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Enhanced peroxidase-like activity of porphyrin functionalized ceria nanorods for sensitive and selective colorimetric detection of glucose
Materials Science and Engineering C 59 (2016) 445–453
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Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec
Enhanced peroxidase-like activity of porphyrin functionalized ceria nanorods for sensitive and selective colorimetric detection of glucose Qingyun Liu ⁎, Yanyuan Ding, Yanting Yang, Leyou Zhang, Lifang Sun, Pengpeng Chen, Chun Gao School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510, PR China
a r t i c l e
i n f o
Article history: Received 6 April 2015 Received in revised form 18 September 2015 Accepted 15 October 2015 Available online 17 October 2015 Keywords: Porphyrin CeO2 nanorods Colorimetric Nanocomposites Peroxidase
a b s t r a c t Ceria nanorods modified with 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H2TCPP) were prepared. These nanocomposites (H2TCPP–CeO2) exhibited the intrinsic peroxidase-like activity and could catalyze the oxidation of classical peroxidase substrate 3,3′,5,5′-tetramethylbiphenyl dihydrochloride (TMB·2HCl) in the presence of H2O2 to produce a typical color reaction from colorless to blue. Our results demonstrated that both the H2TCPP–CeO2 nanocomposites and CeO2 nanorods exhibited higher thermal durance than that of HRP. The affinity of The H2TCPP–CeO2 nanocomposites toward H2O2 and TMB is similar to that of HRP. Fluorescent results indicated that the catalytic mechanism of the H2TCPP–CeO2 nanocomposites were from the decomposition of H2O2 into hydroxyl radicals. Based on these studies, a simple, sensitive, and selective visual and colorimetric method using TMB as the substrate was designed to detect glucose when combined with glucose oxidase. The proposed colorimetric method can detect H2O2 at a low detection limit of 6.1 × 10−6 M and a dynamic range of 10−5–10−4 mol·L−1. This method can also detect glucose at a low detection limit of 3.3 × 10−5 mol·L−1 and a dynamic range of 5.0 × 10−5–1.0 × 10−4 mol·L−1. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Enzymes are efficient biological catalysts, which are involved in almost all reactions. Natural enzymes with high substrate specificity and high catalytic efficiency play central roles in a wide range of applications, such as clinical diagnosis, biotechnology, chemistry, and environmental science, and have been extensively studied for more than 200 years [1–4]. Unfortunately, the intrinsic drawbacks of their easy denaturation [5] and high costs in preparation and purification [6] limit their large scale applications. To overcome the limitations of natural enzymes, intense interest has grown in the development of nonenzymatic glucose sensors [7a] and artificial enzyme mimetics [7b]. Nanomaterials are attractive and are widely put to use because of their unique optical, electronic, magnetic, and catalytic properties [8]. In 2007, the excitingly intrinsic peroxidase-like activity of ferromagnetic nanoparticles, an inert nanomaterial, was reported [9] and aroused people's attention for the innovative research of nanomaterials in the enzyme mimetic field [10]. Various nanoparticles have been evaluated as enzymatic mimetics [11–39], including ferromagnetic NPs with peroxidase-like activity [11–20], ceria oxide NPs [21–24] and V2O5 nanowires [25] with oxidase mimetic properties, metal nanoparticles with oxidase or peroxidase-like activity [26–31], SiO2/PEG hybrid materials [22] and carbon-based nanomaterials. [23–39].
⁎ Corresponding author. E-mail addresses: [email protected], [email protected] (Q. Liu).
http://dx.doi.org/10.1016/j.msec.2015.10.046 0928-4931/© 2015 Elsevier B.V. All rights reserved.
Nanoceria, as an important rare-earth oxide nanostructure material, has attracted enormous interest in recent years, due to the unique physical and chemical properties compared with that of its bulk materials. Therefore, it has been widely applied in various areas, including catalysis, electrochemistry, photochemistry, metal polishing agent, fuel cells, gas sensors and luminescence [40–46]. In recent studies, cerium oxide nanoparticles (nanoceria) are found to be the potent free-radical scavengers as well as exhibit neuroprotective, radioprotective, and anti-inflammatory properties [47–49]. Nanoceria also have the unique property of being regenerative or autocatalytic [50]. In addition, the novel properties of nanomaterials are associated with their size, shape and morphology, such as sphere, rod, polyhedral, and cubic. [51–53]. Nanoceria with the higher level of Ce4+ oxidation state exhibited significant catalase-mimetic activity, while those with the higher level of Ce3+ oxidation state did not, so the decomposition of H2O2 to oxygen by nanoceria depended on the ratio of Ce3+/Ce4+, which could be modulated by morphology, H2O2 and phosphate solutions (e.g., phosphate buffered saline) [54] to improve catalase-mimetic activity. A new horseradish peroxidase (HRP) third-generation electrochemical biosensor based on ceria nanocubes has been established [55]. CeO2 nanoparticles can be used to detect glucose in human blood serum samples by colorimetric method [56]. However, the ceria nanostructures that have been investigated so far for their peroxidase mimetic activity have had zero dimensional shape. Porphyrin, tetrapyrrole derivatives as the representatives of functional molecular materials with large conjugated electronic molecular
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structures, have attracted great research interest in vastly diverse areas ranging from chemistry, physics, biology, and medicine to molecular device [57]. Porphyrins widely exist in organism and the energy transfer of the relevant important organelles. If we can obtain the functional porphyrin-ceria nanocomposites, it will provide excellent opportunities for applications in the fields of artificial enzyme mimetics, biosensor, electrocatalysis, luminescence, electronics, etc. However, to the best of our knowledge, one dimensional ceria nanorods as well as 5,10,15,20tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) modified ceria nanorods have not been reported thus far. In this paper, H2TCPP modified CeO2 nanorods were prepared by a facile two-step method. Interestingly, the as-prepared CeO2 nanorods and H2TCPP–CeO2 nanocomposites demonstrated peroxidase-like activity that they could catalyze oxidation of the substrate 3,3′,5,5′ertramethylbenzidine dihydrochloride (TMB·2HCl) in the presence of H2O2. Furthermore, the catalytic activity of H2TCPP–CeO2 nanocomposite showed much higher than that of pure CeO2 nanorods. As a result, H2TCPP–CeO2 nanocomposites were used as mimic enzyme by a colorimetric method for H2O2 detection. And we all know that the oxidation of glucose could be catalyzed by glucose oxidase (GOx) in the presence of oxygen to produce gluconic acid and H2O2. Therefore, a simple, sensitive and cheap colorimetric method has been developed for glucose detection (Scheme 1). The results indicate that this method is higher sensitive and selective for the detection of glucose and can be successfully used in the quantitative detection of glucose in buffer solution and even in human serum system. 2. Experimental section 2.1. Chemicals and reagents Cerium nitrate hexahydrate (Ce(NO3)3·6H2O), hydrogen peroxide (30 wt.%,H2O2), acetic acid (HAc), sodium acetate(NaAc), TMB·2HCl, glucose, fructose, lactose, and mannitol were purchased from Guangcheng Reagent Co. (Tianjin, China). Glucose oxidase (GOx, ≥200 U mg−1) was purchased from Sigma-Aldrich and stored in a refrigerator at −18 °C. All the regents were of analytical reagent grade and used without further purification. 5,10,15,20-Tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) was synthesized according to the previous literature [58]. 2.2. Preparation of CeO2 nanorods and porphyrin functionalized CeO2 nanocomposites (H2TCPP–CeO2) CeO2 nanorods were prepared according to a previous report [59]. In a typical procedure, Ce(NO3)3 (8 ml, 0.05 M) was added rapidly to H2O2 (8 ml, 30.0%) solution and stirred for ca. 10 min. The suspension was transferred into a 25 ml Teflon-lined autoclave, which was heated at 250 °C for 3 h. The system was then allowed to cool to room temperature naturally. The final product was washed with deionized water,
and dried at 60 °C for 12 h. Then CeO2 nanorods were obtained. Subsequently, the CeO2 nanorods was dissolved into 5 mM H2TCPP solution (pH = 8) was treated to an ultrasonic water bath for 1.5 h. The sample (H2TCPP–CeO2) was washed with NaOH solution (pH = 8) and dried at room temperature in air. The target product was successfully obtained and studied in the subsequent experiment.
2.3. Characterization The morphology and size distribution of the nanorods were imaged by transmission electron microscope (TEM JEM-2100, JEOL, Japan). The crystal structures of the products were determined by powder X-ray diffraction (XRD) patterns with graphite monochromatized Cu Kα radiation (D/Max2500PC, Rigaku, Japan). Fourier transform infrared (FTIR) spectra were taken in KBr pressed pellets on a NICOLET 380 FTIR spectrometer (Nicolet Thermo, USA). UV–vis absorption spectra were recorded on a MAPADA UV-3200PC spectrophotometer (Shanghai, China). X-ray photoelectron spectra (XPS) were recorded on a PHI Quantera SXM spectrometer with an Al Kα = 280.00 eV excitation source, and binding energies were calibrated by referencing the C1s peak (284.5 eV) to reduce the sample charge effect.
2.4. Mechanism of peroxidase-like activity of H2TCPP–CeO2 nanorods We presume that the nature of peroxidase-like activities of the H2TCPP–CeO2 nanorods may originate from their catalytic ability to H2O2 decomposition into •OH radicals. So we used a method of fluorescence to measure the •OH radicals with terephthalic acid as probe. The typical experimental procedure is as follows: H2O2 (10 mM), terephthalic acid (0.5 mM) and the CeO2 nanorods with different concentrations (0, 50, 100, 150, 200, 250, 300 μg/ml) were first incubated in acetate buffer (pH 3.8, 100 mM) at 40 °C for 40 min. After centrifugation, the solutions were used for fluorometric measurement by a Cary Eclipse spectrofluorophotometer (Varian, Inc., USA).
2.5. Kinetic analysis The reaction kinetic measurements were carried out in time course mode by monitoring the absorbance variation at 652 nm with a 1 s interval on a MAPADA UV-3200PC spectrophotometer. The experiments were carried out with 0.04 mg·mL−1 H2TCPP–CeO2 solution or 0.04 mg·mL− 1 CeO2 in reaction buffer (0.026 M NaAc, pH 3.8) with TMB·2HCl as substrate; H2O2 concentration was 25 mM for CeO2 and H2TCPP–CeO2 nanorods. The Michaelis–Menten constant was calculated according to the Michaelis–Menten eqn (1): v = Vmax [S] / (Km + [S]), where v is the initial velocity, [S] is the concentration of substrate, Km is the Michaelis constant and Vmax is the maximal reaction velocity.
2.6. H2O2 and glucose detection
Scheme 1. Schematic illustration of oxidation of glucose by GOx.
