal of most interfering peaks in MS, a total of 14 different kinds of azaspiracids were detected. Furthermore, the boronate affinity extraction may also be applicable to numerous other natural toxins, such as trichothecenes, tetrodotoxins, ciguatoxins, and palytoxins. Salbutamol (SAL) is another example of a hazardous compound that needs to be monitored due to its widespread abuse as a feed additive. Considering SAL is a typical 1,3-cis-diol drug, boronate affinity should be a promising strategy for the extraction of SAL. An analytical method for SAL based on the Fe3O4@SiO2@FPBA adsorbent and HPLC was established [78]. This method was successfully applied for the determination of trace levels (0.19 mg/kg) of SAL in pig tissue samples with an acceptable reliability (RSD<2.1%). There are also other examples of boronate affinity materials for the analysis of hazardous compounds (polyphenols and aminoglycosides) in food samples, which are summarized in Table 2.

3.2.2. Nutrients Carbohydrates are the most well-known cis-diol-containing nutrient in food. They are involved in a wide range of biological and pathological processes. The distribution of carbohydrates in food samples is of major interest throughout many areas. However, carbohydrates have poor mass spectrometry spectrum responses, and therefore, they require the appropriate derivation of a signalproducing reagent prior to their qualitative and quantitative analyses [142]. Considering this need, boronic-acid-functionalized Raman-active tags were employed to generate detectable signals of carbohydrates by Liu's group. With this strategy, the authors developed a facile approach, called plasmonic affinity sandwich assay (PASA), for the rapid probing of monosaccharides (glucose and fructose) in plant tissues [123]. The boronate affinity MIP on the extraction microprobes ensured the specificity (10-fold interference), while the plasmon-enhanced Raman scattering (PERS) detection provided a high sensitivity (1 mg/L). Additionally, the whole procedure was fast and straightforward, which required only 20 min for all steps. Brassinosteroids (BRs), endogenous plant growth-promoting hormones, play important roles in plant physiological processes. Their poor ionization efficiency is a major challenge for the accurate analysis of BRs in complex plant samples by mass spectrometry. To this end, Feng developed a series of in situ extraction-derivatization strategies for the detection and determination of BRs in various food samples (Oryza sativa, Arabidopsis thaliana, Brassica napus, and rice) [54e56]. Detailed information about the performance of these methods can be found in Table 2.

3.3. Biofluid samples Most of the cis-diol-containing molecules of biological importance are often associated with possessing a low abundance. The selective enrichment of these biomolecules is the critical step before subsequent analyses. Boronate affinity materials have proven to be an effective enrichment medium for cis-diol-containing biomolecules, such as ovalbumin from the egg white [143,144], nucleosides, catecholamines and glycoproteins from human biofluid [103,145e148]. During the sample preparation of biofluid samples, selectivity and working pH are the top two priorities that affect the performance of boronate affinity materials in the separation and enrichment. Good selectivity is the key to ensure the successful extraction of trace target analytes in the presence of abundant interference. The sample pH value is another important parameter affecting the extraction efficiency because the existing form of biomolecules might be vulnerable to changes in the sample pH. Based on these concerns, we summarize the performance of recently reported applications of boronate affinity materials in the sample preparation for biofluid samples (Table 3). Glycoproteins play important roles in many biological processes such as cell adhesion, signal transduction, immune defense, cell differentiation and embryonic development. Boronate affinity materials have long been used to capture glycoproteins [26,27]. For example, ovalbumin was isolated directly from 2000-fold diluted egg white by using boronate affinity amorphous titania [149]. According to the results of MALDI-TOF MS, the signals of the direct analysis of the egg white sample were weak due to ionization suppression. After extraction by the modified titania, the signal of OVA was clearly identified. However, the sample preparation was conducted under pH 9, and the authors indicated the pH adjustment of the biofluid sample, which might cause potential damage to the analyte. To this end, a temperature and pH dual-responsive core-brush nanocomposite was prepared for enrichment of ovalbumin by Ye [102]. The obtained material could separate OVA directly from the egg white at neutral pH. Owing to their high specificities, boronate affinity MIPs have allowed for the specific extraction of glycoproteins in biofluid samples. Li reported imprinted nanomaterials for the detection and determination of transferrin in human serum [150,151]. By using a more hydrophilic imprinting layer (poly-2-anilinoethanol), the imprinted material exhibited excellent specificity (50-fold interference) and a high binding strength (107 M). In addition, the glycans and glycopeptides were also important targets in glycoproteomics analysis. A new strategy, precision imprinting with alternative templates, for the facile preparation of glycan-specific artificial antibodies was proposed by Liu and coworkers [21,124]. The prepared glycan-imprinted magnetic nanoparticles exhibited a

pig tissues blue mussels plant tissues

rice

plant tissues

Fe3O4@SiO2@FPBA BA-gel BBII modified MCX material

4-PAMBA tips

p(4-VPBA-co-EGDMA) coated Fe3O4@SiO2 mSiO2-SS-PBA nanofiber BA-MOF-PFCS BA-MOF (B-D-MIL-100) BAMNPs BA-MIPs BA-MIP based PASA APBA-MIMSNs

plant tissues peanut shell aloe leaves rice soybean apple cigarette

milk MG@mSiO2-APB

BPPLOT: boronate-decorated polyethyleneimine-grafted porous layer open tubular; BA-gel: boric acid gel; VPBA: vinylphenylboronic; EGDMA: ethylene glycol dimethacrylate; FPBA: 4-formylphenylboronic acid; APBA: aminophenylboronic acid; MIMSNs: molecularly imprinted mesoporous silica nanoparticles; MG: magnetic graphene; APB: 3-aminophenylboronic acid; PBA: 4-mercaptophenylboronic acid; BBII: 2-(4-boronobenzyl) isoquinolin-2-ium; BAMNPs: boronate affinity magnetic nanoparticles; PASA: polymers-based plasmonic affinity sandwich assay; PFCS: porous foam-like carbon substrate; 4-PAMBA: 4-phenylaminomethyl-benzeneboric acid.

[62] [70] [72] [82] [121] [123] [126] e 72.81 mg/g e 27.1 mg/g 0.750e0.882 mg/g e 45 mmol/g 85.3e115.4 e e 70.5e98.2 88.3e105.7 e e 1e100 pg/mL e e 0.2e500 pg 0.01e0.20 mg/mL 1e10000 mg/mL e UPLC-MS UV ESI-MS UPLC-MS/MS HPLC-UV Raman ESI-MS

0.21e0.62 pg/mL e 100 ng/L 0.86e3.48 fg 0.001e0.002 mg/mL 1 mg/L e

[56] 12 mg/g 74.0e116.6 1.0e100.0 pg/mL LC-MS/MS

0.27e1.29 pg/mL

[55] e 82.3e110.5 LC-MS/MS

0.10e10 ng/mL

0.8e5.7 pg/mL

[78] [141] [54] 50.0 mmol/g 50 mg/g 169.6 mmol/g 89.5e108.0 80e90 94.8e116.3 HPLC-UV LC-MS LC-MS

0.32e800 mg/kg e 0.01e10 ng/mL

0.19 mg/kg e 1.4e2.8 pg/mL

[65] e 94.3e108.3 LC-MS/MS

10e3000 ng/mL

2e5 ng/mL

[48] 80.9e101.5 fruit juices BPPLOT

polyphenols (catechin, chlorogenic acid, caffeic acid, epicatechin, ferulic acid) aminoglycosides (streptomycin and dihydrostreptomycin) salbutamol azaspiracids brassinosteroids (BL, CS, TY, 2.8-homoBL, 28-homoCS, 6-deoxoCS) brassinosteroids (BL, CS, 28-norBL, 28-norCS, 28-homoBL) brassinosteroids (BL, CS, 28-norBL, 28-norCS, 28-homoBL, TY, TE) brassinosteroids (BL, 2,4-epiBL, 28-homoBL) flavonoid (luteolin) carbohydrates (glucose, mannose and galactose) brassinosteroids (BL, CS, TY, 6- deoxoCS) flavonoid glucosides (daidzin, glycitin, and genistin) monosaccharides (glucose and fructose) amadori compounds

HPLC-UV

5e100 mg/mL

0.5e4 ng

Binding Capacity LODs Recovery (%) Linear range Analytical techniques Analyte Sample Material

Table 2 Application of boronate affinity materials in sample preparation procedures for food samples.

