Two birds one stone: Facile preparation of AIE-active fluorescent polymeric nanoparticles via self-catalyzed photo-mediated polymerization

Journal Pre-proofs Full Length Article Two birds one stone: facile preparation of AIE-active fluorescent polymeric nanoparticles via self-catalyzed photo-mediated polymerization Jiande Dong, Ruming Jiang, Weimin Wan, Haijun Ma Wan, Hongye Huang Wan, Yulin Feng Wan, Yanfeng Dai Wan, Hui Ouyang, Xiaoyong Zhang, Yen Wei PII: DOI: Reference:

S0169-4332(19)33615-3 https://doi.org/10.1016/j.apsusc.2019.144799 APSUSC 144799

To appear in:

Applied Surface Science

Received Date: Revised Date: Accepted Date:

3 September 2019 7 November 2019 19 November 2019

Please cite this article as: J. Dong, R. Jiang, W. Wan, H. Ma Wan, H. Huang Wan, Y. Feng Wan, Y. Dai Wan, H. Ouyang, X. Zhang, Y. Wei, Two birds one stone: facile preparation of AIE-active fluorescent polymeric nanoparticles via self-catalyzed photo-mediated polymerization, Applied Surface Science (2019), doi: https:// doi.org/10.1016/j.apsusc.2019.144799

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

© 2019 Published by Elsevier B.V.

Two birds one stone: facile preparation of AIE-active fluorescent polymeric nanoparticles via selfcatalyzed photo-mediated polymerization Jiande Donga,#, Ruming Jianga,#, Weimin Wana,b, Haijun Mac, Hongye Huanga, Yulin Fengb, Yanfeng Daia, Hui Ouyangb,*, Xiaoyong Zhanga,*, Yen Weic,d,* a

Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031, China.

b

Jiangxi University of Traditional Chinese Medicine, 56 Yangming Road, Jiangxi, Nanchang, 330006,

China c Department

of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University,

Beijing, 100084, P. R. China. d

Department of Chemistry and Center for Nanotechnology and Institute of Biomedical Technology,

Chung-Yuan Christian University, Chung-Li 32023, Taiwan # These authors contributed equally to this work. * Corresponding authors Hui Ouyang [email protected] Xiaoyong Zhang [email protected] Yen Wei [email protected]

Abstract In this work, we report the first preparation of AIE-active FPNs via metal-free photo-mediated atom transfer radical polymerization (ATRP), employing 2-methacryloyloxyethyl phosphorylcholine (MPC) and benzyl methacrylate (BzMA) as the monomers. Herein, the AIE fluorogen, 10-phenylphenothiazine (PTH)-containing α-bromoester (named as PTH-Br), was simultaneously used as the initiator and photocatalyst. We found that the AIE-active PTH-P(BzMA-MPC)-20(40) FPNs in water can emit intense fluorescence, with high fluorescence quantum yields of 34.3% and 41.2%, respectively, and show excellent water dispersibility and a low critical micelle concentration (CMC). To explore their potential for biomedical applications, biocompatibility evaluation and the cell uptake behavior of these FPNs were further studied. The results demonstrated that these polymeric nanoparticles are biocompatible with L02 cells and are promising for bioimaging applications. Compared with the traditional strategies for preparing AIE-active FPNs, the method described in this work can occur at room temperature, does not require metal catalysts, and is highly efficient. This work lays the foundation for the fabrication of AIEactive functional materials and broadens the potential of AIE-active molecules.

Keywords: Fluorescent polymeric nanoparticles, aggregation-induced emission, self-catalyzed atom transfer radical polymerization, metal-free photo-mediated polymerization 1 Introduction

Organic light-emitting materials, including organic small molecule materials, polymers and metal chelates, have received increasing research attention because they are adjustable, colorful, designable, and are available in a wide variety.[1-9] Organic small molecule materials have been widely used in various applications, such as in DNA diagnosis, photochemical sensors, dyes, organic light-emitting devices (OLEDs), as well as in bioimaging.[10-16] However, for various biomedical applications, there are some inherent shortcomings in their practical use. Metal chelates synthesized from rare earth metals and organic components have a high fluorescence quantum efficiency of the organic component and also possess good stability of the inorganics; however, their high cytotoxicity and low biocompatibility derived from the possible release of cytotoxic heavy metals is unfavorable for biomedical applications.[17-21] Conventional organic small molecules can emit light efficiently when dissolved in appropriate solvents, but they can aggregate due to a strong π-π stacking effect, resulting in fluorescence weakening or even quenching.[22-24] This phenomenon is called aggregation-caused quenching (ACQ) and limits the applications of luminescent organic materials in practical production and scientific research to a large extent.[25, 26] Recently, organic dyes with aggregation-induced emission (AIE) have emerged as popular candidates for fluorescent polymeric nanoparticle (FPN) fabrication.[27-35] The AIE-active dyes show greatly enhanced fluorescence in the aggregated state due to the restricted intramolecular motion, which can effectively eliminate the ACQ problem.[36-40] Thus, FPNs based on AIE dyes can offer very bright fluorescence and high water dispersibility, which are very important for long-term biological applications. In recent years, our group has also designed and synthesized a series of AIE-active FPNs using interesting fabrication methods, such as emulsion polymerization, ringopening polymerization, and reversible addition fragmentation chain transfer (RAFT) polymerization.[5, 41-48] Nonetheless, some fabrication methods require a high temperature, involve complicated processes and need metal catalysts. Therefore, there is abundant room for improvement in the fabrication of FPNs with AIE characteristics via a simple procedure. Atom transfer radical polymerization (ATRP) represents one of the most efficient polymerization techniques and has become a powerful tool for preparing functional polymers over the past two decades.[49, 50] The transition metal catalyst [e.g., Cu(I), Fe(II), Ru(II)] is the most important component of ATRP and has a key role in establishing the redox equilibrium of a reactive species and a dormant species in all ATRP processes to obtain polymers with low polydispersity via homogeneous chain growth.[51-53] Unfortunately, these metal catalysts are difficult to purify and to maintain within a