In a typical process, the solution of hydrogen peroxide with a given concentration was added to TMB (final concentration of 0.25 mM) solution in the presence of H2TCPP–CeO2 nanocomposites solution (final concentration of 0.02 mg·mL−1) and the NaAc buffer (pH 3.8). The mixture was incubated at room temperature for 10 min. Glucose detection was realized as follows: a) 100 μl of 0.5 mg·mL− 1 GOx and 500 μL of glucose of different concentrations in PBS (pH 7.0) were incubated at 37 °C for 0.5 h; b) 200 μL of 0.5 mM TMB, 30 μL of the H2TCPP–CeO2 nanocomposites solution, and 1.17 mL of buffer (pH 3.8) were added into the above 200 μL glucose reaction solution. The mixed solution was used to perform the time course measurement.
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Fig. 1. Powder X-ray diffraction pattern of the as-prepared samples (A, CeO2 nanorods; B, H2TCPP–CeO2 nanocomposites).
3. Results and discussion 3.1. Characterization of as-synthesized CeO2 nanorods and H2TCPP–CeO2 nanocomposites Fig. 1 shows the XRD pattern of the obtained CeO2 nanorods (Fig. 1A) and that of H2TCPP–CeO2 nanocomposites (Fig. 1B). The diffraction peaks observed show a good match with CeO2 (JCPDS 34-0394), indicating that the prepared CeO2 nanorods have a cubic, fluorite-type structure and high purity. However, expect for the corresponding diffraction peak of CeO2 crystal, a weak diffraction peak located 22.0° (d = 0.404 nm) was observed in the XRD pattern of H2TCPP–CeO2 nanorods, due to the H2TCPP aggregates on the surface of CeO2 nanorods through coordination, adsorption and π–π supramolecular interactions [60–61]. The morphology and size of the obtained CeO2 nanorods (occasionally found less CeO2 nanoparticles) and H2TCPP–CeO2 nanocomposites were imaged by Transmission electron microscopy (TEM), shown in Fig. 2. TEM images showed freshly synthesized CeO2 nanorods with a variable size from 24 nm up to several hundred nm in length and average 21 nm in width. The morphologies of H2TCPP–CeO2 nanocomposites were also similar to those of CeO2 nanorods, suggesting that a few H2TCPP molecules were attached on the surface of CeO2 nanorods through coordination between H2TCPP molecules and CeO2 together with π–π superamolecular interactions existed in interporphyrin
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Fig. 3. FTIR spectra of the as-prepared H2TCPP–CeO2 nanocomposites (A) and H2TCPP (B).
molecules, which further confirmed by the spectra of FI-IR and UV–vis in the subsequent experiments. The H2TCPP functionalized CeO2 was further confirmed by FI-IR and UV–vis absorption spectra, respectively. The infrared spectra of H2TCPP–CeO2 nanocomposites and H2TCPP are shown in Fig. 3A and B, respectively. The infrared spectrum of H2TCPP–CeO2 nanocomposites is different from that of the pure H2TCPP. The spectrum showed that 1697 cm−1 attributed to the vibration peak of carbonyl group attached on macrocycles of porphyrin disappeared, compared with that of H2TCPP, which verified the coordination interaction existed between carbonyl groups from H2TCPP molecules and CeO2 nanorods. Moreover, the stretching vibration at ca. 1640 cm−1 and 1540 cm−1 assigned as the C _C bonds and C_N double bond that become broader. Fig. 3 shows a broad and intense peak characteristic of O–H groups centered at 3426 cm−1 (H2TCPP) and 3400 cm−1 (H2TCPP–CeO2). Thus, the FTIR data verified that the coordination interaction existed between H2TCPP molecules and CeO2 nanorods. Fig. 4 shows the UV–vis electronic absorption spectra of dilute DMF solution of H2TCPP (A), H2TCPP–CeO2 nanocomposites (B) and CeO2 nanorods (C) dispersed in ultrapure water, respectively. From the figure, it can be seen that H porphyrin–porphyrin stacking modes of H2TCPP–CeO2 nanocomposites (B) can be easily achieved by electronic absorption spectroscopic examination, because the absorption peak of H2TCPP–CeO2 nanocomposites at 413 nm with 6 nm blue-shift, compared with that of the dilute DMF solution of H2TCPP monomolecule at 419 nm (A). This result revealed intensive inter-molecular interaction
Fig. 2. TEM images of the CeO2 nanorods (A) and the H2TCPP–CeO2 nanorods (B).
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Fig. 6. A comparison of the catalytic activities of different materials in the peroxidase-like oxidation of TMB in NaAc buffer solution (pH 3.8) after 15 min. (Sample specifications: A: H2O2 + commercial CeO2 + TMB, B: H2O2 + CeO2 nanrods + TMB, C: H2O2 + H2TCPP– CeO2 nanocomposites + TMB, D: H2TCPP–CeO2 nanocomposites + TMB, E: H2O2 + TMB, F. H2TCPP–CeO2 nanocomposites, G. TMB).
Fig. 4. The UV–vis absorption spectra of the dilute DMF solution of H2TCPP (A), H2TCPP– CeO2 nanocomposites dispersed in pure water (B) and CeO2 nanorods (C), respectively.
of porphyrin molecules together with coordination interaction between H2TCPP and CeO2 in the nanocomposites [62–63]. It can also be seen that the similarity in the electronic absorption spectra both the nanorods dispersed in pure water and the dilute DMF solution of H2TCPP gives an unambiguous evidence for one of the composition of the nanocomposites from the porphyrin molecules. The Ce 3d electron core level XPS spectrum for as-prepared CeO2 nanorods is shown in Fig. 5. The XPS spectrum from cerium is complex and splits into Ce 3d3/2 and Ce 3d5/2 with multiple shake-up and shakedown satellites. The peaks between 895 and 910 eV correspond to the Ce 3d3/2 while peaks between 875 and 895 eV belong to the Ce 3d5/2 levels [64]. Greater intensity peaks corresponding to Ce4 + were observed in sample, revealing a higher Ce4+/Ce3+ ratio. XPS analysis indicates that a slight reduced surface of the CeO2 nanorods could be obtained according a simple hydrothermal method.
3.2. Peroxidase-like activity of H2TCPP–CeO2 nanocomposites
photographs of different reaction systems. It can be observed that additional control experiments using TMB in the absence of H2TCPP–CeO2 composite or H2O2 show no obvious color change, indicating that the two components are required for the reaction (Fig. 6). It can also be seen that the catalytic activity of CeO2 nanorods modified with H2TCPP was much higher than that of commercial CeO2 and CeO2 nanorods alone, revealing that an activated sample of H2TCPP–CeO2 exhibited enhanced peroxidase-like catalytic activity under identical conditions. The time-dependent UV–vis spectra of different reaction systems at room temperature were shown in Fig. 7. The absorbance of the H2TCPP– CeO2 nanocomposite–TMB–H2O2 system at 652 nm was much higher than that of H2O2–CeO2 nanorod–TMB, H2O2–commercial CeO2–TMB and H2O2–TMB system. Other than the different morphologies of CeO2 nanostructures reported [56], most important of all, it is due to the introduction of H2TCPP molecules on the surface of CeO2 nanorods. 3.3. Optimization of the experimental conditions The catalytic relative activity of H2TCPP–CeO2 nanocomposites is dependent on pH, temperature and the concentration of H2O2, which is very similar to that of HRP and the reported CeO2 NPs [56]. The peroxidase-like activities of H2TCPP–CeO2 nanocomposites toward the oxidation of TMB by H2O2 was investigated while varying the pH from
To investigate the peroxidase-like activity of H2TCPP–CeO2 nanocomposites, the catalysis of peroxidase substrate TMB was tested in the presence of H2O2. The oxidation of TMB has a characteristic absorbance at 652 nm and corresponding blue color [65]. Fig. 6 shows
Fig. 5. Raw XPS spectrum of as-prepared CeO2 nanorods.
Fig. 7. Time-dependent absorbance changes at 652 nm of TMB in different systems. In this experiment, H2TCPP–CeO2 nanocomposite concentration: 40 μg/ml, TMB concentration: 0.05 mM, H2O2 concentration: 25 mM, the concentration of acetate buffer solution (pH = 3.8): 0.12 M.: (A) H2O2 + H2TCPP–CeO2 nanocomposites + TMB; (B) H2O2 + CeO2 nanorods + TMB; (C) H2O2 + commercial CeO2 + TMB; (D) H2O2 + TMB.
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Fig. 8. The catalytic relative activity of CeO2 nanorods (square) and H2TCPP–CeO2 nancomposites (triangle) is pH- (a), temperature- (b) and H2O2 concentration- (c) dependent. The maximum point in each curve was set as 100%.
1.7 to 10.57 and the temperature from 25 °C to 60 °C. Moreover, we compared the results above with those of the peroxidase-like activity found in CeO2 in the same range of parameters. The effects of pH and temperature on the catalytic relative activity of H2TCPP–CeO2 nanocomposites and CeO2 nanorods toward TMB oxidation are shown in Fig. 8a
Fig. 9. The effect of the concentration of H2TCPP–CeO2 nanorods on the formation of hydroxyl radical with terephthalic acid as a fluorescence probe. A–H: no catalyst and no H2O2, 0 μg/ml, 50 μg/ml, 100 μg/ml, 150 μg/ml, 200 μg/ml, 250 μg/ml, 300 μg/ml. 10 mM H2O2, 0.5 mM terephthalic acid and different concentrations of the H2TCPP–NiO NPs were first incubated in CH3COONa buffer (pH 3.8) for 40 min.
and b. Very interestingly, the response curves in Fig. 8a show that the higher catalytic activity of CeO2 nanorods is pH 5 and pH 9.9, respectively. Because H2O2 can be easily decomposed into oxygen in alkaline solution, which would cause great error, the optimal conditions pH of CeO2 nanorods is 5 and 45 °C. Likewise, the optimal catalytic conditions of H2TCPP–CeO2 nanocomposites are pH 3.8 and 50 °C. The optimal pH 3.8 is very similar to the value for HRP in the previous report [9]. Thus, we adopted pH 3.8 and 50 °C as standard conditions for subsequent analysis of the H2TCPP–CeO2 nanocomposites. We found that the optimal concentration of H2O2 was 35 mM.
Scheme 2. Schematic energy level diagram and electron-transfer path from H2TCPP to CeO2.
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Fig. 10. The velocity (v) of the reaction was measured using 40 g CeO2 nanorods (a, e) or H2TCPP–CeO2 (b, d) in 1.4 ml of 0.12 M HAc pH 3.8 at room temperature. The concentration of TMB·2HCl was 0.05 mM and the H2O2 concentration was varied (a and b). The concentration of H2O2 was 25 mM and the TMB·2HCl concentration was varied (c and d). Double-reciprocal plots of activity of CeO2 nanorods H2TCPP–CeO2 at a fixed concentration of one substrate versus varying concentration of the second substrate for H2O2 and TMB (e, f, g and h). The y-axis values are observed absorbance values.