143e170 mg/m

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

Reference

12

specific affinity towards intact glycoproteins and their characteristic fragments such as glycopeptides. Combined with MS detection, the glycan-imprinted MIPs could be a powerful tool for the efficient identification of glycoproteins (transferrin, alpha 2Heremans-Schmid glycoprotein) in biological samples (human serum). It is worth noting that the above-discussed imprinted materials could still be functional at neutral pH. These results demonstrated the feasibility of boronate affinity MIPs for the affinity separation of glycoproteins/peptides in biofluid samples. As the building blocks of nucleic acids, free and modified nucleosides play an important role in RNA bioactivity. Normal nucleosides exhibit many biological activities, such as anticonvulsant activity and axon growth stimulation. It is therefore important to develop efficient and practical methods for nucleoside enrichment from complex biofluid samples. An effective SPE method based on the combination of a boronate affinity adsorbent with CTAB was established [63]. The CTAB was used to promote the interaction between the analytes and sorbent. With this unique mechanism, the method was proven to be effective in concentrating trace amounts of nucleosides in HepG2 cells incubated with Au NPs. The results showed that Au NPs have a potential toxicity to the nucleoside's metabolism of cells. A boronate-decorated polyhedral oligomeric silsesquioxanes (POSS)-grafted cotton fiber was employed for the extraction of nucleosides in urine [69]. After extraction, a total of five nucleosides (cytidine, uridine, inosine, guanosine, and adenosine) were detected and quantified with good reliability (RSD: 0.7e8.8%). 4. Conclusion and perspectives In the past decade, boronate affinity materials have increasingly attracted attention due to their unique binding property towards cis-diol-containing molecules. With the rapid development of recent research frontiers, such as environmental analysis, the food industry and bioanalysis, the demand for high-performance boronate affinity materials in sample preparation is continually growing. To overcome the various challenges of sample preparations, boronate affinity materials with certain properties should be employed. Due to efforts in the development of different synthetic pathways for boronate affinity materials, currently, boronate affinity materials are able to cope with the majority of tasks presented recent research. To understand this advancement in a more systematic way, we can evaluate the performance of boronate affinity materials from three major aspects: the binding capacity, working pH and selectivity. For a high binding capacity, boronate affinity materials with a porous structure are always the first choice. Furthermore, the molecular sieve effect of meso/micropores will significantly prevent the interference of macromolecules, which makes the boronate affinity porous material a promising candidate for sample preparation towards small molecule detection. For lowering the working pH, apart from the employment of advanced boronic acid ligands [157], multivalent binding is also an effective solution. To accomplish the multivalent binding, polymer brushes are the most commonly used substrate. In the meantime, this strategy is able to enhance both the binding capacity and binding strength, which allows for the selective enrichment of cisdiol-containing molecules from trace concentrations. To improve the selectivity, the employment of the molecular imprinting strategy is the most effective approach. Especially, the antibodylike specificity of the molecularly boronate affinity imprinted materials is extremely favorable for the sample preparation of complicated biofluid samples. For future developments, we expect the combination of boronate affinity materials with other functionalities in sample preparation, such as detection and determination, will be an active

Table 3 Application of boronate affinity materials in sample preparation procedures for biofluid samples. Sample

Analyte

Analytical techniques

LODs

Binding Capacity

Sample volume

Working pH

Reference

BA-MIP-MNPs poly(thiophene-3-boronic acid)-modified carbon fiber bundle CTAB coated IPBA@mPSF Fe3O4@ POSS-AAPBA PBA@POSS@SCF Fe3O4@FPBA MNPs Fe3O4@PEI-FPBA PAAPBA grafted PDA coated magGO ATTApoly(AEMA)eAu-MPBA Si@pNIPAm-b-pBA PEI-PBA-MNPs BA assisted glycan-imprinted MNPs APBA/GO hybrid monolithic column Fe3O4/PDA/GO/PEI/CBX boric acid-modified titania PEI-PBA-SNPs BA-RAMs APBA-PVA macroporous particles AAPBA-PGMA microspheres Wulff-type BA modified monolithic column

human serum rat plasma

glycoproteins (RNase B, TRF) catecholamines (adrenaline, noradrenaline, dopamine)

MALDI-TOF MS HPLC-UV

e 0.2 ng/mL

0.097 mmol/g e

200 mL 400 mL

7.4 11.0

[21] [50]

HepG2 cells human urine human urine rabbit plasma human urine human urine human plasma egg white human saliva human serum egg white human plasma egg white saliva calf serum human blood bovine serum human saliva

nucleosides (uridine, inosine, guanosine and adenosine) catecholamines (noradrenaline, epinephrine, isoprenaline) nucleosides (cytidine, uridine, guanosine, adenosine) cis-diol drugs (DBZ, CIE, CBE, IDHP) catecholamines (DA, EP, NE) catecholamines (Ado, SAL, DA, catechol) nucleosides (cytidine, uridine, inosine, guanosine, adenosine) glycoproteins (OVA, OVT) glycoproteins (HRP, TRF, RNase B, a-1-acid glycoprotein 2, etc) glycoproteins (HRP, AHSG) glycoproteins (OVA, OVT) glycoproteins glycoproteins (HRP, RNase B, OVA) glycoproteins (HRP, TRF, a-Amylase, etc) catecholamines (dopamine, norepinephrine, epinephrine) HbA1c nucleosides (uridine, guanosine) glycoproteins

HPLC-UV HPLC-UV HPLC-UV HPLC-UV LCeMS HPLC-FLD HPLC-UV SDS-PAGE MALDI-TOF MALDI-TOF SDS-PAGE MALDI-TOF MALDI-TOF MALDI-TOF HPLC-UV IE-HPLC HPLC-UV MALDI-TOF

1.1e1.7 ng/mL 0.8e1.3 ng/mL 5.1e6.1 ng/mL 6.3e21 ng/mL 0.03e0.2 ng/mL 0.32e4.5 ng/mL 6.24e14.07 ng/mL 40 mg/mL 0.05 ng/mL e 5 mg/mL 100 ng/mL 0.13 mM 0.4 pg/mL 5 ng/mL e 1 ng/mL 1 mg/mL

e 192.0 mmol/g 175e400 mg/g 80.6 mmol/g 3.45 mg/g 1111 mmol/g 30.83 mg/g 98.0 mg/g 0.35 mmol/g 0.12 mmol/g 5.12 mg/g 164.7 mg/g 53.0 mg/g 0.76 mmol/g e e 99.2 mmol/g e