polymer, limiting their application potential, especially in microelectronics and biomaterials.[54, 55] Furthermore, many organic fluorophores coordinated with metal catalysts cause fluorescence quenching.[56] Significantly, in 2014, the Hawker group first described the metal-free photo-mediated ATRP of methacrylate using 10-phenylphenothiazine (PTH) as an organic photocatalyst under 380 nm (200 mW) light-emitting diode (LED) irradiation at room temperature.[57, 58] This novel and ecofriendly metal-free ATRP can overcome the challenge of metal contamination in polymers in traditional ATRP systems.[58] Hence, we envisaged the development of a photo-mediated ATRP strategy for the fabrication of AIE-active FPNs. In this study, we designed and synthesized a PTH-based photo-initiator AIE dye (PTH-Br; the structure is shown in Scheme1) for the preparation of biocompatible AIE-active FPNs through in situ metal-free photo-mediated ATRP. The PTH-Br synthesized in this work is not only a hydrophobic AIE dye and fluorophore, it can also act as an initiator and photocatalyst for photo-mediated ATRP. As shown in Scheme 1, the photo-mediated ATRP of benzyl methacrylate (BzMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) was accomplished by using the photo-initiator AIE dye PTH-Br under 380 nm LED irradiation at room temperature. Two different fluorescent copolymers, PTH-P(BzMA-MPC)20(40), were prepared by changing the monomer contents of BzMA and MPC. Due to their amphipathic nature, the copolymers of PTH-P(BzMA-MPC) can self-assemble into stable AIE-active FPNs with excellent dispersibility in physiological solution. To assess how the final polymeric nanomaterials perform in a biological application, the biocompatibility and cell uptake behavior of the PTH-P(BzMAMPC) FPNs were evaluated using bioimaging.

Self-assembly

PTH-P(BzMA-MPC)

Cell imaging

PTH-P(BzMA-MPC) FPNs

Scheme 1 Schematic showing the preparation of luminescent PTH-P(BzMA-MPC) copolymers and their

self-assembly into FPNs in aqueous solution. The resulting AIE-active FPNs were further used for cell imaging.

2 Experimental 2.1 Materials and characterization Benzyl methacrylate (BzMA, MW: 176.21 Da, 98%), triethylamine (TEA, MW: 101.19 Da, 99.0%), αbromoisobutyryl bromide (MW: 229.90 Da, 98%) and anhydrous N,N-dimethylformamide (DMF, MW: 73.09 Da, 99.8%) were obtained from Aladdin (Shanghai, China) and used as received. 2Methacryloyloxyethyl phosphorylcholine (MPC, MW: 295.27 Da, 96%) was purchased from Heowns Biochem Technologies (Tianjin, China). All other commercially available reagents were used without further

purification.

The

intermediate

2-(4-aminophenyl)-3-(10-phenyl-10H-phenothiazin-3-

yl)acrylonitrile (PTH-NH2) was synthesized and characterized in our previous work.[59] 1H nuclear magnetic resonance (NMR) spectra were obtained with a Bruker Avance-400 spectrometer [tetramethylsilane (TMS) as the internal standard]. Mass spectra (MS) were recorded with a MALDITOF MS (Shimadzu, Japan). The Fourier transform infrared spectroscopy (FT-IR) spectra were measured on a Nicolet5700 (Thermo Nicolet Corporation) in transmission mode using KBr pellets. The fluorescence spectra were determined by using a fluorescence spectrophotometer (FSP, model: C1136711) with a slit width of 3 nm for both excitation and emission. The UV-visible absorption spectra of the nanoparticles were acquired with a Perkin Elmer LAMBDA 35 UV/Vis system using quartz cuvettes with a 1 cm path length. Transmission electron microscopy (TEM) images were recorded on a Hitachi 7650B microscope operating at 80 kV. The size distribution of PTH-P(BzMA-MPC) FPNs in water was determined by a Zeta Plus apparatus (Zeta Plus, Brookhaven Instruments, Holtsville, NY). X-ray photoelectron spectra (XPS) were recorded on a PHI Model Quantera SXM scanning X-ray microprobe using Al Kα as the excitation source (1486.6 eV), with binding energy calibration based on C 1s at 284.6 eV. Gel permeation chromatography (GPC) was recorded from a Shimadzu LC-20AD pump system, which was performed using N,N-dimethylformamide (DMF) containing 50 mM LiBr as the eluent. 2.2 Synthesis of PTH-Br The multifunctional AIE dye PTH-Br was synthesized by a simple acylation reaction. Briefly, αbromoisobutyryl bromide (0.69 g, 3 mmol) was added dropwise to a solution of PTH-NH2 (1.04 g, 2.5 mmol) in anhydrous DMF (20 mL) at 0 °C and incubated for 30 min. Subsequently, TEA (0.42 mL, 3

mmol) was slowly added and then stirred overnight at room temperature. The crude product was purified by silica gel column chromatography using ethyl acetate/petroleum ether (1/20) as the eluent to yield pure PTH-Br (1.2 g, 85% yield). MS: m/z = 565.625 0. 1H NMR (400 MHz, CD3CN), δ (ppm): 9.54 (s, 1H), 7.73-7.27 (m, 12H), 7.06-6.70 (m, 4H), 1.99 (s, 6H). 2.3 Preparation of PTH-P(BzMA-MPC) The PTH-P(BzMA-MPC) copolymers were prepared through the metal-free photo-mediated ATRP method using MPC and BzMA as the monomers. The preparation route is shown in Scheme 1 and described as follows: MPC (295 mg, 1 mmol) and BzMA (88 mg, 0.5 mmol) were charged into a dry Schlenk tube along with ethanol (EtOH, 3 mL). PTH-Br (14 mg, 0.025 mmol) dissolved in DMF (3 mL) was then added into the Schlenk tube and purged by nitrogen flow for 30 min. The reaction was vigorously stirred in front of 380 nm LEDs at room temperature for 8 h. The mixture solution was dialyzed against tap water for 48 h and ethanol for 12 h using a dialysis bag (MWCO 3500 Da). The product was lyophilized in a vacuum freeze dryer to obtain PTH-P(BzMA-MPC)-20 copolymers (261mg ,68% yield). For synthesis of PTH-P(BzMA-MPC)-40, the amount of BzMA was changed to 176 mg (339mg,72% yield). 2.4 Cell viability and cell uptake experiments To evaluate the potential use of these PTH-P(BzMA-MPC) FPNs in biomedical fields, the cell viability and cell uptake behavior of PTH-P(BzMA-MPC) FPNs were determined by CCK-8 assay and confocal laser scanning microscopy (CLSM) observation. Detailed experimental procedures are provided in the supporting information. 3 Results and discussion 3.1 Characterization of PTH-P(BzMA-MPC) FPNs Metal-free ATRP of BzMA and MPC was performed in a mixed solvent of DMF/EtOH in the presence of the AIE dye PTH-Br as photocatalyst and initiator (Scheme 1). The ratio of PTH-Br/MPC/BzMA was 1/40/20 to afford PTH-P(BzMA-MPC)-20, while the ratio of PTH-Br/MPC/BzMA was 1/40/40 to yield PTH-P(BzMA-MPC)-40. After the photopolymerization, the resulting amphiphilic fluorescent copolymers, PTH-P(BzMA-MPC), were fully characterized by a series of techniques. As shown in Fig. 1, the 1H NMR spectra of MPC and PTH-P(BzMA-MPC) are provided for comparison. The MPC and BzMA monomers both have two peaks, located at 6.11 and 5.62 ppm, which should be assigned to the chemical shifts of the protons connected with the C=C bond (Fig. 1A and Fig. S1).[60] After photo-