Q. Liu et al. / Materials Science and Engineering C 59 (2016) 445–453 Table 1 Comparison of the apparent Michaelis–Menten constant (Km) and maximum reaction rate (Vmax). Catalyst
H2TCPP–CeO2 CeO2 nanorods
Vm [10−9 M·s−1]
Km [10−5 M]
TMB
H2O2
TMB
H2O2
269 0.4014
4.96 2.59
1.06 7.53
36.6 95.8
3.4. Mechanism of catalysis The nature of peroxidase-like activities of the H2TCPP–CeO2 nanocomposites may originate from their catalytic ability to H2O2 decomposition into •OH radicals, being comfirmed with a fluorescent probe technique. To evidence this assumption, the •OH radical formation was assessed by adding the fluorescent probe terephthalic acid into the H2TCPP–CeO2 nanocomposite–H2O2 buffer system, where terephthalic acid easily reacted with •OH radicals to form highly fluorescent 2-hydroxy terephthalic acid [66]. Fig. 9 clearly shows gradual increasing of the fluorescence intensity with increasing of the concentration of the H2TCPP–CeO2 nanocomposites, suggesting that the amount of generated •OH radicals increased with the increase of H2TCPP–CeO2 nanocomposites. However, no fluorescence intensity can be observed in the absence of H2O2 at the identical conditions. These results indicated that H2TCPP–CeO2 nanocomposites could decompose H2O2 to •OH radicals, which is consistent with the behaviors of the CoFe2O4 NPs and ZnFe2O4 MNPs reported [67,68], while it was different from that of the reported Co3O4 NPs [69]. Therefore, the catalase-like activity of H2TCPP–CeO2 nanocomposites originated from the generation of •OH radicals. The catalytic activity of the Metal free H2TCPP toward H2O2 using TMB as a substrate. Unfortunately, pure porphyrin has not demonstrated the catalytic activity toward H2O2. Hence, as a useful photosensitizer, porphyrin in the nanocomposites plays an important synergistic role in catalyzing the oxidation of TMB in the presence of H2O2 [69b]. Scheme 2 is a schematic drawing illustrating the synergistic effect in the enhanced peroxidase-like activity over the H2TCPP–CeO2 composites. Under visible-light irradiation, the photoinduced electrons can easily be transferred from the conduction band (CB) of H2TCPP to the CB of CeO2 due to the lower CB level of CeO2 than that of H2TCPP [69b–e]. Furthermore, owing to the high conductivity of CeO2, the rate of electron transport is fast, which suppresses the direct recombination of photoinduced electron–hole pairs in the H2TCPP–CeO2 composite system. Thus, CeO2 acts as an acceptor of the photoinduced electrons from H2TCPP. Therefore, because of the presence of the H2TCPP–CeO2 interface, the chance of recombination of photoinduced electron–hole pairs is further successfully suppressed, leaving more charge carriers to
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form reactive species. The electrons in the CB of CeO2 could efficiently reduce the H2O2 adsorbed onto the composite catalyst surface into reactive species (•OH). Therefore, the enhanced peroxidase-like activity is achieved. 3.5. Steady-state kinetic analysis of the H2TCPP–CeO2 nanocomposites The peroxidase-like catalytic activity of the CeO2 nanorods and the H2TCPP–CeO2 nanocomposites was further comparatively investigated using steady-state kinetics (Fig. 10). Under the optimal conditions obtained above, the catalytic activity of H2TCPP–CeO2 nanocomposites was studied based on the enzyme kinetics theory using H2O2 and TMB as substrates. Within the suitable range of substrate concentrations, typical Michaelis–Menten curves were observed for both CeO2 nanorods (Fig. 10b, d, f and h) and H2TCPP–CeO2 nanocomposites (Fig. 10a, c, e and g). The kinetic data were fitted to the Michaelis–Menten model to obtain the parameters listed in Table 1. From Table 1, it can be seen that the apparent Km value of H2TCPP–CeO2 nanocomposites with H2O2 as the substrate was significantly higher than that of CeO2 nanorods and other reports [56], agreeing with the observation that a lower H2O2 concentration was required to achieve maximal activity for H2TCPP–CeO2 nanocomposites. The apparent Km value of the H2TCPP–CeO2 nanocomposites with TMB as the substrate was ca. seven times lower than CeO2 nanorods, indicating that the H2TCPP– CeO2 nanocomposites have a higher affinity for TMB than CeO2 nanorods. 3.6. Analytical application in determination of hydrogen peroxide and glucose The color variation of TMB oxidation catalyzed by H2TCPP–CeO2 nanocomposites was H2O2 concentration-dependent. Hence, quantitative detection of H2O2 could be performed on the basis of the absorbance change at 652 nm. Fig. 11a shows a typical H2O2 concentration response curve. The absorbance at 652 nm is proportional to H2O2 concentration from 0.01 to 0.1 mM with a detection limit (DL) of 6.1 × 10−6 mol·L−1. The linear regression equation is A = 0.27431 + 0.00143C (μM) and the correlation coefficient r is 0.9994. Since H2O2 is the main product of glucose oxidase (GOx)-catalyzed reaction, colorimetric detection of glucose with GOx can also be realized using H2TCPP–CeO2 nanocomposites. When the catalytic reaction is coupled with the glucose catalytic reaction by GOx, colorimetric determination of glucose can be readily realized. Fig. 11b shows a typical glucose concentration-response curve. Glucose can be detected as low as 3.3 × 10− 5 mol·L− 1, which was similar to the reported value that organic Fenton reaction was used for glucose detection [70], and the linear range is from 0.05 to 0.25 mM. The linear regression
Fig. 11. Linear calibration plot for H2O2 using H2TCPP–CeO2 nanorods as an artificial enzyme (a). Linear calibration plot for glucose detection using GOx and H2TCPP–CeO2 nanorods (b).
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The results of a fluorescence probe suggested that the nature of the peroxidase-like activity of the H2TCPP–CeO2 nanocomposites may originate from their catalytic ability to H2O2 decomposition into •OH radicals. When using GOx and the H2TCPP–CeO2 nanocomposites, the assay (pH 3.8, 50 °C) provided high sensitivity (3.3 × 10− 5 M) and selectivity for the detection of glucose. Based on this finding, we designed and developed a simple, cheap, highly selective and sensitive colorimetric assay to detect glucose in buffer solution. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (Grant No. 21271119), Key Laboratory of Photochemical Conversion and Optoelectronic Materials, TIPC, CAS (PCOM 201405), Science Foundation of Shandong Provincial Education Department (Grant No. J08LC11), and Research Progect of “SUST Spring Bud” (2008BWZ056). Fig. 12. Selective analysis of the assay using GOx and H2TCPP–CeO2 nancomposites for the detection of glucose. Inset: Insert: the corresponding color change of different samples. Concentration of solutes are 0.125 mM for glucose and 1.25 mM for the other glucose analogs.
equation is A = 0.06372 + 0.00027C (μM) and the correlation coefficient r is 0.994. Since glucose oxidase has high affinity to oxidized glucose [71–79], control experiments were carried out to test the selectivity of the developed system by using fructose, lactose, sucrose and maltose all at concentration of 1.25 mM instead of glucose at the concentration of 1.25 mM (Fig. 12). As shown in Fig. 12, the results demonstrated that the absorbance of these glucose analogs was much smaller than that of glucose, though the concentration of glucose analogs was 10 times higher that of glucose. The results implied the high selectivity to glucose of certain colorimetric assay. Corresponding color change could be observed by naked eye (the insert of Fig. 12). When compared to electrochemical biosensors, sensing system based on the H2TCPP– CeO2 nanocomposites showed comparable sensitivity and selectivity for glucose [80,81]. In our work, as for H2TCPP–CeO 2 nanocomposites, the LOD for H2O2 is 0.0061 mM, lower than that of Co3O4 [69] and Fe3O4 nanoparticles [11] while higher than that of Fe3 O4 nanocomposite in MMS-40 [82] and carbon dots [10]. Moreover, LOD for glucose is 0.033 mM, higher than that of other nanostructures listed in Table 2. This results shows that LOD for H2O2 and glucose are different, due to the different kinds, different morphologies and different sizes of nanomaterials. Furthermore, the LOD for H2O2 and glucose are also concerned with the catalytic mechanism of both hydroxyl radicals and electron transfer. 4. Conclusions H2TCPP functionalized CeO2 nancomposites were synthesized by a facile method. The H2TCPP–CeO2 nancomposites had a higher enzyme activity toward H2O2-mediated TMB reaction than those of HRP and CeO2 nanostuctures. We have found that the catalytic activity of the H2TCPP–CeO2 nancomposites is dependent on temperature and pH. Table 2 LOD for H2O2 and glucose using different nanomaterials, respectively. Nanomaterials