10000 mL 10000 mL 500 mL 1000 mL 1000 mL 950 mL 2000 mL 1000 mL 300 mL 200 mL 100 mL 20 mL 300 mL 300 mL 500 mL 100 mL 500 mL 100 mL

10.3 8.0 9.0 8.5 8.5 9.0 9.0 7.4 7.0 7.4 8.5 7.4 9.0 7.4 9.0 8.4 9.0 7.0

[63] [68] [69] [81] [83] [97] [98] [102] [105] [204] [130] [131] [149] [152] [153] [154] [155] [156]

MS MS MS MS MS

MS

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

Material

PEI: polyethyleneimine; PBA: phenyl boronic acid, SNPs: silica nanoparticles, BA: boronate affinity; RAMs: restricted-access materials, PDA: polydopamine, CBX: carboxybenzoboroxole, APBA: aminophenylboronic acid; pNIPAm: poly- N-isopropylacrylamide, CTAB: hexadecyltrimethylammonium bromide, IPBA: (4-(1H-imidazole)phenyl) boronic acid, PSF: polysulfone, POSS: polyhedral oligomeric silsesquioxanes, AAPBA: 3acrylamidophenylboronic acid, SCF: sulfhydryl cotton, ATTA: attapulgite, AEMA: [2-(acryloyloxy) ethyl] trimethylammonium chloride, MPBA: 4-mercaptophenylboronic acid; PVA: polyvinylalcohol; PGMA: poly(glycidylmethacrylate); FPBA: formylphenylboronic acid.

13

14

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

research field. The “all-in-one” materials will be very beneficial for the simplification of sample preparation. Fortunately, a few works have recently been proposed to combine these multifunctionalities [54e56,123]. We do believe, with this work as a head start, that boronate affinity materials will certainly find increasing promising applications in sample preparation in the future. Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgement We acknowledge the financial support of the grants from the National Natural Science Foundation of China (21804003), Natural Science Foundation of Anhui Province (1908085QH349), the Open Project of the State Key Laboratory of Analytical Chemistry for Life Science (SKLACLS1709), the Key Project of the Natural Science Foundation of Bengbu Medical University (BYKY1702ZD, BYKY1665).

[20]

[21]

[22]

[23]

[24]

[25]

[26]

[27]

[28]

References [29] [1] X. Liu, W.H. Scouten, Boronate Affinity Chromatography. Affinity Chromatography, Springer, 2000. [2] H. Li, Z. Liu, Recent advances in monolithic column-based boronate-affinity chromatography, Trends Anal. Chem. 37 (2012) 148e161. [3] R. Nishiyabu, Y. Kubo, T.D. James, J.S. Fossey, Boronic acid building blocks: tools for sensing and separation, Chem. Commun. 47 (2011) 1106e1123. [4] J.B. Biot, Memoire sur plusieurs point fondamentaux de mecanique chimique, Mem. Acad. Sci. 16 (1838) 229e396. [5] F.K. Bell, C.J. Carr, W.E. Evans, J.C. Krantz Jr., Sugar alchols X: the effect of certain sugar alcohols and their anhydrides on the dissociation of boric acid, J. Phys. Chem. 42 (1938) 507e513. €eseken, The use of boric acid for the determination of the configuration [6] J. Bo of carbohydrates, Adv Carbohydr. Chem. (1949) 189e210. [7] A. Foster, Zone electrophoresis of carbohydrates, Adv Carbohydr. Chem. (1957) 81e115. [8] H.L. Weith, J.L. Wiebers, P.T. Gilham, Synthesis of cellulose derivatives containing the dihydroxyboryl group and a study of their capacity to form specific complexes with sugars and nucleic acid components, Biochem 9 (1970) 4396e4401. [9] A.M. Yurkevich, I.I. Kolodkina, E.A. Ivanova, E.I. Pichuzhkina, Study of the interaction of polyols with polymers containing n-substituted [(4boronophenyl) methyl]-ammonio groups, Carbohydr. Res. 43 (1975) 215e224. [10] V.K. Akparov, V.M. Stepanov, Phenylboronic acid as a ligand for biospecific chromatography of serine proteinases, J. Chromatogr. 155 (1978) 329e336. nsson, K. Mosbach, High-perfor[11] M. Glad, S. Ohlson, L. Hansson, M.-O. Ma mance liquid affinity chromatography of nucleosides, nucleotides and carbohydrates with boronic acid-substituted microparticulate silica, J. Chromatogr. 200 (1980) 254e260. [12] B.J. Johnson, Synthesis of a nitrobenzeneboronic acid-substituted polyacrylamide and its use in purifying isoaccepting transfer ribonucleic acids, Biochem 20 (1981) 6103e6108. [13] D. Li, Q. Li, S. Wang, J. Ye, H. Nie, Z. Liu, Pyridinylboronic acid-functionalized organicesilica hybrid monolithic capillary for the selective enrichment and separation of cis-diol-containing biomolecules at acidic pH, J. Chromatogr. A 1339 (2014) 103e109. [14] Q. Yang, D. Huang, P. Zhou, Synthesis of a SiO 2/TiO 2 hybrid boronate affinity monolithic column for specific capture of glycoproteins under neutral conditions, Analyst 139 (2014) 987e991. [15] Y. Li, X. Zhang, C. Deng, Functionalized magnetic nanoparticles for sample preparation in proteomics and peptidomics analysis, Chem. Soc. Rev. 42 (2013) 8517e8539. [16] B. Elmas, S. Senel, A. Tuncel, A new thermosensitive fluorescent probe for diol sensing: poly (N-isopropylacrylamide-co-vinylphenylboronic acid)alizarin red S complex, React. Funct. Polym. 67 (2007) 87e96. [17] G.C. de Lusançay, S. Norvez, I. Iliopoulos, Temperature-controlled release of catechol dye in thermosensitive phenylboronate-containing copolymers: a quantitative study, Eur. Polym. J. 46 (2010) 1367e1373. [18] Q. Jin, L.-P. Lv, G.-Y. Liu, J.-P. Xu, J. Ji, Phenylboronic acid as a sugar-and pHresponsive trigger to tune the multiple micellization of thermo-responsive block copolymer, Polymer 51 (2010) 3068e3074. [19] Z. Liu, K. Ullah, L. Su, F. Lv, Y. Deng, R. Dai, Y. Li, Y. Zhang, Switchable boronate

[30] [31] [32]

[33]

[34]

[35]

[36]

[37]

[38]

[39]

[40] [41]

[42]

[43]

[44]