initiating the polymerization of MPC and BzMA, some characteristic chemical shift stemming from BzMA and MPC could be observed in the 1H NMR spectrum of PTH-P(BzMA-MPC). For example, the characteristic chemical shift of MPC located between 3 to 5 ppm is found in the sample of PTH-P(BzMAMPC). More importantly, the peaks of the protons connected with the C=C bond of the monomers disappeared, while a new signal peak appeared at 7.32 ppm, which can be attributed to the protons of aromatic rings owing to the introduction of BzMA and PTH-Br. Moreover, a signal peak was clearly observed in the 31P NMR spectra of MPC monomer and of PTH-P(BzMA-MPC) (Fig. S2-4). Therefore, the successful metal-free photo-mediated ATRP of MPC and BzMA is confirmed according to the NMR spectra.

Fig. 1 1H NMR spectra of MPC (A), PTH-P(BzMA-MPC)-20 (B) and PTH-P(BzMA-MPC)-40 (C) in CD3OD.

In addition to the NMR spectra, the FT-IR spectra were also utilized to confirm the successful preparation of PTH-P(BzMA-MPC). As shown in Fig. 2, two characteristic peaks, at 1716 and 1638 cm-1, were observed in the spectra of MPC and BzMA that could be attributed to the stretching vibration of C=O and C=C bonds, respectively. Two characteristic peaks located at 1256 and 1176 cm-1 are assigned to the stretching vibration of P=O and the P-O bond of MPC, and some sharp peaks at 16101480 cm-1 can be ascribed to the C-H stretching vibration of the aromatic ring of BzMA. After photomediated ATRP, many vibration peaks, such as C=O, P=O, P-O and C-H of aromatic rings, still existed in the sample of PTH-P(BzMA-MPC)-20(40). Notably, the stretching vibration of the monomer C=C

bond disappeared, confirming that PTH-P(BzMA-MPC) was successful prepared. In the other hand, the average weight of the PTH-P(BzMA-MPC) was record by the GPC. Shown in the Fig. S11 and Fig. S12, The Mw of the PTH-P(BzMA-MPC)-20 and PTH-P(BzMA-MPC)-40 is 59039 g/mol and 63095g/mol respectively. The PDI is 1.52 and 1.48, respectively.

Fig. 2 FT-IR spectra of BzMA (A), MPC (B), PTH-P(BzMA-MPC)-20 (C) and PTH-P(BzMA-MPC)40 (D).

Moreover, the XPS results of PTH-P(BzMA-MPC) further showed that C and O were the major components, along with the existence of N, S, P and Br as minor components (Fig. 3A and Fig. 3B). The elements N and S can be ascribed to the successful introduction of PTH-NH2 into the copolymers. Moreover, the appearance of N and P in the XPS spectra could be evidence for the successful copolymerization of MPC and BzMA in the copolymers (Fig. S5 and Fig. S6). Furthermore, we also found that Br had almost disappeared in the copolymers, which further suggests the successful ATRP process via the self-catalyzed photo-mediated polymerization. Taken together, these results demonstrate the successful preparation of PTH-P(BzMA-MPC)-20(40) copolymers. The amphiphilic PTH-P(BzMAMPC) copolymers could self-assemble into water-dispersed PTH-P(BzMA-MPC) FPNs in aqueous solution, which were examined by dynamic light scattering (DLS) and TEM imaging. As shown in Fig. 3C and Fig. 3D, the DLS results showed that the effective diameters of the PTH-P(BzMA-MPC)-20 FPNs and PTH-P(BzMA-MPC)-40 FPNs in water were 146.1 and 76.7 nm, respectively. In the TEM images, many monodispersed spherical nanoparticles with diameters tens of nanometers in size could be

observed, which directly demonstrated the successful self-assembly of the amphiphilic luminescent copolymers. The size obtained from the TEM characterization was relatively small compared to the size distribution of the DLS characterization, which may be due to micelle shrinkage during the drying process. The obvious different size distribution of these AIE-active FPNs with different chemical compositions is possibly ascribed to the different hydrophobic and hydrophilic ratios of these fluorescent copolymers. In this work, we found that the size of PTH-P(BzMA-MPC)-20 FPNs is obviously larger than that of PTH-P(BzMA-MPC)-40 FPNs. The above results indicated that adjustment of the feed ratios of hydrophobic monomers and hydrophilic monomers could influence the self-assembly behavior of these fluorescent copolymers. With the increase of hydrophilic monomers, the size of final selfassemblies will become smaller. Therefore, this work provides a facile route to adjust the final properties of AIE-active FPNs. It should be of great important for preparation of desirable AIE-active fluorescent probes and investigation the biomedical applications of AIE-active FPNs.

Fig. 3 (A) XPS spectrum of PTH-P(BzMA-MPC)-20 copolymer. Inset shows the content of C, N, O, S, P and Br in the PTH-P(BzMA-MPC)-20 copolymer. (B) XPS spectrum of PTH-P(BzMA-MPC)-40 copolymer. Inset shows the content of C, N, O, S, P and Br in PTH-P(BzMA-MPC)-40 copolymer. (C) DLS results of PTH-P(BzMA-MPC)-20 FPNs in water showing that the effective diameter of the nanoparticles was 146.1 nm, with a polydispersity index of 0.213. Inset is the TEM image of PTHP(BzMA-MPC)-20 FPNs dispersed in aqueous solution. (D) DLS results of PTH-P(BzMA-MPC)-40 FPNs in water showing that the effective diameter of the nanoparticles was 76.7 nm, with a polydispersity

index of 0.210. Inset is the TEM image of PTH-P(BzMA-MPC)-40 FPNs dispersed in aqueous solution.