LOD for H2O2 (mM)
LOD for glucose (mM)
H2TCPP–CeO2 [our work] Fe3O4 nanocomposite in MMS-40 [82] Co3O4 nanoparticles [69] Carbon dots [10] Fe3O4 nanoparticles [11]
0.0061 0.0005 0.01 0.0002 0.03
0.033 0.003 0.005 0.0004 0.003
References [1] G. Liu, Y. Wan, V. Gau, J. Zhang, L.H. Wang, S.P. Song, C.H. Fan, J. Am. Chem. Soc. 130 (2008) 6820–6825. [2] F. Wen, Y.H. Dong, L. Feng, S. Wang, S.C. Zhang, X.R. Zhang, Anal. Chem. 83 (2011) 1193–1196. [3] P. Wu, Y. He, H.F. Wang, X.P. Yan, Anal. Chem. 82 (2010) 1427–1433. [4] Q. Zhao, X.F. Li, X.C. Le, Anal. Chem. 83 (2011) 9234–9236. [5] E. Shoji, M.S. Freund, J. Am. Chem. Soc. 123 (2001) 3383–3384. [6] R. Breslow, Acc. Chem. Res. 28 (1995) 146–153. [7] (a) K. Tian, M. Prestgard, A. Tiwari, Mater. Sci. Eng. C 41 (2014) 100–118; (b) D.L. Nelson, M.M. Cox, Lehninger Principles of Biochemistry, 4th ed. Freeman, New York, 2005 (Chapter 6). [8] Y.J. Song, X.H. Wang, C. Zhao, K.G. Qu, J.S. Ren, X.G. Qu, Chem. Eur. J. 16 (2010) 3617. [9] L.Z. Gao, J. Zhuang, L. Nie, J.B. Zhang, Y. Zhang, N. Gu, T. Wang, J. Feng, D. Yang, S. Perrett, X. Yan, Nat. Nanotechnol. 2 (2007) 577–583. [10] W.B. Shi, Q.L. Wang, Y.J. Long, Z.L. Cheng, S.H. Chen, H.Z. Zheng, Y.M. Huang, Chem. Commun. 47 (2011) 6695. [11] H. Wei, E. Wang, Anal. Chem. 80 (2008) 2250–2254. [12] X.Q. Zhang, S.W. Gong, Y. Zhang, T. Yang, C.Y. Wang, N. Gu, J. Mater. Chem. 20 (2010) 5110–5116. [13] W. Shi, X. Zhang, S. He, Y. Huang, Chem. Commun. 47 (2011) 10785–10787. [14] F. Yu, Y. Huang, A.J. Cole, V.C. Yang, Biomaterials 30 (2009) 4716–4722. [15] X. Zuo, C. Peng, Q. Huang, S. Song, L. Wang, D. Li, C. Fan, Nano Res. 2 (2009) 617–623. [16] S. Liu, F. Lu, R. Xing, J.J. Zhu, Chem. Eur. J. 17 (2011) 620–625. [17] H. Niu, D. Zhang, S. Zhang, X. Zhang, Z. Meng, Y. Cai, J. Hazard. Mater. 190 (2011) 559–565. [18] S. He, W. Shi, X. Zhang, J. Li, Y. Huang, Talanta 82 (2010) 377–383. [19] K.S. Park, M.I. Kim, D.Y. Cho, H.G. Park, Small 7 (2011) 1521–1525. [20] N. Wang, L. Zhu, M. Wang, D. Wang, H. Tang, Ultrason. Sonochem. 214 (2009) 4–9. [21] C. Korsvik, S. Patil, S. Seal, W.T. Self, Chem. Commun. (2007) 1056–1058. [22] M. Catauro, F. Bollino, F. Papale, M. Gallicchio, S. Pacifico, Mater. Sci. Eng. C 48 (2015) 548–555. [23] (a) E.G. Heckert, A.S. Karakoti, S. Seal, W.T. Self, Biomaterials 29 (2008) 2705–2709; (b) A. Asati, S. Santra, C. Kaittanis, S. Nath, J.M. Perez, Angew. Chem. Int. Ed. 48 (2009) 2308–2312. [24] T. Pirmohamed, J.M. Dowding, S. Singh, B. Wasserman, E. Heckert, A.S. Karakoti, J.E.S. King, S. Seal, W.T. Self, Chem. Commun. 46 (2010) 2736–2738. [25] R. Andre, F. Natalio, M. Humanes, J. Leppin, K. Heinze, R. Wever, H.C. Schroder, W.E.G. Muller, W. Tremel, Adv. Funct. Mater. 21 (2011) 501–509. [26] W. He, X. Wu, J. Liu, X. Hu, K. Zhang, S. Hou, W. Zhou, S. Xie, Chem. Mater. 22 (2010) 2988–2994. [27] Y. Jv, B. Li, R. Cao, Chem. Commun. 46 (2010) 8017–8019. [28] J. Fan, J.J. Yin, B. Ning, X. Wu, Y. Hu, M. Ferrari, G.J. Anderson, J. Wei, Y. Zhao, G. Nie, Biomaterials 32 (2011) 1611–1618. [29] W. He, Y. Liu, J. Yuan, J.J. Yin, X. Wu, X. Hu, K. Zhang, J. Liu, C. Chen, Y. Ji, Y. Guo, Biomaterials 32 (2011) 1139–1147. [30] J. Liu, X. Hu, S. Hou, T. Wen, W. Liu, X. Zhu, X. Wu, Chem. Commun. 47 (2011) 10981–10983. [31] X.X. Wang, Q. Wu, Z. Shan, Q.M. Huang, Biosens. Bioelectron. 26 (2011) 3614–3619. [32] Y. Song, K. Qu, C. Zhao, J. Ren, X. Qu, Adv. Mater. 22 (2010) 2206–2210. [33] Y. Song, X. Wang, C. Zhao, K. Qu, J. Ren, X. Qu, Chem. Eur. J. 16 (2010) 3617–3621. [34] R. Cui, Z. Han, J.J. Zhu, Chem. Eur. J. 17 (2011) 9377–9384. [35] F. Qu, T. Li, M. Yang, Biosens. Bioelectron. 26 (2011) 3927–3931. [36] W. Shi, Q. Wang, Y. Long, Z. Cheng, S. Chen, H. Zheng, Y. Huang, Chem. Commun. 47 (2011) 6695–6697. [37] Y. Song, Y. Chen, L. Feng, X. Qu, Chem. Commun. 47 (2011) 4436–4438. [38] X. Wang, K. Qu, B. Xu, J. Ren, X. Qu, Nano Res. 4 (2011) 908–920. [39] Y. Song, W. Wei, X. Qu, Adv. Mater. 23 (2011) 4215–4236. [40] R. Lloyd, R.L. Jenkins, M. Piccinini, Q. He, C.J. Kiely, A.F. Carley, S.E. Golunski, D. Bethell, J.K. Bartley, G.J. Hutchings, J. Catal. 283 (2011) 161–167. [41] J.D. Qiu, S.G. Cui, R.P. Liang, Mikrochim. Acta 171 (2010) 333–339.
Q. Liu et al. / Materials Science and Engineering C 59 (2016) 445–453 [42] Y.S. Chaudhary, S. Panigrahi, S. Nayak, B. Satpati, S. Bhattacharjee, N. Kulkarni, J. Mater. Chem. 20 (2010) 2381–2385. [43] K. Yung Jun, K.O. Joong, K. Min Cheol, S. Myung Won, I. Young, K. Jae Jeong, J. Electrochem. Soc. 157 (2010) 952–958. [44] Y. Xuan, J. Hu, K. Xu, X. Hou, Y. Lv, Sensors Actuators B 136 (2009) 218–223. [45] L. Liao, H.X. Mai, Q. Yuan, H.B. Lu, J.C. Li, C. Liu, C.H. Yan, Z.X. Shen, T. Yu, J. Phys. Chem. C 112 (2008) 9061–9065. [46] P. Fornasiero, A. Speghini, R. Di Monte, M. Bettinelli, J. Kaspar, A. Bigotto, V. Sergo, M. Graziani, Chem. Mater. 16 (2004) 1938–1944. [47] J.P. Chen, S. Patil, S. Seal, J.F. McGinnis, Nat. Nanotechnol. 1 (2006) 142. [48] R.W. Tarnuzzer, J. Colon, S. Patil, S. Seal, Nano Lett. 5 (2005) 2573. [49] J. Niu, A. Azfer, L.M. Rogers, X. Wang, P.E. Kolattukudy, Cardiovasc. Res. 73 (2007) 549. [50] M. Das, S. Patil, N. Bhargava, J.F. Kang, L.M. Riedel, S. Seal, J.J. Hickman, Biomaterials 28 (2007) 1918. [51] X. Xiao, Q. Luan, X. Yao, K. Zhou, Biosens. Bioelectron. 24 (2009) 2447–2451. [52] D. Schubert, R. Dargusch, J. Raitano, S.W. Chan, Biochem. Biophys. Res. Commun. 342 (2006) 86–91. [53] A. Karakoti, S. Singh, J.M. Dowding, S. Sealand, W.T. Self, Chem. Soc. Rev. 39 (2010) 4422–4432. [54] T. Pirmohamed, J.M. Dowding, S. Singh, B. Wasserman, E. Heckert, A.S. Karakoti, J.E.S. King, S. Seal, W.T. Self, Chem. Commun. 46 (2010) 2736. [55] X. Xiao, Q. Luan, X. Yao, K. Zhou, Biosens. Bioelectron. 24 (2009) 2447–2451. [56] X. Jiao, H.J. Song, H.H. Zhao, W. Bai, L.C. Zhang, Anal. Methods 4 (2012) 3261. [57] K. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, Academic Press, New York, 1999. [58] A.D. Adler, F.R. Longo, J.D. Finarelli, J. Goldmacher, J. Assour, L. Korsakoff, J. Org. Chem. 32 (1967) 476. [59] B. Tang, L.H. Zhuo, J.C. Ge, G.L. Wang, Chem. Commun. (2005) 3565–3567. [60] Q. Wang, Y. Chen, P. Ma, J. Lu, X. Zhang, J. Jiang, J. Mater. Chem. 21 (2011) 8057–8065. [61] G. Lu, X. Zhang, X. Cai, J. Jiang, J. Mater. Chem. 19 (2009) 2417–2424. [62] A.W. Snow, in: K.M. Kadish, R. Smith (Eds.), The Porphyrin Handbook, Guilard, Elsevier Science 2003, p. 129. [63] M. Kasha, H.R. Rawls, M.A. El-Bayoumi, Pure Appl. Chem. 11 (1965) 371.
453
[64] P. Burroughs, A. Hamnett, A.F. Orchard, G. Thornton, J. Chem. Soc. Dalton Trans. (1976) 1686–1698. [65] B. Li, Y. Du, T. Li, S. Dong, Anal. Chim. Acta 651 (2009) 234–240. [66] K. Ishibashi, A. Fujishima, T. Watanabe, K. Hashimoto, J. Photochem. Photobiol. A 134 (2000) 139–142. [67] L. Su, J. Feng, X.M. Zhou, C.L. Ren, H.H. Li, X.G. Chen, Anal. Chem. 84 (2012) 5753–5758. [68] W.B. Shi, X.D. Zhang, S.H. He, Y.M. Huang, Chem. Commun. 47 (2011) 10785–10787. [69] (a) J.S. Mu, Y. Wang, M. Zhao, L. Zhang, Chem. Commun. 48 (2012) 2540–2542; (b) Q. Liu, Y. Yang, H. Li, R. Zhu, Q. Shao, S. Yang, J. Xu, Biosens. Bioelectron. 64 (2015) 147–153; (c) N. Wetchakun, S. Chaiwichain, B. Inceesungvorn, K. Pingmuang, S. Phanichphant, A.I. Minett, J. Chen, ACS Appl. Mater. Interfaces 4 (2012) 3718–3723; (d) J. Roh, S.H. Hwang, J. Jang, ACS Appl. Mater. Interfaces 6 (2014) 19825–19832; (e) W.W. Tu, J.P. Lei, P. Wang, H.X. Ju, Chem. Eur. J. 17 (2011) 9440–9447. [70] X. Xu, X. Yang, Anal. Methods 3 (2011) 1056–1059. [71] E.S. Forzani, H.Q. Zhang, L.A. Nagahara, I. Amlani, R. Tsui, N. Tao, Nano Lett. 4 (2004) 1785. [72] R. Gill, L. Bahshi, R. Freeman, I. Willner, Angew. Chem. Int. Ed. 47 (2008) 1676. [73] H. Wei, E. Wang, Anal. Chem. 80 (2008) 2250. [74] V. Sanz, S. de Marcos, J.R. Castillo, J. Galban, J. Am. Chem. Soc. 127 (2005) 1038. [75] R. Kurita, H. Tabei, Y. Iwasaki, K. Hayashi, K. Sunagawa, O. Niwa, Biosens. Bioelectron. 20 (2004) 518. [76] P.F. Pang, Y.L. Zhang, S.T. Ge, Q.Y. Cai, S.Z. Yao, C.A. Grimes, Sensors Actuators B Chem. 136 (2009) 310. [77] H.S.M. Abd-Rabboh, M.E. Meyerhoff, Talanta 72 (2007) 1129. [78] S. Cosnier, F. Lambert, M. Stoytcheva, Electroanalysis 12 (2000) 356. [79] K. Abe, K. Suzuki, D. Citterio, Anal. Chem. 80 (2008) 6928. [80] Y.X. Li, X.Q. Lin, Sensors Actuators B 115 (2006) 134–139. [81] J. Wang, Electroanalysis 17 (2005) 7–14. [82] M. Kim, J. Shim, T. Li, J. Lee, H.G. Park, Chem. Eur. J. 17 (2011) 10700–10707.