[45] [46]

affinity materials for thermally modulated capture, separation and enrichment of cis-diol biomolecules, J. Mater. Chem. 22 (2012) 18753e18756. Z. Xu, K.M.A. Uddin, L. Ye, Boronic acid terminated thermo-responsive and fluorogenic polymer: controlling polymer architecture for chemical sensing and affinity separation, Macromolecules 45 (2012) 6464e6470. Z. Bie, Y. Chen, J. Ye, S. Wang, Z. Liu, Boronate-affinity glycan-oriented surface imprinting: a new strategy to mimic lectins for the recognition of an intact glycoprotein and its characteristic fragments, Angew. Chem. Int. Ed. 54 (2015) 10211e10215. S.W. Li, K.G. Yang, N. Deng, Y. Min, L.K. Liu, L.H. Zhang, Y.K. Zhang, Thermoresponsive epitope surface-imprinted nanoparticles for specific capture and release of target protein from human plasma, ACS Appl. Mater. Interfaces 8 (2016) 5747e5751. W. Zhang, W. Liu, P. Li, H. Xiao, H. Wang, B. Tang, A fluorescence nanosensor for glycoproteins with activity based on the molecularly imprinted spatial structure of the target and boronate affinity, Angew. Chem. Int. Ed. 53 (2014) 12489e12493. S. Kruss, A.J. Hilmer, J. Zhang, N.F. Reuel, B. Mu, M.S. Strano, Carbon nanotubes as optical biomedical sensors, Adv. Drug Deliv. Rev. 65 (2013) 1933e1950. D.-W. Hwang, S. Lee, M. Seo, T.D. Chung, Recent advances in electrochemical non-enzymatic glucose sensorseA review, Anal. Chim. Acta 1033 (2018) 1e34. D. Li, Y. Chen, Z. Liu, Boronate affinity materials for separation and molecular recognition: structure, properties and applications, Chem. Soc. Rev. 44 (2015) 8097e8123. Z. Liu, H. He, Synthesis and applications of boronate affinity materials: from class selectivity to biomimetic specificity, Acc. Chem. Res. 50 (2017) 2185e2193. T.A. Mattes, J.C. Escalante-Semerena, Facile isolation of alpha-ribazole from vitamin B-12 hydrolysates using boronate affinity chromatography, J. Chromatogr. B-Anal. Technol. Biomed. Life Sci. 1090 (2018) 52e55. S. Milkovska-Stamenova, R. Hoffmann, Identification and quantification of bovine protein lactosylation sites in different milk products, J. Proteomics 134 (2016) 112e126. S. Milkovska-Stamenova, R. Hoffmann, Hexose-derived glycation sites in processed bovine milk, J. Proteomics 134 (2016) 102e111. I. Percin, N. Idil, A. Denizli, RNA purification from Escherichia coli cells using boronated nanoparticles, Colloids Surf., B 162 (2018) 146e153. E. Kim, H. Kang, I. Choi, J. Song, H. Mok, W. Jung, W.S. Yeo, Efficient enrichment and analysis of vicinal-diol-containing flavonoid molecules using boronic-acid-functionalized particles and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, J. Agric. Food Chem. 66 (2018) 4741e4747. J. Chen, X. Li, M. Feng, K. Luo, J. Yang, B. Zhang, Novel boronate material affords efficient enrichment of glycopeptides by synergized hydrophilic and affinity interactions, Anal. Bioanal. Chem. 409 (2017) 519e528. M. Pei, X. Zhu, X. Huang, Mixed functional monomers-based monolithic adsorbent for the effective extraction of sulfonylurea herbicides in water and soil samples, J. Chromatogr. A 1531 (2018) 13e21. L.X. Li, Z.N. Xia, J. Pawliszyn, Selective extraction and enrichment of glycoproteins based on boronate affinity SPME and determination by CIEF-WCID, Anal. Chim. Acta 886 (2015) 83e90. S. Wang, H. Li, X. Guan, T. Cheng, H. Zhang, Silica - boronate affinity material for quick enrichment of intracellular nucleosides, Talanta 166 (2017) 148e153. H. Li, X. Zhang, L. Zhang, W. Cheng, F. Kong, D. Fan, L. Li, W. Wang, Silica stationary phase functionalized by 4-carboxy-benzoboroxole with enhanced boronate affinity nature for selective capture and separation of cis-diol compounds, Anal. Chim. Acta 985 (2017) 91e100. H. Li, X. Zhang, L. Zhang, X. Wang, F. Kong, D. Fan, L. Li, W. Wang, Preparation of a silica stationary phase co-functionalized with Wulff-type phenylboronate and C12 for mixed-mode liquid chromatography, Anal. Chim. Acta 962 (2017) 104e113. n, Y.Y.-M. Li, J.-L. Liao, J. Mohammad, K.i. Nakazato, G. Pettersson, S. Hjerte Continuous beds: high-resolving, cost-effective chromatographic matrices, Nature 356 (1992) 810e811. F. Svec, J.M. Frechet, New designs of macroporous polymers and supports: from separation to biocatalysis, Science 273 (1996) 205e211. N. Tsujioka, N. Hira, S. Aoki, N. Tanaka, K. Hosoya, A new preparation method for well-controlled 3D skeletal epoxy resin-based polymer monoliths, Macromolecules 38 (2005) 9901e9903. S. Jin, W. Zhang, Q. Yang, L. Dai, P. Zhou, An inorganic boronate affinity inneedle monolithic device for specific capture of cis-diol containing compounds, Talanta 178 (2018) 710e715. J. Pan, J. Liu, Y. Ma, X. Huang, X. Niu, T. Zhang, X. Chen, F. Qiu, Wulff-type boronic acids suspended hierarchical porous polymeric monolith for the specific capture of cis-diol-containing flavone under neutral condition, Chem. Eng. J. 317 (2017) 317e330. Y. Zhang, M. Mei, X. Huang, D. Yuan, Extraction of trace nitrophenols in environmental water samples using boronate affinity sorbent, Anal. Chim. Acta 899 (2015) 75e84. L. Zhang, C. Liu, Q. Zhang, Online 2D-LC-MS/MS platform for analysis of glycated proteome, Anal. Chem. 90 (2018) 1081e1086. Q. Dong, S. Chi, X. Deng, Y. Lan, C. Peng, L. Dong, X. Wang, Boronate affinity

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

[47]

[48]

[49]

[50]

[51]

[52]

[53]

[54]

[55]

[56]

[57]

[58] [59]

[60]

[61]

[62]

[63]

[64]

[65]

[66]

[67]

[68]