The AIE property of PTH-Br was studied in a THF/water mixture with different water fractions (fw). As illustrated in Fig. 4A and Fig. 4B, when the fw increased from 0 to 60%, the emission intensity of PTH-Br gradually decreased, possibly due to the enhancement of the twisted intramolecular charge transfer (TICT) effect caused by an increase in solvent polarity.[61] Subsequently, the intensity was abruptly enhanced with a concomitant blueshift due to aggregate formation, indicating the distinct AIE property of PTH-Br.[62] To better understand the structure and electronic properties of PTH-Br, density functional theory (DFT) calculations were carried out using Gaussian 09 at B3LYP/6-31G(d) level of theory. Figure 4C shows the DFT-optimized molecular geometry of PTH-Br. As shown in Fig. 4D, the highest occupied molecular orbital (HOMO) is located mainly on the 10-phenylphenothiazine unit, while the lowest unoccupied molecular orbital (LUMO) is localized on the nitrile group. The electron density transfers reveal its intrinsic TICT effect. The unique AIE property makes PTH-Br a suitable candidate for preparing ultra-bright FPNs for biomedical applications.

Fig. 4 (A) Photoluminescence spectra of PTH-Br in THF/water mixtures with various water fractions, and (B) plot of relative peak intensity (I/I0) and emission wavelength of PTH-Br versus fw in the mixture. I0 was the PL intensity at 60% fw when the excitation wavelength (λex) = 431 nm. (C) Optimized molecular geometry of PTH-Br. (D) Calculated molecular orbitals for PTH-Br using B3LYP with 6-31G

(d) basis.

PTH-P(BzMA-MPC) FPNs displayed ultra-high water dispersibility due to the self-assembly of amphiphilic copolymers. Figure 5 shows the UV-vis and PL spectra of the PTH-P(BzMA-MPC) FPNs dispersed in water. It can be observed that the AIE-active PTH-P(BzMA-MPC) FPNs have two main absorption peaks in their spectra. Two absorption peaks are centered at 339 and 422 nm in the PTHP(BzMA-MPC)-20 FPN sample, while two absorption peaks are located at 338 and 414 nm in the PTHP(BzMA-MPC)-40 FPNs (Fig. 5A). The absorption spectra began to increase from 800 nm, indicating the presence of PTH-P(BzMA-MPC) FPNs in solution caused by the Mie effect. Additionally, the PTHP(BzMA-MPC) FPN suspension showed great dispersibility in water, and no precipitation was observed after one week of storage. Due to the aggregation of AIE fluorogen in the core of the nanoparticles, the PTH-P(BzMA-MPC) FPNs emitted strong fluorescence when dispersed in water and irradiated with a UV lamp at 365 nm (inset of Fig. 5B). The AIE-active PTH-P(BzMA-MPC)-20 FPNs showed an emission maximum located at 568 nm, and the maximum excitation peak appeared at 437 nm. For the PTH-P(BzMA-MPC)-40 FPNs, the maximum emission peak was located at 552 nm when excited at 431 nm. The optical difference between the PTH-P(BzMA-MPC)-20 and PTH-P(BzMA-MPC)-40 samples could be because of the different ratios of hydrophilic and hydrophobic segments.[63] The redshift of the fluorescence emission wavelength in PTH-P(BzMA-MPC)-20 could be ascribed to the tighter aggregation of dye in the FPN core. The fluorescence quantum yields of the PTH-P(BzMA-MPC)-20 FPNs (1 mg/mL-1) and PTH-P(BzMA-MPC)-40 FPNs (1 mg/mL-1) in water were 34.3% and 41.2%, respectively, measured using Rhodamine B (1 mg/mL-1) in ethanol as the standard (quantum yield = 89%). Photostability is a key evaluation factor of fluorescent materials. The PL spectra of the PTHP(BzMA-MPC)-20(40) FPN suspensions irradiated with a UV lamp at 365 nm for different times are shown in Fig. 5C and Fig. 5D. The emission intensities of the PTH-P(BzMA-MPC)-20(40) FPNs were slightly decreased. The results indicated that the PTH-P(BzMA-MPC)-20(40) FPNs possess excellent fluorescence stability, which is important for their use in biomedical research applications. The critical micelle concentration (CMC) of the PTH-P(BzMA-MPC) FPNs was measured by a previous method.[64] The PL intensities at the maximum emission wavelength versus the logarithm of the corresponding PTHP(BzMA-MPC) concentration are plotted in Fig. S7 and Fig. S8. The CMCs of the PTH-P(BzMA-MPC)20 FPNs and PTH-P(BzMA-MPC)-40 FPNs in water were 11.5 and 11.9 μg/mL, respectively.

Fig. 5 Spectroscopy characterization of PTH-P(BzMA-MPC) FPNs. (A) UV-Vis spectra. Inset: visible image of PTH-P(BzMA-MPC)-20 FPNs (left cuvette) and PTH-P(BzMA-MPC)-40 FPNs (right cuvette) in water. (B) PL spectra of PTH-P(BzMA-MPC) FPNs. Inset: fluorescence image of PTH-P(BzMAMPC)-20 FPNs (left cuvette) and PTH-P(BzMA-MPC)-40 FPNs (right cuvette) in water. (C) Photostability of PTH-P(BzMA-MPC)-20 FPNs in water, λex = 437 nm. (D) Photostability of PTHP(BzMA-MPC)-40 FPNs in water, λex = 431 nm.