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Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec
Enhanced peroxidase-like activity of porphyrin functionalized ceria nanorods for sensitive and selective colorimetric detection of glucose Qingyun Liu ⁎, Yanyuan Ding, Yanting Yang, Leyou Zhang, Lifang Sun, Pengpeng Chen, Chun Gao School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510, PR China
a r t i c l e
i n f o
Article history: Received 6 April 2015 Received in revised form 18 September 2015 Accepted 15 October 2015 Available online 17 October 2015 Keywords: Porphyrin CeO2 nanorods Colorimetric Nanocomposites Peroxidase
a b s t r a c t Ceria nanorods modified with 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H2TCPP) were prepared. These nanocomposites (H2TCPP–CeO2) exhibited the intrinsic peroxidase-like activity and could catalyze the oxidation of classical peroxidase substrate 3,3′,5,5′-tetramethylbiphenyl dihydrochloride (TMB·2HCl) in the presence of H2O2 to produce a typical color reaction from colorless to blue. Our results demonstrated that both the H2TCPP–CeO2 nanocomposites and CeO2 nanorods exhibited higher thermal durance than that of HRP. The affinity of The H2TCPP–CeO2 nanocomposites toward H2O2 and TMB is similar to that of HRP. Fluorescent results indicated that the catalytic mechanism of the H2TCPP–CeO2 nanocomposites were from the decomposition of H2O2 into hydroxyl radicals. Based on these studies, a simple, sensitive, and selective visual and colorimetric method using TMB as the substrate was designed to detect glucose when combined with glucose oxidase. The proposed colorimetric method can detect H2O2 at a low detection limit of 6.1 × 10−6 M and a dynamic range of 10−5–10−4 mol·L−1. This method can also detect glucose at a low detection limit of 3.3 × 10−5 mol·L−1 and a dynamic range of 5.0 × 10−5–1.0 × 10−4 mol·L−1. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Enzymes are efficient biological catalysts, which are involved in almost all reactions. Natural enzymes with high substrate specificity and high catalytic efficiency play central roles in a wide range of applications, such as clinical diagnosis, biotechnology, chemistry, and environmental science, and have been extensively studied for more than 200 years [1–4]. Unfortunately, the intrinsic drawbacks of their easy denaturation [5] and high costs in preparation and purification [6] limit their large scale applications. To overcome the limitations of natural enzymes, intense interest has grown in the development of nonenzymatic glucose sensors [7a] and artificial enzyme mimetics [7b]. Nanomaterials are attractive and are widely put to use because of their unique optical, electronic, magnetic, and catalytic properties [8]. In 2007, the excitingly intrinsic peroxidase-like activity of ferromagnetic nanoparticles, an inert nanomaterial, was reported [9] and aroused people's attention for the innovative research of nanomaterials in the enzyme mimetic field [10]. Various nanoparticles have been evaluated as enzymatic mimetics [11–39], including ferromagnetic NPs with peroxidase-like activity [11–20], ceria oxide NPs [21–24] and V2O5 nanowires [25] with oxidase mimetic properties, metal nanoparticles with oxidase or peroxidase-like activity [26–31], SiO2/PEG hybrid materials [22] and carbon-based nanomaterials. [23–39].
⁎ Corresponding author. E-mail addresses: [email protected], [email protected] (Q. Liu).
http://dx.doi.org/10.1016/j.msec.2015.10.046 0928-4931/© 2015 Elsevier B.V. All rights reserved.
Nanoceria, as an important rare-earth oxide nanostructure material, has attracted enormous interest in recent years, due to the unique physical and chemical properties compared with that of its bulk materials. Therefore, it has been widely applied in various areas, including catalysis, electrochemistry, photochemistry, metal polishing agent, fuel cells, gas sensors and luminescence [40–46]. In recent studies, cerium oxide nanoparticles (nanoceria) are found to be the potent free-radical scavengers as well as exhibit neuroprotective, radioprotective, and anti-inflammatory properties [47–49]. Nanoceria also have the unique property of being regenerative or autocatalytic [50]. In addition, the novel properties of nanomaterials are associated with their size, shape and morphology, such as sphere, rod, polyhedral, and cubic. [51–53]. Nanoceria with the higher level of Ce4+ oxidation state exhibited significant catalase-mimetic activity, while those with the higher level of Ce3+ oxidation state did not, so the decomposition of H2O2 to oxygen by nanoceria depended on the ratio of Ce3+/Ce4+, which could be modulated by morphology, H2O2 and phosphate solutions (e.g., phosphate buffered saline) [54] to improve catalase-mimetic activity. A new horseradish peroxidase (HRP) third-generation electrochemical biosensor based on ceria nanocubes has been established [55]. CeO2 nanoparticles can be used to detect glucose in human blood serum samples by colorimetric method [56]. However, the ceria nanostructures that have been investigated so far for their peroxidase mimetic activity have had zero dimensional shape. Porphyrin, tetrapyrrole derivatives as the representatives of functional molecular materials with large conjugated electronic molecular
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structures, have attracted great research interest in vastly diverse areas ranging from chemistry, physics, biology, and medicine to molecular device [57]. Porphyrins widely exist in organism and the energy transfer of the relevant important organelles. If we can obtain the functional porphyrin-ceria nanocomposites, it will provide excellent opportunities for applications in the fields of artificial enzyme mimetics, biosensor, electrocatalysis, luminescence, electronics, etc. However, to the best of our knowledge, one dimensional ceria nanorods as well as 5,10,15,20tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) modified ceria nanorods have not been reported thus far. In this paper, H2TCPP modified CeO2 nanorods were prepared by a facile two-step method. Interestingly, the as-prepared CeO2 nanorods and H2TCPP–CeO2 nanocomposites demonstrated peroxidase-like activity that they could catalyze oxidation of the substrate 3,3′,5,5′ertramethylbenzidine dihydrochloride (TMB·2HCl) in the presence of H2O2. Furthermore, the catalytic activity of H2TCPP–CeO2 nanocomposite showed much higher than that of pure CeO2 nanorods. As a result, H2TCPP–CeO2 nanocomposites were used as mimic enzyme by a colorimetric method for H2O2 detection. And we all know that the oxidation of glucose could be catalyzed by glucose oxidase (GOx) in the presence of oxygen to produce gluconic acid and H2O2. Therefore, a simple, sensitive and cheap colorimetric method has been developed for glucose detection (Scheme 1). The results indicate that this method is higher sensitive and selective for the detection of glucose and can be successfully used in the quantitative detection of glucose in buffer solution and even in human serum system. 2. Experimental section 2.1. Chemicals and reagents Cerium nitrate hexahydrate (Ce(NO3)3·6H2O), hydrogen peroxide (30 wt.%,H2O2), acetic acid (HAc), sodium acetate(NaAc), TMB·2HCl, glucose, fructose, lactose, and mannitol were purchased from Guangcheng Reagent Co. (Tianjin, China). Glucose oxidase (GOx, ≥200 U mg−1) was purchased from Sigma-Aldrich and stored in a refrigerator at −18 °C. All the regents were of analytical reagent grade and used without further purification. 5,10,15,20-Tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) was synthesized according to the previous literature [58]. 2.2. Preparation of CeO2 nanorods and porphyrin functionalized CeO2 nanocomposites (H2TCPP–CeO2) CeO2 nanorods were prepared according to a previous report [59]. In a typical procedure, Ce(NO3)3 (8 ml, 0.05 M) was added rapidly to H2O2 (8 ml, 30.0%) solution and stirred for ca. 10 min. The suspension was transferred into a 25 ml Teflon-lined autoclave, which was heated at 250 °C for 3 h. The system was then allowed to cool to room temperature naturally. The final product was washed with deionized water,
and dried at 60 °C for 12 h. Then CeO2 nanorods were obtained. Subsequently, the CeO2 nanorods was dissolved into 5 mM H2TCPP solution (pH = 8) was treated to an ultrasonic water bath for 1.5 h. The sample (H2TCPP–CeO2) was washed with NaOH solution (pH = 8) and dried at room temperature in air. The target product was successfully obtained and studied in the subsequent experiment.
2.3. Characterization The morphology and size distribution of the nanorods were imaged by transmission electron microscope (TEM JEM-2100, JEOL, Japan). The crystal structures of the products were determined by powder X-ray diffraction (XRD) patterns with graphite monochromatized Cu Kα radiation (D/Max2500PC, Rigaku, Japan). Fourier transform infrared (FTIR) spectra were taken in KBr pressed pellets on a NICOLET 380 FTIR spectrometer (Nicolet Thermo, USA). UV–vis absorption spectra were recorded on a MAPADA UV-3200PC spectrophotometer (Shanghai, China). X-ray photoelectron spectra (XPS) were recorded on a PHI Quantera SXM spectrometer with an Al Kα = 280.00 eV excitation source, and binding energies were calibrated by referencing the C1s peak (284.5 eV) to reduce the sample charge effect.
2.4. Mechanism of peroxidase-like activity of H2TCPP–CeO2 nanorods We presume that the nature of peroxidase-like activities of the H2TCPP–CeO2 nanorods may originate from their catalytic ability to H2O2 decomposition into •OH radicals. So we used a method of fluorescence to measure the •OH radicals with terephthalic acid as probe. The typical experimental procedure is as follows: H2O2 (10 mM), terephthalic acid (0.5 mM) and the CeO2 nanorods with different concentrations (0, 50, 100, 150, 200, 250, 300 μg/ml) were first incubated in acetate buffer (pH 3.8, 100 mM) at 40 °C for 40 min. After centrifugation, the solutions were used for fluorometric measurement by a Cary Eclipse spectrofluorophotometer (Varian, Inc., USA).
2.5. Kinetic analysis The reaction kinetic measurements were carried out in time course mode by monitoring the absorbance variation at 652 nm with a 1 s interval on a MAPADA UV-3200PC spectrophotometer. The experiments were carried out with 0.04 mg·mL−1 H2TCPP–CeO2 solution or 0.04 mg·mL− 1 CeO2 in reaction buffer (0.026 M NaAc, pH 3.8) with TMB·2HCl as substrate; H2O2 concentration was 25 mM for CeO2 and H2TCPP–CeO2 nanorods. The Michaelis–Menten constant was calculated according to the Michaelis–Menten eqn (1): v = Vmax [S] / (Km + [S]), where v is the initial velocity, [S] is the concentration of substrate, Km is the Michaelis constant and Vmax is the maximal reaction velocity.
2.6. H2O2 and glucose detection
Scheme 1. Schematic illustration of oxidation of glucose by GOx.
In a typical process, the solution of hydrogen peroxide with a given concentration was added to TMB (final concentration of 0.25 mM) solution in the presence of H2TCPP–CeO2 nanocomposites solution (final concentration of 0.02 mg·mL−1) and the NaAc buffer (pH 3.8). The mixture was incubated at room temperature for 10 min. Glucose detection was realized as follows: a) 100 μl of 0.5 mg·mL− 1 GOx and 500 μL of glucose of different concentrations in PBS (pH 7.0) were incubated at 37 °C for 0.5 h; b) 200 μL of 0.5 mM TMB, 30 μL of the H2TCPP–CeO2 nanocomposites solution, and 1.17 mL of buffer (pH 3.8) were added into the above 200 μL glucose reaction solution. The mixed solution was used to perform the time course measurement.