monolith via two-step atom transfer radical polymerization for specific capture of cis-diol-containing compounds, Eur. Polym. J. 100 (2018) 270e277. X. Li, M. Jia, Y. Zhao, Z. Liu, H.A. Aisa, Preparation of phenylboronate affinity rigid monolith with macromolecular porogen, J. Chromatogr. A 1438 (2016) 171e178. L. Ying, D. Wang, H. Yang, X. Deng, C. Peng, C. Zheng, B. Xu, L. Dong, X. Wang, L. Xu, Y. Zhang, X. Wang, Synthesis of boronate-decorated polyethyleneimine-grafted porous layer open tubular capillaries for enrichment of polyphenols in fruit juices, J. Chromatogr. A 1544 (2018) 23e32. J. He, Z. Liu, L. Ren, Y. Liu, P. Dou, K. Qian, H. Chen, On-line coupling of in-tube boronate affinity solid phase microextraction with high performance liquid chromatographyeelectrospray ionization tandem mass spectrometry for the determination of cis-diol biomolecules, Talanta 82 (2010) 270e276. X. Ling, Z. Chen, Boronate affinity solid-phase extraction of cis-diol compounds by a one-step electrochemically synthesized selective polymer sorbent, Anal. Bioanal. Chem. 410 (2018) 501e508. M. Espina-Benitez, J. Randon, C. Demesmay, V. Dugas, Development and application of a new in-line coupling of a miniaturized boronate affinity monolithic column with capillary zone electrophoresis for the selective enrichment and analysis of cis-diol-containing compounds, J. Chromatogr. A 1494 (2017) 65e76. H. Jiang, C. Qi, J. Chu, B. Yuan, Y. Feng, Profiling of cis-Diol-containing nucleosides and ribosylated metabolites by boronate-affinity organic-silica hybrid monolithic capillary liquid chromatography/mass spectrometry, Sci. Rep. 5 (2015) 7785. Z. Lin, J. Pang, H. Yang, Z. Cai, L. Zhang, G. Chen, One-pot synthesis of an organiceinorganic hybrid affinity monolithic column for specific capture of glycoproteins, Chem. Commun. 47 (2011) 9675e9677. X.T. Luo, B.D. Cai, L. Yu, J. Ding, Y.Q. Feng, Sensitive determination of brassinosteroids by solid phase boronate affinity labeling coupled with liquid chromatography-tandem mass spectrometry, J. Chromatogr. A 1546 (2018) 10e17. L. Yu, J. Ding, Y. Wang, P. Liu, Y. Feng, 4-Phenylaminomethyl-Benzeneboric acid modified tip extraction for determination of brassinosteroids in plant tissues by stable isotope labeling-liquid chromatography-mass spectrometry, Anal. Chem. 88 (2016) 1286e1293. J. Ding, L. Mao, N. Guo, L. Yu, Y. Feng, Determination of endogenous brassinosteroids using sequential magnetic solid phase extraction followed by in situ derivatization/desorption method coupled with liquid chromatographytandem mass spectrometry, J. Chromatogr. A 1446 (2016) 103e113. J.S. Beck, J. Vartuli, W.J. Roth, M. Leonowicz, C. Kresge, K. Schmitt, C. Chu, D.H. Olson, E. Sheppard, S. McCullen, A new family of mesoporous molecular sieves prepared with liquid crystal templates, J. Am. Chem. Soc. 114 (1992) 10834e10843. X. Feng, G. Fryxell, L. Wang, A.Y. Kim, J. Liu, K. Kemner, Functionalized monolayers on ordered mesoporous supports, Science 276 (1997) 923e926. D. Zhao, J. Feng, Q. Huo, N. Melosh, G.H. Fredrickson, B.F. Chmelka, G.D. Stucky, Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores, Science 279 (1998) 548e552. Y. Meng, D. Gu, F. Zhang, Y. Shi, H. Yang, Z. Li, C. Yu, B. Tu, D. Zhao, Ordered mesoporous polymers and homologous carbon frameworks: amphiphilic surfactant templating and direct transformation, Angew. Chem. Int. Ed. 44 (2005) 7053e7059. Y. Xu, Z. Wu, L. Zhang, H. Lu, P. Yang, P.A. Webley, D. Zhao, Highly specific enrichment of glycopeptides using boronic acid-functionalized mesoporous silica, Anal. Chem. 81 (2009) 503e508. M. Chen, R. Wang, Y. Zhu, M.Z. Liu, F. Zhu, J. Xiao, X. Chen, 4Mercaptophenylboronic acid-modified spirally-curved mesoporous silica nanofibers coupled with ultra performance liquid chromatography-mass spectrometry for determination of brassinosteroids in plants, Food Chem. 263 (2018) 51e58. T. Cheng, Y. Zhang, X. Liu, X. Zhang, H. Zhang, Surfactant assisted enrichment of nucleosides by using a sorbent consisting of magnetic polysulfone capsules and mesoporous silica nanoparticles modified with phenylboronic acid, Microchim. Acta 184 (2017) 271e278. T. Cheng, Y. Zhang, X. Liu, X. Zhang, H. Zhang, A filter paper coated with phenylboronic acid-modified mesoporous silica for enrichment of intracellular nucleosides prior to their quantitation by HPLC, Microchim. Acta 184 (2017) 4007e4013. J. Feng, X. She, X. He, J. Zhu, Y. Li, C. Deng, Synthesis of magnetic graphene/ mesoporous silica composites with boronic acid-functionalized pore-walls for selective and efficient residue analysis of aminoglycosides in milk, Food Chem. 239 (2018) 612e621. Y. Li, C. Deng, N. Sun, Hydrophilic probe in mesoporous pore for selective enrichment of endogenous glycopeptides in biological samples, Anal. Chim. Acta 1024 (2018) 84e92. B. Jiang, Q. Wu, N. Deng, Y. Chen, L. Zhang, Z. Liang, Y. Zhang, Hydrophilic GO/ Fe3O4/Au/PEG nanocomposites for highly selective enrichment of glycopeptides, Nanoscale 8 (2016) 4894e4897. H. He, Z. Zhou, C. Dong, X. Wang, Q. Yu, Y. Lei, L.Q. Luo, Y. Feng, Facile synthesis of a boronate affinity sorbent from mesoporous nanomagnetic polyhedral oligomeric silsesquioxanes composite and its application for enrichment of catecholamines in human urine, Anal. Chim. Acta 944 (2016) 1e13.