3.2 Biocompatibility of PTH-P(BzMA-MPC) FPNs To explore the potential of the PTH-P(BzMA-MPC) FPNs to be used in biomedical applications, their biocompatibility was evaluated through determining the cell viability of PTH-P(BzMA-MPC) FPNs on L02 cells tested by CCK-8. The effect of the PTH-P(BzMA-MPC)-20 FPNs on the survival of L02 cells was evaluated through measuring cell viability after incubation with different concentrations of PTHP(BzMA-MPC)-20 FPNs for 24 hours. As shown in Fig. 6, no significant decrease of cell viability was observed for those incubated with 10-320 µg mL-1 PTH-P(BzMA-MPC)-20 FPNs. Notably, when the cells were incubated with 320 µg mL-1 PTH-P(BzMA-MPC)-20 FPNs for 24 h, the cell viability is still greater than 90%, suggesting the excellent biocompatibility of PTH-P(BzMA-MPC)-20 FPNs. The PTHP(BzMA-MPC)-40 FPNs also showed excellent biocompatibility (Fig. S9). MPC is a commonly used monomer for the surface construction and functionalization of materials. Thus, PTH-P(BzMA-MPC) FPNs have good application prospects for use in drug delivery and sustained release studies due to the presence of MPC. Based on the above findings, PTH-P(BzMA-MPC) FPNs prepared by photo-induced

ATRP possess excellent biocompatibility and satisfactory fluorescence properties, making them promising materials for use in cell imaging.

Fig. 6 Cell viability of L02 cells incubated for 24 h with PTH-P(BzMA-MPC)-20 FPNs at different concentrations (0–320 µg mL-1). The cell evaluation experiments suggested that the FPNs showed no toxicity toward cells.

3.3 Bioimaging application of PTH-P(BzMA-MPC) FPNs In view of the results of the above investigation, indicating that the PTH-P(BzMA-MPC) FPNs have excellent water dispersibility, stable fluorescence properties and favorable biocompatibility, the cellular uptake behavior and cell imaging observation of PTH-P(BzMA-MPC) FPNs was evaluated by CLSM, which was used to further explore their potential for application in biomedical research. As shown in Fig. 7A, when cells were incubated with 40 µg mL-1 PTH-P(BzMA-MPC)-20 FPNs for 30 min, strong fluorescence appeared in the L02 cells and was clearly observed in the CLSM images. In addition, there were many areas of weak or no fluorescence in the cells, which should be the location of the nucleus. PTH-P(BzMA-MPC)-20 FPNs cannot enter the nucleus, likely due to their particle size being larger than the nuclear pores. Therefore, the nanoparticles were taken up by cellular endocytosis and were distributed in the cytoplasm. The cells maintained their normal growth morphology, and the concentration of PTHP(BzMA-MPC)-20 FPNs used in the cell imaging studies was much less than the maximum concentration that showed excellent cell compatibility in the cell viability assays. Upon prolongation of the incubation time, the fluorescence signals increased (Fig. 7B). The CLSM images of PTH-P(BzMA-

MPC)-40 FPNs are shown in Fig. S10. Similar results were obtained. These findings indicate that PTHP(BzMA-MPC)-20 FPNs are suitable for cell imaging and biological tracing. 30 min

3h

A

B

C

D

Fig. 7 CLSM images of L02 cells incubated with PTH-P(BzMA-MPC)-20 FPNs (40 μg mL-1) for 30 min (A) excited with 405 nm and (C) bright field. L02 cells incubated for 3 h (B) excited with 405 nm and (D) bright field. Scale bar = 20 μm.

4 Conclusions In summary, we successfully fabricated biocompatible PTH-P(BzMA-MPC) FPNs with AIE features through self-catalyzed polymerization and demonstrated their applications for in vitro biological imaging. Such AIE-active PTH-P(BzMA-MPC) FPNs can be obtained via the self-assembly of amphiphilic PTHP(BzMA-MPC) copolymers, where PTH-P(BzMA-MPC) copolymers are prepared through the metalfree photo-mediated ATRP of MPC and BzMA monomers using the photo-initiated AIE dye PTH-Br under 380 nm LED irradiation at room temperature. The PTH-Br synthesized in this study is a hydrophobic AIE dye used as fluorophore, as well as an initiator and photocatalyst agent for photomediated ATRP. Benefitting from the AIE feature of PTH-Br, the AIE-active PTH-P(BzMA-MPC) FPNs show intense and stable fluorescence with high fluorescence quantum yield. These nanoparticles can be well dispersed in aqueous solution and exhibit excellent water dispersibility and a low CMC. In vitro cellular imaging revealed the ease of endocytosis of PTH-P(BzMA-MPC) FPNs in L02 cells. The

combination of the intense fluorescence, high photostability and water dispersibility and excellent biocompatibility indicates that PTH-P(BzMA-MPC) FPNs have broad biological application prospects. More importantly, we also found that the size distribution and fluorescent properties could be influenced by the hydrophobic and hydrophilic ratios of these AIE-active copolymers. This provides a facile and general route for fabrication of the AIE-active FPNs with desirable properties and functions. However, more detailed information about the relationship between size distribution (fluorescent properties) of AIE-active copolymers and their hydrophobic/hydrophilic ratios should be investigated in depth. Further studies based on this work will perform in our lab in future. Acknowledgments This research was supported by the National Natural Science Foundation of China (Nos. 21788102, 21865016, 51363016, 21474057, 21564006, 21561022, 21644014). References [1] K.T. Kamtekar, A.P. Monkman, M.R. Bryce, Recent advances in white organic light ‐ emitting materials and devices (WOLEDs), Advanced Materials, 22 (2010) 572-582. [2] Z. Wang, C. Xu, Y. Lu, G. Wei, G. Ye, T. Sun, J. Chen, Microplasma electrochemistry controlled rapid preparation of fluorescent polydopamine nanoparticles and their application in uranium detection, Chem. Eng. J., 344 (2018) 480-486. [3] L. Wang, W. Li, B. Wu, Z. Li, D. Pan, M. Wu, Room-temperature synthesis of graphene quantum dots via electron-beam irradiation and their application in cell imaging, Chem. Eng. J., 309 (2017) 374-380. [4] A. Mishra, P. Bäuerle, Small molecule organic semiconductors on the move: promises for future solar energy technology, Angewandte Chemie International Edition, 51 (2012) 2020-2067. [5] X. Zhang, K. Wang, M. Liu, X. Zhang, L. Tao, Y. Chen, Y. Wei, Polymeric AIE-based nanoprobes for biomedical applications: recent advances and perspectives, Nanoscale, 7 (2015) 11486-11508. [6] M. Zheng, H. Tan, Z. Xie, L. Zhang, X. Jing, Z. Sun, Fast response and high sensitivity europium metal organic framework fluorescent probe with chelating terpyridine sites for Fe3+, ACS Appl. Mater. Inter., 5 (2013) 1078-1083. [7] D. Ding, C.C. Goh, G. Feng, Z. Zhao, J. Liu, R. Liu, N. Tomczak, J. Geng, B.Z. Tang, L.G. Ng, Ultrabright Organic Dots with Aggregation-Induced Emission Characteristics for Real-Time Two-Photon Intravital Vasculature Imaging, Adv. Mater., 25 (2013) 6083-6088. [8] J. Mei, Y. Hong, J.W. Lam, A. Qin, Y. Tang, B.Z. Tang, Aggregation‐Induced Emission: The Whole Is More Brilliant than the Parts, Adv. Mater., 26 (2014) 5429-5479. [9] J. Mei, N.L. Leung, R.T. Kwok, J.W. Lam, B.Z. Tang, Aggregation-induced emission: together we shine, united we soar!, Chem. Rev., 115 (2015) 11718-11940. [10] Y. Cao, S. Zhu, J. Yu, X. Zhu, Y. Yin, G. Li, Protein detection based on small molecule-linked DNA, Anal. Chem., 84 (2012) 4314-4320. [11] J. Chan, S.C. Dodani, C.J. Chang, Reaction-based small-molecule fluorescent probes for chemoselective bioimaging, Nat. Chem., 4 (2012) 973. [12] O.A. Bozdemir, R. Guliyev, O. Buyukcakir, S. Selcuk, S. Kolemen, G. Gulseren, T. Nalbantoglu, H.