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Fig. 1. Powder X-ray diffraction pattern of the as-prepared samples (A, CeO2 nanorods; B, H2TCPP–CeO2 nanocomposites).
3. Results and discussion 3.1. Characterization of as-synthesized CeO2 nanorods and H2TCPP–CeO2 nanocomposites Fig. 1 shows the XRD pattern of the obtained CeO2 nanorods (Fig. 1A) and that of H2TCPP–CeO2 nanocomposites (Fig. 1B). The diffraction peaks observed show a good match with CeO2 (JCPDS 34-0394), indicating that the prepared CeO2 nanorods have a cubic, fluorite-type structure and high purity. However, expect for the corresponding diffraction peak of CeO2 crystal, a weak diffraction peak located 22.0° (d = 0.404 nm) was observed in the XRD pattern of H2TCPP–CeO2 nanorods, due to the H2TCPP aggregates on the surface of CeO2 nanorods through coordination, adsorption and π–π supramolecular interactions [60–61]. The morphology and size of the obtained CeO2 nanorods (occasionally found less CeO2 nanoparticles) and H2TCPP–CeO2 nanocomposites were imaged by Transmission electron microscopy (TEM), shown in Fig. 2. TEM images showed freshly synthesized CeO2 nanorods with a variable size from 24 nm up to several hundred nm in length and average 21 nm in width. The morphologies of H2TCPP–CeO2 nanocomposites were also similar to those of CeO2 nanorods, suggesting that a few H2TCPP molecules were attached on the surface of CeO2 nanorods through coordination between H2TCPP molecules and CeO2 together with π–π superamolecular interactions existed in interporphyrin
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Fig. 3. FTIR spectra of the as-prepared H2TCPP–CeO2 nanocomposites (A) and H2TCPP (B).
molecules, which further confirmed by the spectra of FI-IR and UV–vis in the subsequent experiments. The H2TCPP functionalized CeO2 was further confirmed by FI-IR and UV–vis absorption spectra, respectively. The infrared spectra of H2TCPP–CeO2 nanocomposites and H2TCPP are shown in Fig. 3A and B, respectively. The infrared spectrum of H2TCPP–CeO2 nanocomposites is different from that of the pure H2TCPP. The spectrum showed that 1697 cm−1 attributed to the vibration peak of carbonyl group attached on macrocycles of porphyrin disappeared, compared with that of H2TCPP, which verified the coordination interaction existed between carbonyl groups from H2TCPP molecules and CeO2 nanorods. Moreover, the stretching vibration at ca. 1640 cm−1 and 1540 cm−1 assigned as the C _C bonds and C_N double bond that become broader. Fig. 3 shows a broad and intense peak characteristic of O–H groups centered at 3426 cm−1 (H2TCPP) and 3400 cm−1 (H2TCPP–CeO2). Thus, the FTIR data verified that the coordination interaction existed between H2TCPP molecules and CeO2 nanorods. Fig. 4 shows the UV–vis electronic absorption spectra of dilute DMF solution of H2TCPP (A), H2TCPP–CeO2 nanocomposites (B) and CeO2 nanorods (C) dispersed in ultrapure water, respectively. From the figure, it can be seen that H porphyrin–porphyrin stacking modes of H2TCPP–CeO2 nanocomposites (B) can be easily achieved by electronic absorption spectroscopic examination, because the absorption peak of H2TCPP–CeO2 nanocomposites at 413 nm with 6 nm blue-shift, compared with that of the dilute DMF solution of H2TCPP monomolecule at 419 nm (A). This result revealed intensive inter-molecular interaction
Fig. 2. TEM images of the CeO2 nanorods (A) and the H2TCPP–CeO2 nanorods (B).
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Fig. 6. A comparison of the catalytic activities of different materials in the peroxidase-like oxidation of TMB in NaAc buffer solution (pH 3.8) after 15 min. (Sample specifications: A: H2O2 + commercial CeO2 + TMB, B: H2O2 + CeO2 nanrods + TMB, C: H2O2 + H2TCPP– CeO2 nanocomposites + TMB, D: H2TCPP–CeO2 nanocomposites + TMB, E: H2O2 + TMB, F. H2TCPP–CeO2 nanocomposites, G. TMB).
Fig. 4. The UV–vis absorption spectra of the dilute DMF solution of H2TCPP (A), H2TCPP– CeO2 nanocomposites dispersed in pure water (B) and CeO2 nanorods (C), respectively.
of porphyrin molecules together with coordination interaction between H2TCPP and CeO2 in the nanocomposites [62–63]. It can also be seen that the similarity in the electronic absorption spectra both the nanorods dispersed in pure water and the dilute DMF solution of H2TCPP gives an unambiguous evidence for one of the composition of the nanocomposites from the porphyrin molecules. The Ce 3d electron core level XPS spectrum for as-prepared CeO2 nanorods is shown in Fig. 5. The XPS spectrum from cerium is complex and splits into Ce 3d3/2 and Ce 3d5/2 with multiple shake-up and shakedown satellites. The peaks between 895 and 910 eV correspond to the Ce 3d3/2 while peaks between 875 and 895 eV belong to the Ce 3d5/2 levels [64]. Greater intensity peaks corresponding to Ce4 + were observed in sample, revealing a higher Ce4+/Ce3+ ratio. XPS analysis indicates that a slight reduced surface of the CeO2 nanorods could be obtained according a simple hydrothermal method.
3.2. Peroxidase-like activity of H2TCPP–CeO2 nanocomposites
photographs of different reaction systems. It can be observed that additional control experiments using TMB in the absence of H2TCPP–CeO2 composite or H2O2 show no obvious color change, indicating that the two components are required for the reaction (Fig. 6). It can also be seen that the catalytic activity of CeO2 nanorods modified with H2TCPP was much higher than that of commercial CeO2 and CeO2 nanorods alone, revealing that an activated sample of H2TCPP–CeO2 exhibited enhanced peroxidase-like catalytic activity under identical conditions. The time-dependent UV–vis spectra of different reaction systems at room temperature were shown in Fig. 7. The absorbance of the H2TCPP– CeO2 nanocomposite–TMB–H2O2 system at 652 nm was much higher than that of H2O2–CeO2 nanorod–TMB, H2O2–commercial CeO2–TMB and H2O2–TMB system. Other than the different morphologies of CeO2 nanostructures reported [56], most important of all, it is due to the introduction of H2TCPP molecules on the surface of CeO2 nanorods. 3.3. Optimization of the experimental conditions The catalytic relative activity of H2TCPP–CeO2 nanocomposites is dependent on pH, temperature and the concentration of H2O2, which is very similar to that of HRP and the reported CeO2 NPs [56]. The peroxidase-like activities of H2TCPP–CeO2 nanocomposites toward the oxidation of TMB by H2O2 was investigated while varying the pH from
To investigate the peroxidase-like activity of H2TCPP–CeO2 nanocomposites, the catalysis of peroxidase substrate TMB was tested in the presence of H2O2. The oxidation of TMB has a characteristic absorbance at 652 nm and corresponding blue color [65]. Fig. 6 shows
Fig. 5. Raw XPS spectrum of as-prepared CeO2 nanorods.
Fig. 7. Time-dependent absorbance changes at 652 nm of TMB in different systems. In this experiment, H2TCPP–CeO2 nanocomposite concentration: 40 μg/ml, TMB concentration: 0.05 mM, H2O2 concentration: 25 mM, the concentration of acetate buffer solution (pH = 3.8): 0.12 M.: (A) H2O2 + H2TCPP–CeO2 nanocomposites + TMB; (B) H2O2 + CeO2 nanorods + TMB; (C) H2O2 + commercial CeO2 + TMB; (D) H2O2 + TMB.
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Fig. 8. The catalytic relative activity of CeO2 nanorods (square) and H2TCPP–CeO2 nancomposites (triangle) is pH- (a), temperature- (b) and H2O2 concentration- (c) dependent. The maximum point in each curve was set as 100%.
1.7 to 10.57 and the temperature from 25 °C to 60 °C. Moreover, we compared the results above with those of the peroxidase-like activity found in CeO2 in the same range of parameters. The effects of pH and temperature on the catalytic relative activity of H2TCPP–CeO2 nanocomposites and CeO2 nanorods toward TMB oxidation are shown in Fig. 8a
Fig. 9. The effect of the concentration of H2TCPP–CeO2 nanorods on the formation of hydroxyl radical with terephthalic acid as a fluorescence probe. A–H: no catalyst and no H2O2, 0 μg/ml, 50 μg/ml, 100 μg/ml, 150 μg/ml, 200 μg/ml, 250 μg/ml, 300 μg/ml. 10 mM H2O2, 0.5 mM terephthalic acid and different concentrations of the H2TCPP–NiO NPs were first incubated in CH3COONa buffer (pH 3.8) for 40 min.
and b. Very interestingly, the response curves in Fig. 8a show that the higher catalytic activity of CeO2 nanorods is pH 5 and pH 9.9, respectively. Because H2O2 can be easily decomposed into oxygen in alkaline solution, which would cause great error, the optimal conditions pH of CeO2 nanorods is 5 and 45 °C. Likewise, the optimal catalytic conditions of H2TCPP–CeO2 nanocomposites are pH 3.8 and 50 °C. The optimal pH 3.8 is very similar to the value for HRP in the previous report [9]. Thus, we adopted pH 3.8 and 50 °C as standard conditions for subsequent analysis of the H2TCPP–CeO2 nanocomposites. We found that the optimal concentration of H2O2 was 35 mM.
Scheme 2. Schematic energy level diagram and electron-transfer path from H2TCPP to CeO2.
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Fig. 10. The velocity (v) of the reaction was measured using 40 g CeO2 nanorods (a, e) or H2TCPP–CeO2 (b, d) in 1.4 ml of 0.12 M HAc pH 3.8 at room temperature. The concentration of TMB·2HCl was 0.05 mM and the H2O2 concentration was varied (a and b). The concentration of H2O2 was 25 mM and the TMB·2HCl concentration was varied (c and d). Double-reciprocal plots of activity of CeO2 nanorods H2TCPP–CeO2 at a fixed concentration of one substrate versus varying concentration of the second substrate for H2O2 and TMB (e, f, g and h). The y-axis values are observed absorbance values.