15

[69] L. Gao, Y. Wei, Fabrication of boronate-decorated polyhedral oligomeric silsesquioxanes grafted cotton fiber for selective enrichment of nucleosides in urine, J. Sep. Sci. 39 (2016) 2365e2373. [70] S.C. Liu, S. Shinde, J.M. Pan, Y. Ma, Y. Yan, G. Pan, Interface-induced growth of boronate-based metal-organic framework membrane on porous carbon substrate for aqueous phase molecular recognition, Chem. Eng. J. 324 (2017) 216e227. [71] X. Zhu, J. Gu, J. Zhu, Y. Li, L. Zhao, J. Shi, Metal-organic frameworks with boronic acid suspended and their implication for cis-diol moieties binding, Adv. Funct. Mater. 25 (2015) 3847e3854. [72] G. Chen, X. Fang, Q. Chen, J. Zhang, Z. Zhong, J. Xu, F. Zhu, G. Ouyang, Boronic acid decorated defective metal-organic framework nanoreactors for highefficiency carbohydrates separation and labeling, Adv. Funct. Mater. 27 (2017) 1702126. [73] E. Guihen, Nanoparticles in modern separation science, Trends Anal. Chem. 46 (2013) 1e14. pez-Serrano, R.M. Olivas, J.S. Landaluze, C. C [74] A. Lo amara, Nanoparticles: a global vision. Characterization, separation, and quantification methods. Potential environmental and health impact, Anal. Methods 6 (2014) 38e56. [75] W. Zhou, N. Yao, G. Yao, C. Deng, X. Zhang, P. Yang, Facile synthesis of aminophenylboronic acid-functionalized magnetic nanoparticles for selective separation of glycopeptides and glycoproteins, Chem. Commun. (2008) 5577e5579. [76] Z. Lin, J. Zheng, F. Lin, L. Zhang, Z. Cai, G. Chen, Synthesis of magnetic nanoparticles with immobilized aminophenylboronic acid for selective capture of glycoproteins, J. Mater. Chem. 21 (2011) 518e524. [77] L. Liang, Z. Liu, A self-assembled molecular team of boronic acids at the gold surface for specific capture of cis-diol biomolecules at neutral pH, Chem. Commun. 47 (2011) 2255e2257. [78] H. Fan, C. Wang, Y. Wei, Synthesis and application of boronic acidfunctionalized magnetic adsorbent for sensitive analysis of salbutamol residues in pig tissues, Biomed. Chromatogr. 29 (2015) 1834e1841. [79] S. Zhang, X. He, L. Chen, Y. Zhang, Boronic acid functionalized magnetic nanoparticles via thiol-ene click chemistry for selective enrichment of glycoproteins, New J. Chem. 38 (2014) 4212e4218. [80] L. Jiang, Y. Chen, Y. Luo, Y. Tan, M. Ma, B. Chen, Q. Xie, X. Luo, Determination of catecholamines in urine using aminophenylboronic acid functionalized magnetic nanoparticles extraction followed by high-performance liquid chromatography and electrochemical detection, J. Sep. Sci. 38 (2015) 460e467. [81] J. Du, M.F. He, X. Wang, H. Fan, Y. Wei, Facile preparation of boronic acidfunctionalized magnetic nanoparticles with a high capacity and their use in the enrichment of cis-diol-containing compounds from plasma, Biomed. Chromatogr. 29 (2015) 312e320. [82] P. Xin, B. Li, J. Yan, J. Chu, Pursuing extreme sensitivity for determination of endogenous brassinosteroids through direct fishing from plant matrices and eliminating most interferences with boronate affinity magnetic nanoparticles, Anal. Bioanal. Chem. 410 (2018) 1363e1374. [83] Q. Qin, H. Li, X. Shi, G. Xu, Facile synthesis of Fe3O4@polyethyleneimine modified with 4-formylphenylboronic acid for the highly selective extraction of major catecholamines from human urine, J. Sep. Sci. 38 (2015) 2857e2864. [84] C. Liu, Y. Liao, X. Huang, Preparation of a boronic acid functionalized magnetic adsorbent for sensitive analysis of fluoroquinolones in environmental water samples, Anal. Methods 8 (2016) 4744e4754. [85] L. Gu, Y. Wang, J. Han, L. Wang, X. Tang, C. Li, L. Ni, Phenylboronic acidfunctionalized core-shell magnetic composite nanoparticles as a novel protocol for selective enrichment of fructose from a fructose-glucose aqueous solution, New J. Chem. 41 (2017) 13399e13407. [86] X. Zhang, J. Wang, X. He, L. Chen, Y. Zhang, Tailor-made boronic acid functionalized magnetic nanoparticles with a tunable polymer shell-assisted for the selective enrichment of glycoproteins/glycopeptides, ACS Appl. Mater. Interfaces 7 (2015) 24576e24584. [87] Z. Lin, J. Zheng, Z. Xia, H. Yang, L. Zhang G. Chen, One-pot synthesis of phenylboronic acid-functionalized core-shell magnetic nanoparticles for selective enrichment of glycoproteins, RSC Adv. 2 (2012) 5062e5065. [88] L. Zhao, Y. Zhang, J. Wei, D. Cao, K. Liu, X. Qian, A rapid isolation and identification method for blocked N-terminal peptides by isothiocyanate-coupled magnetic nanoparticles and MS, Proteomics 9 (2009) 4416e4420. [89] Z. Lin, J. Zheng, F. Lin, L. Zhang, Z. Cai, G. Chen, Synthesis of magnetic nanoparticles with immobilized aminophenylboronic acid for selective capture of glycoproteins, J. Mater. Chem. 21 (2011) 518e524. [90] H. Zhu, H. Yao, K. Xia, J. Liu, X. Yin, W. Zhang, J. Pan, Magnetic nanoparticles combining teamed boronate affinity and surface imprinting for efficient selective recognition of glycoproteins under physiological pH, Chem. Eng. J. 346 (2018) 317e328. [91] S. Li, D. Li, L. Sun, Y. Yao, C. Yao, A designable aminophenylboronic acid functionalized magnetic Fe3O4/ZIF-8/APBA for specific recognition of glycoproteins and glycopeptides, RSC Adv. 8 (2018) 6887e6892. [92] C. Feng, X. Huang, Polymer brushes: efficient synthesis and applications, Acc. Chem. Res. 51 (2018) 2314e2323. [93] C. Li, J. Yuan, C. Wang, Y. Wei, Molecular bottlebrush polymer modified magnetic adsorbents with high physicochemical selectivity and unique shape selectivity, J. Chromatogr. A 1564 (2018) 16e24. [94] F. Zhou, W. Huck, Surface grafted polymer brushes as ideal building blocks