Boyaci, E.U. Akkaya, Selective manipulation of ICT and PET processes in styryl-bodipy derivatives: applications in molecular logic and fluorescence sensing of metal ions, J. Am. Chem. Soc., 132 (2010) 8029-8036. [13] D.H. Lee, M.J. Lee, H.M. Song, B.J. Song, K.D. Seo, M. Pastore, C. Anselmi, S. Fantacci, F. De Angelis, M.K. Nazeeruddin, Organic dyes incorporating low-band-gap chromophores based on π-extended benzothiadiazole for dye-sensitized solar cells, Dyes Pigments, 91 (2011) 192-198. [14] C. Sekine, Y. Tsubata, T. Yamada, M. Kitano, S. Doi, Recent progress of high performance polymer OLED and OPV materials for organic printed electronics, Sci. Technol. Adv. Mat., 15 (2014) 034203. [15] M. Zhang, W. Wang, P. Yuan, C. Chi, J. Zhang, N. Zhou, Synthesis of lanthanum doped carbon dots for detection of mercury ion, multi-color imaging of cells and tissue, and bacteriostasis, Chem. Eng. J., 330 (2017) 1137-1147. [16] J. Chen, M. Liu, Q. Huang, L. Huang, H. Huang, F. Deng, Y. Wen, J. Tian, X. Zhang, Y. Wei, Facile preparation of fluorescent nanodiamond-based polymer composites through a metal-free photoinitiated RAFT process and their cellular imaging, Chem. Eng. J., 337 (2018) 82-90. [17] M.P. Cuajungco, G.J. Lees, Diverse effects of metal chelating agents on the neuronal cytotoxicity of zinc in the hippocampus, Brain Res., 799 (1998) 97-107. [18] Y. Yang, F. An, Z. Liu, X. Zhang, M. Zhou, W. Li, X. Hao, C.S. Lee, X. Zhang, Ultrabright and ultrastable near-infrared dye nanoparticles for in vitro and in vivo bioimaging, Biomaterials, 33 (2012) 7803-7809. [19] H. Ouyang, M. Zhou, Y. Guo, M. He, H. Huang, X. Ye, Y. Feng, X. Zhou, S. Yang, Metabolites profiling of Pulsatilla saponin D in rat by ultra performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS/MS), Fitoterapia, 96 (2014) 152-158. [20] X. Zhang, J. Li, B. Xie, B. Wu, S. Lei, Y. Yao, M. He, H. Ouyang, Y. Feng, W. Xu, S. Yang, Comparative Metabolomics Analysis of Cervicitis in Human Patients and a Phenol Mucilage-Induced Rat Model Using Liquid Chromatography Tandem Mass Spectrometry, Front. Pharmacol., 9 (2018). [21] X. Zhang, M. He, S. Lei, B. Wu, T. Tan, H. Ouyang, W. Xu, Y. Feng, An integrative investigation of the therapeutic mechanism of Ainsliaea fragrans Champ. in cervicitis using liquid chromatography tandem mass spectrometry based on a rat plasma metabolomics strategy, J. Pharmaceut. Biomed. , 156 (2018) 221-231. [22] Q. Wan, R. Jiang, L. Guo, S. Yu, M. Liu, J. Tian, G. Liu, F. Deng, X. Zhang, Y. Wei, Novel Strategy toward AIE-Active Fluorescent Polymeric Nanoparticles from Polysaccharides: Preparation and Cell Imaging, ACS Sustain. Chem. Eng., 5 (2017) 9955-9964. [23] Y. Shi, R. Jiang, M. Liu, L. Fu, G. Zeng, Q. Wan, L. Mao, F. Deng, X. Zhang, Y. Wei, Facile synthesis of polymeric fluorescent organic nanoparticles based on the self-polymerization of dopamine for biological imaging, Mater. Sci. Eng. C-Mater., 77 (2017) 972-977. [24] M. Liu, J. Ji, X. Zhang, X. Zhang, B. Yang, F. Deng, Z. Li, K. Wang, Y. Yang, Y. Wei, Self-polymerization of dopamine and polyethyleneimine: novel fluorescent organic nanoprobes for biological imaging applications, J. Mater. Chem. B, 3 (2015) 3476-3482. [25] W.Z. Yuan, P. Lu, S. Chen, J.W. Lam, Z. Wang, Y. Liu, H.S. Kwok, Y. Ma, B.Z. Tang, Changing the Behavior of Chromophores from Aggregation‐Caused Quenching to Aggregation‐Induced Emission: Development of Highly Efficient Light Emitters in the Solid State, Adv. Mater., 22 (2010) 2159-2163. [26] Q. Wan, R. Jiang, L. Mao, D. Xu, G. Zeng, Y. Shi, F. Deng, M. Liu, X. Zhang, Y. Wei, A powerful “onepot” tool for fabrication of AIE-active luminescent organic nanoparticles through the combination of RAFT polymerization and multicomponent reactions, Mater. Chem. Front., 1 (2017) 1051-1058. [27] R. Jiang, M. Liu, H. Huang, L. Mao, Q. Huang, Y. Wen, Q.-y. Cao, J. Tian, X. Zhang, Y. Wei, Ultrafast