Q. Liu et al. / Materials Science and Engineering C 59 (2016) 445–453 Table 1 Comparison of the apparent Michaelis–Menten constant (Km) and maximum reaction rate (Vmax). Catalyst
H2TCPP–CeO2 CeO2 nanorods
Vm [10−9 M·s−1]
Km [10−5 M]
TMB
H2O2
TMB
H2O2
269 0.4014
4.96 2.59
1.06 7.53
36.6 95.8
3.4. Mechanism of catalysis The nature of peroxidase-like activities of the H2TCPP–CeO2 nanocomposites may originate from their catalytic ability to H2O2 decomposition into •OH radicals, being comfirmed with a fluorescent probe technique. To evidence this assumption, the •OH radical formation was assessed by adding the fluorescent probe terephthalic acid into the H2TCPP–CeO2 nanocomposite–H2O2 buffer system, where terephthalic acid easily reacted with •OH radicals to form highly fluorescent 2-hydroxy terephthalic acid [66]. Fig. 9 clearly shows gradual increasing of the fluorescence intensity with increasing of the concentration of the H2TCPP–CeO2 nanocomposites, suggesting that the amount of generated •OH radicals increased with the increase of H2TCPP–CeO2 nanocomposites. However, no fluorescence intensity can be observed in the absence of H2O2 at the identical conditions. These results indicated that H2TCPP–CeO2 nanocomposites could decompose H2O2 to •OH radicals, which is consistent with the behaviors of the CoFe2O4 NPs and ZnFe2O4 MNPs reported [67,68], while it was different from that of the reported Co3O4 NPs [69]. Therefore, the catalase-like activity of H2TCPP–CeO2 nanocomposites originated from the generation of •OH radicals. The catalytic activity of the Metal free H2TCPP toward H2O2 using TMB as a substrate. Unfortunately, pure porphyrin has not demonstrated the catalytic activity toward H2O2. Hence, as a useful photosensitizer, porphyrin in the nanocomposites plays an important synergistic role in catalyzing the oxidation of TMB in the presence of H2O2 [69b]. Scheme 2 is a schematic drawing illustrating the synergistic effect in the enhanced peroxidase-like activity over the H2TCPP–CeO2 composites. Under visible-light irradiation, the photoinduced electrons can easily be transferred from the conduction band (CB) of H2TCPP to the CB of CeO2 due to the lower CB level of CeO2 than that of H2TCPP [69b–e]. Furthermore, owing to the high conductivity of CeO2, the rate of electron transport is fast, which suppresses the direct recombination of photoinduced electron–hole pairs in the H2TCPP–CeO2 composite system. Thus, CeO2 acts as an acceptor of the photoinduced electrons from H2TCPP. Therefore, because of the presence of the H2TCPP–CeO2 interface, the chance of recombination of photoinduced electron–hole pairs is further successfully suppressed, leaving more charge carriers to
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form reactive species. The electrons in the CB of CeO2 could efficiently reduce the H2O2 adsorbed onto the composite catalyst surface into reactive species (•OH). Therefore, the enhanced peroxidase-like activity is achieved. 3.5. Steady-state kinetic analysis of the H2TCPP–CeO2 nanocomposites The peroxidase-like catalytic activity of the CeO2 nanorods and the H2TCPP–CeO2 nanocomposites was further comparatively investigated using steady-state kinetics (Fig. 10). Under the optimal conditions obtained above, the catalytic activity of H2TCPP–CeO2 nanocomposites was studied based on the enzyme kinetics theory using H2O2 and TMB as substrates. Within the suitable range of substrate concentrations, typical Michaelis–Menten curves were observed for both CeO2 nanorods (Fig. 10b, d, f and h) and H2TCPP–CeO2 nanocomposites (Fig. 10a, c, e and g). The kinetic data were fitted to the Michaelis–Menten model to obtain the parameters listed in Table 1. From Table 1, it can be seen that the apparent Km value of H2TCPP–CeO2 nanocomposites with H2O2 as the substrate was significantly higher than that of CeO2 nanorods and other reports [56], agreeing with the observation that a lower H2O2 concentration was required to achieve maximal activity for H2TCPP–CeO2 nanocomposites. The apparent Km value of the H2TCPP–CeO2 nanocomposites with TMB as the substrate was ca. seven times lower than CeO2 nanorods, indicating that the H2TCPP– CeO2 nanocomposites have a higher affinity for TMB than CeO2 nanorods. 3.6. Analytical application in determination of hydrogen peroxide and glucose The color variation of TMB oxidation catalyzed by H2TCPP–CeO2 nanocomposites was H2O2 concentration-dependent. Hence, quantitative detection of H2O2 could be performed on the basis of the absorbance change at 652 nm. Fig. 11a shows a typical H2O2 concentration response curve. The absorbance at 652 nm is proportional to H2O2 concentration from 0.01 to 0.1 mM with a detection limit (DL) of 6.1 × 10−6 mol·L−1. The linear regression equation is A = 0.27431 + 0.00143C (μM) and the correlation coefficient r is 0.9994. Since H2O2 is the main product of glucose oxidase (GOx)-catalyzed reaction, colorimetric detection of glucose with GOx can also be realized using H2TCPP–CeO2 nanocomposites. When the catalytic reaction is coupled with the glucose catalytic reaction by GOx, colorimetric determination of glucose can be readily realized. Fig. 11b shows a typical glucose concentration-response curve. Glucose can be detected as low as 3.3 × 10− 5 mol·L− 1, which was similar to the reported value that organic Fenton reaction was used for glucose detection [70], and the linear range is from 0.05 to 0.25 mM. The linear regression
Fig. 11. Linear calibration plot for H2O2 using H2TCPP–CeO2 nanorods as an artificial enzyme (a). Linear calibration plot for glucose detection using GOx and H2TCPP–CeO2 nanorods (b).
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The results of a fluorescence probe suggested that the nature of the peroxidase-like activity of the H2TCPP–CeO2 nanocomposites may originate from their catalytic ability to H2O2 decomposition into •OH radicals. When using GOx and the H2TCPP–CeO2 nanocomposites, the assay (pH 3.8, 50 °C) provided high sensitivity (3.3 × 10− 5 M) and selectivity for the detection of glucose. Based on this finding, we designed and developed a simple, cheap, highly selective and sensitive colorimetric assay to detect glucose in buffer solution. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (Grant No. 21271119), Key Laboratory of Photochemical Conversion and Optoelectronic Materials, TIPC, CAS (PCOM 201405), Science Foundation of Shandong Provincial Education Department (Grant No. J08LC11), and Research Progect of “SUST Spring Bud” (2008BWZ056). Fig. 12. Selective analysis of the assay using GOx and H2TCPP–CeO2 nancomposites for the detection of glucose. Inset: Insert: the corresponding color change of different samples. Concentration of solutes are 0.125 mM for glucose and 1.25 mM for the other glucose analogs.
equation is A = 0.06372 + 0.00027C (μM) and the correlation coefficient r is 0.994. Since glucose oxidase has high affinity to oxidized glucose [71–79], control experiments were carried out to test the selectivity of the developed system by using fructose, lactose, sucrose and maltose all at concentration of 1.25 mM instead of glucose at the concentration of 1.25 mM (Fig. 12). As shown in Fig. 12, the results demonstrated that the absorbance of these glucose analogs was much smaller than that of glucose, though the concentration of glucose analogs was 10 times higher that of glucose. The results implied the high selectivity to glucose of certain colorimetric assay. Corresponding color change could be observed by naked eye (the insert of Fig. 12). When compared to electrochemical biosensors, sensing system based on the H2TCPP– CeO2 nanocomposites showed comparable sensitivity and selectivity for glucose [80,81]. In our work, as for H2TCPP–CeO 2 nanocomposites, the LOD for H2O2 is 0.0061 mM, lower than that of Co3O4 [69] and Fe3O4 nanoparticles [11] while higher than that of Fe3 O4 nanocomposite in MMS-40 [82] and carbon dots [10]. Moreover, LOD for glucose is 0.033 mM, higher than that of other nanostructures listed in Table 2. This results shows that LOD for H2O2 and glucose are different, due to the different kinds, different morphologies and different sizes of nanomaterials. Furthermore, the LOD for H2O2 and glucose are also concerned with the catalytic mechanism of both hydroxyl radicals and electron transfer. 4. Conclusions H2TCPP functionalized CeO2 nancomposites were synthesized by a facile method. The H2TCPP–CeO2 nancomposites had a higher enzyme activity toward H2O2-mediated TMB reaction than those of HRP and CeO2 nanostuctures. We have found that the catalytic activity of the H2TCPP–CeO2 nancomposites is dependent on temperature and pH. Table 2 LOD for H2O2 and glucose using different nanomaterials, respectively. Nanomaterials