16

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

for “smart” surfaces, Phys. Chem. Chem. Phys. 8 (2006) 3815e3823. [95] S. Zhang, W. Guo, J. Wei, C. Li, X. Liang, M. Yin, Terrylenediimide-based intrinsic theranostic nanomedicines with high photothermal conversion efficiency for photoacoustic imaging-guided cancer therapy, ACS Nano 11 (2017) 3797e3805. [96] H. Ma, L.D. Jiang, S. Hajizadeh, H. Gong, B. Lu, L. Ye, Nanoparticle-supported polymer brushes for temperature-regulated glycoprotein separation: investigation of structure-function relationship, J. Mater. Chem. B 6 (2018) 3770e3781. [97] Y. Deng, Q. Gao, J. Ma, C. Wang, Y. Wei, Preparation of a boronate affinity material with ultrahigh binding capacity for cis-diols by grafting polymer brush from polydopamine-coated magnetized graphene oxide, Microchim. Acta 185 (2018) 189. [98] T. Cheng, S. Zhu, B. Zhu, X. Liu, H. Zhang, Highly selective capture of nucleosides with boronic acid functionalized polymer brushes prepared by atom transfer radical polymerization, J. Sep. Sci. 39 (2016) 1347e1356. [99] L. Jiang, H. Bagan, T. Kamra, T.C. Zhou, L. Ye, Nanohybrid polymer brushes on silica for bioseparation, J. Mater. Chem. B 4 (2016) 3247e3256. [100] Y. Shen, L. Dong, Y. Liang, Z. Liu, R. Dai, W. Meng, Y. Deng, Effect of the grafting ratio of poly(N-isopropylacrylamide) on thermally responsive polymer brush surfaces, J. Sep. Sci. 40 (2017) 524e531. [101] W. Wang, M. He, C. Wang, Y. Wei, Enhanced binding capacity of boronate affinity adsorbent via surface modification of silica by combination of atom transfer radical polymerization and chain-end functionalization for highefficiency enrichment of cis-diol molecules, Anal. Chim. Acta 886 (2015) 66e74. [102] L. Jiang, M.E. Messing, L. Ye, Temperature and pH dual-responsive core-brush nanocomposite for enrichment of glycoproteins, ACS Appl. Mater. Interfaces 9 (2017) 8985e8995. [103] H. Wang, Z. Bie, C. Lü, Z. Liu, Magnetic nanoparticles with dendrimer-assisted boronate avidity for the selective enrichment of trace glycoproteins, Chem. Sci. 4 (2013) 4298e4303. [104] K. Yoshida, K. Suwa, J. Anzai, Preparation of layer-by-layer films composed of polysaccharides and poly(amidoamine) dendrimer bearing phenylboronic acid and their pH- and sugar-dependent stability, Materials 9 (2016) 425. [105] D. Li, H. Xia, L. Wang, Branched polyethyleneimine-assisted boronic acidfunctionalized silica nanoparticles for the selective enrichment of trace glycoproteins, Talanta 184 (2018) 235e243. [106] D. Li, Z. Bie, Branched polyethyleneimine-assisted boronic acidfunctionalized magnetic nanoparticles for the selective enrichment of trace glycoproteins, Analyst 142 (2017) 4494e4502. [107] D. Li, Y. Li, X. Li, Z. Bie, X. Pan, Q. Zhang, Z. Liu, A high boronate avidity monolithic capillary for the selective enrichment of trace glycoproteins, J. Chromatogr. A 1384 (2015) 88e96. [108] Y. Xue, W. Shi, B. Zhu, X. Gu, Y. Wang, C. Yan, Polyethyleneimine-grafted boronate affinity materials for selective enrichment of cis-diol-containing compounds, Talanta 140 (2015) 1e9. [109] L. Gao, J. Du, C. Wang, Y. Wei, Fabrication of a dendrimer-modified boronate affinity material for online selective enrichment of cis-diol-containing compounds and its application in determination of nucleosides in urine, RSC Adv. 5 (2015) 106161e106170. [110] G. Wulff, A. Sarhan, Über die Anwendung von enzymanalog gebauten Polymeren zur Racemattrennung, Angew. Chem. 84 (1972), 364-364. [111] Y. Hoshino, H. Koide, T. Urakami, H. Kanazawa, T. Kodama, N. Oku, K.J. Shea, Recognition, neutralization, and clearance of target peptides in the bloodstream of living mice by molecularly imprinted polymer nanoparticles: a plastic antibody, J. Am. Chem. Soc. 132 (2010) 6644e6645. [112] A.G. Mayes, K. Mosbach, Molecularly imprinted polymer beads: suspension polymerization using a liquid perfluorocarbon as the dispersing phase, Anal. Chem. 68 (1996) 3769e3774. [113] J. Matsui, K. Fujiwara, T. Takeuchi, Atrazine-selective polymers prepared by molecular imprinting of trialkylmelamines as dummy template species of atrazine, Anal. Chem. 72 (2000) 1810e1813. [114] Z. An, Q. Shi, W. Tang, C.K. Tsung, C.J. Hawker, G.D. Stucky, Facile RAFT precipitation polymerization for the microwave-assisted synthesis of welldefined, double hydrophilic block copolymers and nanostructured hydrogels, J. Am. Chem. Soc. 129 (2007) 14493e14499. [115] N. Funaya, J. Haginaka, Matrine-and oxymatrine-imprinted monodisperse polymers prepared by precipitation polymerization and their applications for the selective extraction of matrine-type alkaloids from Sophora flavescens Aiton, J. Chromatogr. A 1248 (2012) 18e23. [116] A. Bossi, S.A. Piletsky, E.V. Piletska, P.G. Righetti, A.P. Turner, Surface-grafted molecularly imprinted polymers for protein recognition, Anal. Chem. 73 (2001) 5281e5286. [117] H. Yang, S. Zhang, F. Tan, Z. Zhuang, X. Wang, Surface molecularly imprinted nanowires for biorecognition, J. Am. Chem. Soc. 127 (2005) 1378e1379. [118] R. Xing, S. Wang, Z. Bie, H. He, Z. Liu, Preparation of molecularly imprinted polymers specific to glycoproteins, glycans and monosaccharides via boronate affinity controllableeoriented surface imprinting, Nat. Protoc. 12 (2017) 964e987. [119] J. Xie, G. Zhong, C. Cai, C. Chen, X. Chen, Rapid and efficient separation of glycoprotein using pH double-responsive imprinted magnetic microsphere, Talanta 169 (2017) 98e103. [120] S. Wang, J. Ye, Z. Bie, Z. Liu, Affinity-tunable specific recognition of glycoproteins via boronate affinity-based controllable oriented surface

imprinting, Chem. Sci. 5 (2014) 1135e1140. [121] M. Peng, H. Xiang, X. Hu, S. Shi, X. Chen, Boronate affinity-based surface molecularly imprinted polymers using glucose as fragment template for excellent recognition of glucosides, J. Chromatogr. A 1474 (2016) 8e13. [122] Y. Hao, R. Gao, D. Liu, G. He, Y. Tang, Z. Guo, A facile and general approach for preparation of glycoprotein-imprinted magnetic nanoparticles with synergistic selectivity, Talanta 153 (2016) 211e220. [123] P. Muhammad, J. Liu, R. Xing, Y. Wen, Y. Wang, Z. Liu, Fast probing of glucose and fructose in plant tissues via plasmonic affinity sandwich assay with molecularly-imprinted extraction microprobes, Anal. Chim. Acta 995 (2017) 34e42. [124] Z. Bie, R. Xing, X. He, Y. Ma, Y. Chen, Z. Liu, Precision imprinting of glycopeptides for facile preparation of glycan-specific artificial antibodies, Anal. Chem. 90 (2018) 9845e9852. [125] Y. Hu, W. Huang, Y. Tong, Q. Xia, M. Tian, Boronate-affinity hollow molecularly imprinted polymers for the selective extraction of nucleosides, New J. Chem. 41 (2017) 7133e7141. [126] X. Pan, X. He, Z. Liu, Molecularly imprinted mesoporous silica nanoparticles for specific extraction and efficient identification of Amadori compounds, Anal. Chim. Acta 1019 (2018) 65e73. [127] M. Khan, M.N. Tahir, S.F. Adil, H.U. Khan, M.R.H. Siddiqui, A.A. Al-warthan, W. Tremel, Graphene based metal and metal oxide nanocomposites: synthesis, properties and their applications, J. Mater. Chem. A 3 (2015) 18753e18808. [128] K. He, Z. Zeng, A. Chen, G. Zeng, R. Xiao, P. Xu, Z. Huang, J. Shi, L. Hu, G. Chen, Advancement of Ag-graphene based nanocomposites: an overview of synthesis and its applications, Small 14 (2018) 1800871. [129] R. Wang, Z. Chen, Boronate affinity monolithic column incorporated with graphene oxide for the in-tube solid-phase microextraction of glycoproteins, J. Sep. Sci. 41 (2018) 2767e2773. [130] C. Zhou, X. Chen, Z. Du, G. Li, X. Xiao, Z. Cai, A hybrid monolithic column based on boronate-functionalized graphene oxide nanosheets for online specific enrichment of glycoproteins, J. Chromatogr. A 1498 (2017) 90e98. [131] Q. Wu, B. Jiang, Y. Weng, J. Liu, S. Li, Y. Hu, K. Yang, Z. Liang, L. Zhang, Y. Zhang, 3-Carboxybenzoboroxole functionalized polyethylenimine modified magnetic graphene oxide nanocomposites for human plasma glycoproteins enrichment under physiological conditions, Anal. Chem. 90 (2018) 2671e2677. [132] J. Yang, X. He, L. Chen, Y. Zhang, Thiol-yne click synthesis of boronic acid functionalized silica nanoparticle-graphene oxide composites for highly selective enrichment of glycoproteins, J. Chromatogr. A 1513 (2017) 118e125. [133] B. Jiang, Y. Qu, L. Zhang, Z. Liang, Y. Zhang, 4-Mercaptophenylboronic acid functionalized graphene oxide composites: preparation, characterization and selective enrichment of glycopeptides, Anal. Chim. Acta 912 (2016) 41e48. [134] J. Luo, J. Huang, J. Cong, W. Wei, X. Liu, Double recognition and selective extraction of glycoprotein based on the molecular imprinted graphene oxide and boronate affinity, ACS Appl. Mater. Interfaces 9 (2017) 7735e7744. [135] J. Huang, Y. Wu, J. Cong, J. Luo, X. Liu, Selective and sensitive glycoprotein detection via a biomimetic electrochemical sensor based on surface molecular imprinting and boronate-modified reduced graphene oxide, Sensor. Actuator. B Chem. 259 (2018) 1e9. [136] X. An, X. He, L. Chen, Y. Zhang, Graphene oxide-based boronate polymer brushes via surface initiated atom transfer radical polymerization for the selective enrichment of glycoproteins, J. Mater. Chem. B 4 (2016) 6125e6133. [137] J. Su, X. He, L. Chen, Y. Zhang, A combination of "thiol - ene" click chemistry and surface initiated atom transfer radical polymerization: fabrication of boronic acid functionalized magnetic graphene oxide composite for enrichment of glycoproteins, Talanta 180 (2018) 54e60. [138] J. Liu, K. Yang, W. Shao, Y. Qu, S. Li, Q. Wu, L. Zhang, Y. Zhang, Boronic acidfunctionalized particles with flexible three-dimensional polymer branch for highly specific recognition of glycoproteins, ACS Appl. Mater. Interfaces 8 (2016) 9552e9556. [139] H. Hu, Y. Zhang, Y. Zhang, X. Huang, D. Yuan, Preparation of a new sorbent based on boronate affinity monolith and evaluation of its extraction performance for nitrogen-containing pollutants, J. Chromatogr. A 1342 (2014) 8e15. [140] X. Huang, X. Zhu, M. Pei, Solid-phase microextraction of sulfonylurea herbicides by using borate-reinforced multiple monolithic fibers, Microchim. Acta 185 (2018) 226. [141] C.O. Miles, J. Kilcoyne, P. McCarron, S.D. Giddings, T. Waaler, T. Rundberget, I.A. Samdal, K.E. Lovberg, Selective extraction and purification of azaspiracids from blue mussels (Mytilus edulis) using boric acid gel, J. Agric. Food Chem. 66 (2018) 2962e2969. [142] X. Pan, Y. Chen, P. Zhao, D. Li, Z. Liu, Highly efficient solid-phase labeling of saccharides within boronic acid functionalized mesoporous silica nanoparticles, Angew. Chem. Int. Ed. 54 (2015) 6173e6176. [143] M. Pan, Y. Sun, J. Zheng, W. Yang, Boronic acid-functionalized core-shellshell magnetic composite microspheres for the selective enrichment of glycoprotein, ACS Appl. Mater. Interfaces 5 (2013) 8351e8358. [144] S. Zhang, X. He, L. Chen, Y. Zhang, Boronic acid functionalized magnetic nanoparticles via thiol-ene click chemistry for selective enrichment of glycoproteins, New J. Chem. 38 (2014) 4212e4218. [145] X. Zhao, W. Wang, J. Wang, J. Yang, G. Xu, Urinary profiling investigation of