construction and biological imaging applications of AIE-active sodium alginate-based fluorescent polymeric nanoparticles through a one-pot microwave-assisted Döbner reaction, Dyes Pigments, 153 (2018) 99-105. [28] R. Jiang, M. Liu, H. Huang, L. Mao, Q. Huang, Y. Wen, Q.-y. Cao, J. Tian, X. Zhang, Y. Wei, Facile fabrication of organic dyed polymer nanoparticles with aggregation-induced emission using an ultrasound-assisted multicomponent reaction and their biological imaging, J. Colloid Interf. Sci., 519 (2018) 137-144. [29] Q. Wan, Q. Huang, M. Liu, D. Xu, H. Huang, X. Zhang, Y. Wei, Aggregation-induced emission active luminescent polymeric nanoparticles: Non-covalent fabrication methodologies and biomedical applications, Appl. Mater. Today, 9 (2017) 145-160. [30] Z. Long, M. Liu, R. Jiang, Q. Wan, L. Mao, Y. Wan, F. Deng, X. Zhang, Y. Wei, Preparation of water soluble and biocompatible AIE-active fluorescent organic nanoparticles via multicomponent reaction and their biological imaging capability, Chem. Eng. J., 308 (2017) 527-534. [31] L. Huang, S. Yang, J. Chen, J. Tian, Q. Huang, H. Huang, Y. Wen, F. Deng, X. Zhang, Y. Wei, A facile surface modification strategy for fabrication of fluorescent silica nanoparticles with the aggregationinduced emission dye through surface-initiated cationic ring opening polymerization, Mater. Sci. Eng. C-Mater., 94 (2019) 270-278. [32] R. Jiang, H. Liu, M. Liu, J. Tian, Q. Huang, H. Huang, Y. Wen, Q.-y. Cao, X. Zhang, Y. Wei, A facile onepot Mannich reaction for the construction of fluorescent polymeric nanoparticles with aggregationinduced emission feature and their biological imaging, Mater. Sci. Eng. C-Mater., 81 (2017) 416-421. [33] R. Jiang, M. Liu, C. Li, Q. Huang, H. Huang, Q. Wan, Y. Wen, Q.-y. Cao, X. Zhang, Y. Wei, Facile fabrication of luminescent polymeric nanoparticles containing dynamic linkages via a one-pot multicomponent reaction: Synthesis, aggregation-induced emission and biological imaging, Mater. Sci. Eng. C-Mater., 80 (2017) 708-714. [34] X. Zhang, X. Zhang, B. Yang, M. Liu, W. Liu, Y. Chen, Y. Wei, Polymerizable Aggregation Induced Emission Dye Based fluorescent Nanoparticles For Cell Imaging Applications Polym. Chem., 5 (2014) 356-360. [35] X. Zhang, X. Zhang, B. Yang, M. Liu, W. Liu, Y. Chen, Y. Wei, Fabrication of Aggregation Induced Emission Dye-based Fluorescent Organic Nanoparticles via Emulsion Polymerization and Their Cell Imaging Applications, Polym. Chem., 5 (2014) 399-404. [36] N.L. Leung, N. Xie, W. Yuan, Y. Liu, Q. Wu, Q. Peng, Q. Miao, J.W. Lam, B.Z. Tang, Restriction of Intramolecular Motions: The General Mechanism behind Aggregation‐Induced Emission, Chem-Eur. J., 20 (2014) 15349-15353. [37] Q.-y. Cao, R. Jiang, M. Liu, Q. Wan, D. Xu, J. Tian, H. Huang, Y. Wen, X. Zhang, Y. Wei, Microwaveassisted multicomponent reactions for rapid synthesis of AIE-active fluorescent polymeric nanoparticles by post-polymerization method, Mater. Sci. Eng. C-Mater., 80 (2017) 578-583. [38] Q.-y. Cao, R. Jiang, M. Liu, Q. Wan, D. Xu, J. Tian, H. Huang, Y. Wen, X. Zhang, Y. Wei, Preparation of AIE-active fluorescent polymeric nanoparticles through a catalyst-free thiol-yne click reaction for bioimaging applications, Mater. Sci. Eng. C-Mater., 80 (2017) 411-416. [39] H. Huang, D. Xu, M. Liu, R. Jiang, L. Mao, Q. Huang, Q. Wan, Y. Wen, X. Zhang, Y. Wei, Direct encapsulation of AIE-active dye with β cyclodextrin terminated polymers: Self-assembly and biological imaging, Mater. Sci. Eng. C-Mater., 78 (2017) 862-867. [40] J. Tian, R. Jiang, P. Gao, D. Xu, L. Mao, G. Zeng, M. Liu, F. Deng, X. Zhang, Y. Wei, Synthesis and cell imaging applications of amphiphilic AIE-active poly (amino acid) s, Mater. Sci. Eng. C-Mater., 79 (2017)