LOD for H2O2 (mM)
LOD for glucose (mM)
H2TCPP–CeO2 [our work] Fe3O4 nanocomposite in MMS-40 [82] Co3O4 nanoparticles [69] Carbon dots [10] Fe3O4 nanoparticles [11]
0.0061 0.0005 0.01 0.0002 0.03
0.033 0.003 0.005 0.0004 0.003
References [1] G. Liu, Y. Wan, V. Gau, J. Zhang, L.H. Wang, S.P. Song, C.H. Fan, J. Am. Chem. Soc. 130 (2008) 6820–6825. [2] F. Wen, Y.H. Dong, L. Feng, S. Wang, S.C. Zhang, X.R. Zhang, Anal. Chem. 83 (2011) 1193–1196. [3] P. Wu, Y. He, H.F. Wang, X.P. Yan, Anal. Chem. 82 (2010) 1427–1433. [4] Q. Zhao, X.F. Li, X.C. Le, Anal. Chem. 83 (2011) 9234–9236. [5] E. Shoji, M.S. Freund, J. Am. Chem. Soc. 123 (2001) 3383–3384. [6] R. Breslow, Acc. Chem. Res. 28 (1995) 146–153. [7] (a) K. Tian, M. Prestgard, A. Tiwari, Mater. Sci. Eng. C 41 (2014) 100–118; (b) D.L. Nelson, M.M. Cox, Lehninger Principles of Biochemistry, 4th ed. Freeman, New York, 2005 (Chapter 6). [8] Y.J. Song, X.H. Wang, C. Zhao, K.G. Qu, J.S. Ren, X.G. Qu, Chem. Eur. J. 16 (2010) 3617. [9] L.Z. Gao, J. Zhuang, L. Nie, J.B. Zhang, Y. Zhang, N. Gu, T. Wang, J. Feng, D. Yang, S. Perrett, X. Yan, Nat. Nanotechnol. 2 (2007) 577–583. [10] W.B. Shi, Q.L. Wang, Y.J. Long, Z.L. Cheng, S.H. Chen, H.Z. Zheng, Y.M. Huang, Chem. Commun. 47 (2011) 6695. [11] H. Wei, E. Wang, Anal. Chem. 80 (2008) 2250–2254. [12] X.Q. Zhang, S.W. Gong, Y. Zhang, T. Yang, C.Y. Wang, N. Gu, J. Mater. Chem. 20 (2010) 5110–5116. [13] W. Shi, X. Zhang, S. He, Y. Huang, Chem. Commun. 47 (2011) 10785–10787. [14] F. Yu, Y. Huang, A.J. Cole, V.C. Yang, Biomaterials 30 (2009) 4716–4722. [15] X. Zuo, C. Peng, Q. Huang, S. Song, L. Wang, D. Li, C. Fan, Nano Res. 2 (2009) 617–623. [16] S. Liu, F. Lu, R. Xing, J.J. Zhu, Chem. Eur. J. 17 (2011) 620–625. [17] H. Niu, D. Zhang, S. Zhang, X. Zhang, Z. Meng, Y. Cai, J. Hazard. Mater. 190 (2011) 559–565. [18] S. He, W. Shi, X. Zhang, J. Li, Y. Huang, Talanta 82 (2010) 377–383. [19] K.S. Park, M.I. Kim, D.Y. Cho, H.G. Park, Small 7 (2011) 1521–1525. [20] N. Wang, L. Zhu, M. Wang, D. Wang, H. Tang, Ultrason. Sonochem. 214 (2009) 4–9. [21] C. Korsvik, S. Patil, S. Seal, W.T. Self, Chem. Commun. (2007) 1056–1058. [22] M. Catauro, F. Bollino, F. Papale, M. Gallicchio, S. Pacifico, Mater. Sci. Eng. C 48 (2015) 548–555. [23] (a) E.G. Heckert, A.S. Karakoti, S. Seal, W.T. Self, Biomaterials 29 (2008) 2705–2709; (b) A. Asati, S. Santra, C. Kaittanis, S. Nath, J.M. Perez, Angew. Chem. Int. Ed. 48 (2009) 2308–2312. [24] T. Pirmohamed, J.M. Dowding, S. Singh, B. Wasserman, E. Heckert, A.S. Karakoti, J.E.S. King, S. Seal, W.T. Self, Chem. Commun. 46 (2010) 2736–2738. [25] R. Andre, F. Natalio, M. Humanes, J. Leppin, K. Heinze, R. Wever, H.C. Schroder, W.E.G. Muller, W. Tremel, Adv. Funct. Mater. 21 (2011) 501–509. [26] W. He, X. Wu, J. Liu, X. Hu, K. Zhang, S. Hou, W. Zhou, S. Xie, Chem. Mater. 22 (2010) 2988–2994. [27] Y. Jv, B. Li, R. Cao, Chem. Commun. 46 (2010) 8017–8019. [28] J. Fan, J.J. Yin, B. Ning, X. Wu, Y. Hu, M. Ferrari, G.J. Anderson, J. Wei, Y. Zhao, G. Nie, Biomaterials 32 (2011) 1611–1618. [29] W. He, Y. Liu, J. Yuan, J.J. Yin, X. Wu, X. Hu, K. Zhang, J. Liu, C. Chen, Y. Ji, Y. Guo, Biomaterials 32 (2011) 1139–1147. [30] J. Liu, X. Hu, S. Hou, T. Wen, W. Liu, X. Zhu, X. Wu, Chem. Commun. 47 (2011) 10981–10983. [31] X.X. Wang, Q. Wu, Z. Shan, Q.M. Huang, Biosens. Bioelectron. 26 (2011) 3614–3619. [32] Y. Song, K. Qu, C. Zhao, J. Ren, X. Qu, Adv. Mater. 22 (2010) 2206–2210. [33] Y. Song, X. Wang, C. Zhao, K. Qu, J. Ren, X. Qu, Chem. Eur. J. 16 (2010) 3617–3621. [34] R. Cui, Z. Han, J.J. Zhu, Chem. Eur. J. 17 (2011) 9377–9384. [35] F. Qu, T. Li, M. Yang, Biosens. Bioelectron. 26 (2011) 3927–3931. [36] W. Shi, Q. Wang, Y. Long, Z. Cheng, S. Chen, H. Zheng, Y. Huang, Chem. Commun. 47 (2011) 6695–6697. [37] Y. Song, Y. Chen, L. Feng, X. Qu, Chem. Commun. 47 (2011) 4436–4438. [38] X. Wang, K. Qu, B. Xu, J. Ren, X. Qu, Nano Res. 4 (2011) 908–920. [39] Y. Song, W. Wei, X. Qu, Adv. Mater. 23 (2011) 4215–4236. [40] R. Lloyd, R.L. Jenkins, M. Piccinini, Q. He, C.J. Kiely, A.F. Carley, S.E. Golunski, D. Bethell, J.K. Bartley, G.J. Hutchings, J. Catal. 283 (2011) 161–167. [41] J.D. Qiu, S.G. Cui, R.P. Liang, Mikrochim. Acta 171 (2010) 333–339.
Q. Liu et al. / Materials Science and Engineering C 59 (2016) 445–453 [42] Y.S. Chaudhary, S. Panigrahi, S. Nayak, B. Satpati, S. Bhattacharjee, N. Kulkarni, J. Mater. Chem. 20 (2010) 2381–2385. [43] K. Yung Jun, K.O. Joong, K. Min Cheol, S. Myung Won, I. Young, K. Jae Jeong, J. Electrochem. Soc. 157 (2010) 952–958. [44] Y. Xuan, J. Hu, K. Xu, X. Hou, Y. Lv, Sensors Actuators B 136 (2009) 218–223. [45] L. Liao, H.X. Mai, Q. Yuan, H.B. Lu, J.C. Li, C. Liu, C.H. Yan, Z.X. Shen, T. Yu, J. Phys. Chem. C 112 (2008) 9061–9065. [46] P. Fornasiero, A. Speghini, R. Di Monte, M. Bettinelli, J. Kaspar, A. Bigotto, V. Sergo, M. Graziani, Chem. Mater. 16 (2004) 1938–1944. [47] J.P. Chen, S. Patil, S. Seal, J.F. McGinnis, Nat. Nanotechnol. 1 (2006) 142. [48] R.W. Tarnuzzer, J. Colon, S. Patil, S. Seal, Nano Lett. 5 (2005) 2573. [49] J. Niu, A. Azfer, L.M. Rogers, X. Wang, P.E. Kolattukudy, Cardiovasc. Res. 73 (2007) 549. [50] M. Das, S. Patil, N. Bhargava, J.F. Kang, L.M. Riedel, S. Seal, J.J. Hickman, Biomaterials 28 (2007) 1918. [51] X. Xiao, Q. Luan, X. Yao, K. Zhou, Biosens. Bioelectron. 24 (2009) 2447–2451. [52] D. Schubert, R. Dargusch, J. Raitano, S.W. Chan, Biochem. Biophys. Res. Commun. 342 (2006) 86–91. [53] A. Karakoti, S. Singh, J.M. Dowding, S. Sealand, W.T. Self, Chem. Soc. Rev. 39 (2010) 4422–4432. [54] T. Pirmohamed, J.M. Dowding, S. Singh, B. Wasserman, E. Heckert, A.S. Karakoti, J.E.S. King, S. Seal, W.T. Self, Chem. Commun. 46 (2010) 2736. [55] X. Xiao, Q. Luan, X. Yao, K. Zhou, Biosens. Bioelectron. 24 (2009) 2447–2451. [56] X. Jiao, H.J. Song, H.H. Zhao, W. Bai, L.C. Zhang, Anal. Methods 4 (2012) 3261. [57] K. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, Academic Press, New York, 1999. [58] A.D. Adler, F.R. Longo, J.D. Finarelli, J. Goldmacher, J. Assour, L. Korsakoff, J. Org. Chem. 32 (1967) 476. [59] B. Tang, L.H. Zhuo, J.C. Ge, G.L. Wang, Chem. Commun. (2005) 3565–3567. [60] Q. Wang, Y. Chen, P. Ma, J. Lu, X. Zhang, J. Jiang, J. Mater. Chem. 21 (2011) 8057–8065. [61] G. Lu, X. Zhang, X. Cai, J. Jiang, J. Mater. Chem. 19 (2009) 2417–2424. [62] A.W. Snow, in: K.M. Kadish, R. Smith (Eds.), The Porphyrin Handbook, Guilard, Elsevier Science 2003, p. 129. [63] M. Kasha, H.R. Rawls, M.A. El-Bayoumi, Pure Appl. Chem. 11 (1965) 371.
453
[64] P. Burroughs, A. Hamnett, A.F. Orchard, G. Thornton, J. Chem. Soc. Dalton Trans. (1976) 1686–1698. [65] B. Li, Y. Du, T. Li, S. Dong, Anal. Chim. Acta 651 (2009) 234–240. [66] K. Ishibashi, A. Fujishima, T. Watanabe, K. Hashimoto, J. Photochem. Photobiol. A 134 (2000) 139–142. [67] L. Su, J. Feng, X.M. Zhou, C.L. Ren, H.H. Li, X.G. Chen, Anal. Chem. 84 (2012) 5753–5758. [68] W.B. Shi, X.D. Zhang, S.H. He, Y.M. Huang, Chem. Commun. 47 (2011) 10785–10787. [69] (a) J.S. Mu, Y. Wang, M. Zhao, L. Zhang, Chem. Commun. 48 (2012) 2540–2542; (b) Q. Liu, Y. Yang, H. Li, R. Zhu, Q. Shao, S. Yang, J. Xu, Biosens. Bioelectron. 64 (2015) 147–153; (c) N. Wetchakun, S. Chaiwichain, B. Inceesungvorn, K. Pingmuang, S. Phanichphant, A.I. Minett, J. Chen, ACS Appl. Mater. Interfaces 4 (2012) 3718–3723; (d) J. Roh, S.H. Hwang, J. Jang, ACS Appl. Mater. Interfaces 6 (2014) 19825–19832; (e) W.W. Tu, J.P. Lei, P. Wang, H.X. Ju, Chem. Eur. J. 17 (2011) 9440–9447. [70] X. Xu, X. Yang, Anal. Methods 3 (2011) 1056–1059. [71] E.S. Forzani, H.Q. Zhang, L.A. Nagahara, I. Amlani, R. Tsui, N. Tao, Nano Lett. 4 (2004) 1785. [72] R. Gill, L. Bahshi, R. Freeman, I. Willner, Angew. Chem. Int. Ed. 47 (2008) 1676. [73] H. Wei, E. Wang, Anal. Chem. 80 (2008) 2250. [74] V. Sanz, S. de Marcos, J.R. Castillo, J. Galban, J. Am. Chem. Soc. 127 (2005) 1038. [75] R. Kurita, H. Tabei, Y. Iwasaki, K. Hayashi, K. Sunagawa, O. Niwa, Biosens. Bioelectron. 20 (2004) 518. [76] P.F. Pang, Y.L. Zhang, S.T. Ge, Q.Y. Cai, S.Z. Yao, C.A. Grimes, Sensors Actuators B Chem. 136 (2009) 310. [77] H.S.M. Abd-Rabboh, M.E. Meyerhoff, Talanta 72 (2007) 1129. [78] S. Cosnier, F. Lambert, M. Stoytcheva, Electroanalysis 12 (2000) 356. [79] K. Abe, K. Suzuki, D. Citterio, Anal. Chem. 80 (2008) 6928. [80] Y.X. Li, X.Q. Lin, Sensors Actuators B 115 (2006) 134–139. [81] J. Wang, Electroanalysis 17 (2005) 7–14. [82] M. Kim, J. Shim, T. Li, J. Lee, H.G. Park, Chem. Eur. J. 17 (2011) 10700–10707.