Y. Chen et al. / Analytica Chimica Acta 1076 (2019) 1e17

[146]

[147]

[148]

[149] [150]

[151]

[152]

[153]

[154]

[155]

[156]

[157]

metabolites with cis-diol structure from cancer patients based on UPLC-MS and HPLC-MS as well as multivariate statistical analysis, J. Sep. Sci. 29 (2006) 2444e2451. Q. Li, C. Lü, H. Li, Y. Liu, H. Wang, X. Wang, Z. Liu, Preparation of organic-silica hybrid boronate affinity monolithic column for the specific capture and separation of cis-diol containing compounds, J. Chromatogr. A 1256 (2012) 114e120. J. He, Z. Liu, L. Ren, Y. Liu, P. Dou, K. Qian, H. Chen, On-line coupling of in-tube boronate affinity solid phase microextraction with high performance liquid chromatographyeelectrospray ionization tandem mass spectrometry for the determination of cis-diol biomolecules, Talanta 82 (2010) 270e276. Z. Lin, L. Sun, W. Liu, Z. Xia, H. Yang, G. Chen, Synthesis of boronic acidfunctionalized molecularly imprinted silica nanoparticles for glycoprotein recognition and enrichment, J. Mater. Chem. B 2 (2014) 637e643. S. Jin, L. Liu, P. Zhou, Amorphous titania modified with boric acid for selective capture of glycoproteins, Microchim. Acta 185 (2018) 308. D. Li, T. Tu, M. Yang, C. Xu, Efficient preparation of surface imprinted magnetic nanoparticles using poly (2-anilinoethanol) as imprinting coating for the selective recognition of glycoprotein, Talanta 184 (2018) 316e324. D. Li, T. Tu, X. Wu, Efficient preparation of template immobilization-based boronate affinity surface-imprinted silica nanoparticles using poly (4aminobenzyl alcohol) as an imprinting coating for glycoprotein recognition, Anal. Methods 10 (2018) 4419e4429. D. Li, T. Tu, M. Yang, C. Xu, Efficient preparation of surface imprinted magnetic nanoparticles using poly (2-anilinoethanol) as imprinting coating for the selective recognition of glycoprotein, Talanta 184 (2018) 316e324. H. Xu, C. Wang, Y. Wei, A boronate affinity restricted-access material with external hydrophilic bottlebrush polymers for pretreatment of cis-diols in biological matrices, Chin. Chem. Lett. 29 (2018) 521e523. V.E. Tikhonov, M.I. Blagodatskikh, V.A. Postnikov, Z.S. Klemenkova, O.V. Vyshivannaya, A.R. Khokhlov, New approach to the synthesis of a functional macroporous poly(vinyl alcohol) network and design of boronate affinity sorbent for protein separation, Eur. Polym. J. 75 (2016) 1e12. C. Wang, H. Xu, Y. Wei, The preparation of high-capacity boronate affinity adsorbents by surface initiated reversible addition fragmentation chain transfer polymerization for the enrichment of ribonucleosides in serum, Anal. Chim. Acta 902 (2016) 115e122. Z. Bie, Y. Chen, H. Li, R. Wu, Z. Liu, Off-line hyphenation of boronate affinity monolith-based extraction with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for efficient analysis of glycoproteins/glycopeptides, Anal. Chim. Acta 834 (2014) 1e8. C. Lv, H. Li, H. Wang, Z. Liu, Probing the interactions between boronic acids and cis-diol containing biomolecules by affinity capillary electrophoresis, Anal. Chem. 85 (2013) 2361e2369.

Yang Chen received his bachelor's degree from Anhui Normal University in 2011 and Ph. D.degree from Nanjing University in 2017. After that, he joined Bengbu Medical University as a lecture. His research interests include

17 advanced affinity materials and their applications in molecular recognition, bioseparation and pharmaceutical analysis. He has published more than 10 peer-reviewed journal papers.

Ailan Huang obtained her master degree from Anhui Science and Technology University in 2016. After two years of working experience in FDA of Chuzhou. She became a teacher in Bengbu Medical University. Her research interest mainly focus on food chemistry and food analysis.

Yanan Zhang is an undergraduate from School of Pharmacy, Bengbu Medical University since 2017. She is carrying out the National Innovation Plan for College Students under the supervision of Dr. Yang Chen and Dr. Zijun Bie. Her major interest is the boronate affinity porous material.

Zijun Bie obtained her Ph.D from Nanjing University, China, in 2016. She was appointed as a lecturer at Bengbu Medical University in 2016. Her current major research interest is to develop boronate affinity materials and innovative approaches for sample separation and mass spectrometry analysis. She has already published 16 peer reviewed papers.