563-569. [41] D. Xu, M. Liu, Q. Huang, J. Chen, H. Huang, F. Deng, Y. Wen, J. Tian, X. Zhang, Y. Wei, One-step synthesis of europium complexes containing polyamino acids through ring-opening polymerization and their potential for biological imaging applications, Talanta, 188 (2018) 1-6. [42] H. Huang, M. Liu, Q. Wan, R. Jiang, D. Xu, Q. Huang, Y. Wen, F. Deng, X. Zhang, Y. Wei, Facile fabrication of luminescent hyaluronic acid with aggregation-induced emission through formation of dynamic bonds and their theranostic applications, Mat. Sci. Eng. C-Mater., 91 (2018) 201-207. [43] C.W.T. Leung, Y. Hong, S. Chen, E. Zhao, J.W. Lam, B.Z. Tang, A Photostable AIE Luminogen for Specific Mitochondrial Imaging and Tracking, J. Am. Chem. Soc., 135 (2013) 62-65. [44] Y. Liu, C. Deng, L. Tang, A. Qin, R. Hu, J.Z. Sun, B.Z. Tang, Specific Detection of d-Glucose by a Tetraphenylethene-Based Fluorescent Sensor, J. Am. Chem. Soc., 133 (2011) 660-663. [45] H. Shi, R.T. Kwok, J. Liu, B. Xing, B.Z. Tang, B. Liu, Real-Time Monitoring of Cell Apoptosis and Drug Screening Using Fluorescent Light-Up Probe with Aggregation-Induced Emission Characteristics, J. Am. Chem. Soc., 134 (2012) 17972-17981. [46] H. Shi, J. Liu, J. Geng, B.Z. Tang, B. Liu, Specific Detection of Integrin αvβ3 by Light-Up Bioprobe with Aggregation-Induced Emission Characteristics, J. Am. Chem. Soc., 134 (2012) 9569-9572. [47] Z. Wang, S. Chen, J.W. Lam, W. Qin, R.T. Kwok, N. Xie, Q. Hu, B.Z. Tang, Long-Term Fluorescent Cellular Tracing by the Aggregates of AIE Bioconjugates, J. Am. Chem. Soc., 135 (2013) 8238-8245. [48] H. Wang, E. Zhao, J.W. Lam, B.Z. Tang, AIE luminogens: emission brightened by aggregation, Mater. Today, 18 (2015) 365-377. [49] Z. Huang, Y. Gu, X. Liu, L. Zhang, Z. Cheng, X. Zhu, Metal ‐ Free Atom Transfer Radical Polymerization of Methyl Methacrylate with ppm Level of Organic Photocatalyst, Macromol. Rapid Comm., 38 (2017) 1600461. [50] L. Shi, L. Wang, J. Chen, J. Chen, L. Ren, X. Shi, Y. Wang, Modifying graphene oxide with short peptide via click chemistry for biomedical applications, Appl. Mater. Today, 5 (2016) 111-117. [51] M. Ouchi, T. Terashima, M. Sawamoto, Transition metal-catalyzed living radical polymerization: toward perfection in catalysis and precision polymer synthesis, Chem. Rev., 109 (2009) 4963-5050. [52] K. Matyjaszewski, J. Xia, Atom Transfer Radical Polymerization, Chem. Rev., 101 (2001) 2921-2990. [53] P.V. Mendonça, S.E. Averick, D. Konkolewicz, A.C. Serra, A.V. Popov, T. Guliashvili, K. Matyjaszewski, J.F.J. Coelho, Straightforward ARGET ATRP for the Synthesis of Primary Amine Polymethacrylate with Improved Chain-End Functionality under Mild Reaction Conditions, Macromolecules., 47 (2014) 4615-4621. [54] C. Cheng, E. Khoshdel, K.L. Wooley, Facile one-pot synthesis of brush polymers through tandem catalysis using Grubbs' catalyst for both ring-opening metathesis and atom transfer radical polymerizations, Nano Lett., 6 (2006) 1741-1746. [55] W. Yu, Y. Zhang, B. Parker, K. Matyjaszewski, ATRP of MMA with ppm levels of iron catalyst, Macromolecules., 44 (2011) 4022-4025. [56] J.T. Yeh, W.C. Chen, S.R. Liu, S.P. Wu, A coumarin-based sensitive and selective fluorescent sensor for copper(II) ions, NEW. J. CHEM., 38 (2014) 4434-4439. [57] N.J. Treat, H. Sprafke, J.W. Kramer, P.G. Clark, B.E. Barton, J. Read de Alaniz, B.P. Fors, C.J. Hawker, Metal-free atom transfer radical polymerization, J. Am. Chem. Soc., 136 (2014) 16096-16101. [58] Z. Huang, Y. Gu, X. Liu, L. Zhang, Z. Cheng, X. Zhu, Metal-Free Atom Transfer Radical Polymerization of Methyl Methacrylate with ppm Level of Organic Photocatalyst, MACROMOL. RAPID. COMM., 38 (2016).

[59] X. Zhang, X. Zhang, B. Yang, J. Hui, M. Liu, Z. Chi, S. Liu, J. Xu, Y. Wei, Facile Preparation and Cell Imaging Applications of Fluorescent Organic Nanoparticles that Combine AIE Dye and Ring-opening Polymerization, Polym. Chem., 5 (2014) 318-322. [60] G. Zeng, M. Liu, R. Jiang, C. Heng, Q. Huang, L. Mao, J. Hui, F. Deng, X. Zhang, Y. Wei, Surface grafting of Eu 3+ doped luminescent hydroxyapatite nanomaterials through metal free light initiated atom transfer radical polymerization for theranostic applications, Mat. Sci. Eng. C-Mater., 77 (2017) 420-426. [61] P. Alam, N.L.C. Leung, H. Su, Z. Qiu, R.T. Kwok, J.W. Lam, B.Z. Tang, A Highly Sensitive Bimodal Detection of Amine Vapours Based on Aggregation Induced Emission of 1, 2 ‐ Dihydroquinoxaline Derivatives, Chem. Eur. J., 23 (2017) 14911-14917. [62] G. Feng, C.Y. Tay, Q.X. Chui, R. Liu, N. Tomczak, J. Liu, B.Z. Tang, D.T. Leong, B. Liu, Ultrabright organic dots with aggregation-induced emission characteristics for cell tracking, Biomaterials, 35 (2014) 8669-8677. [63] M. Huo, Q. Ye, H. Che, X. Wang, Y. Wei, J. Yuan, Polymer Assemblies with Nanostructure-Correlated Aggregation-Induced Emission, Macromolecules, 50 (2017) 1126-1133. [64] L. Mao, M. Liu, D. Xu, Q. Wan, Q. Huang, R. Jiang, Y. Shi, F. Deng, X. Zhang, Y. Wei, Fabrication and biological imaging of polyhedral oligomeric silsesquioxane cross-linked fluorescent polymeric nanoparticles with aggregation-induced emission feature, Appl. Surf. Sci., 423 (2017) 469-475.

Highlights ► Fabrication of AIE-active fluorescent polymeric nanoparticles through photo-mediated polymerization ► The particle size could be adjusted by tuning the ratio of hydrophobic and hydrophilic monomers ► The fluorescent properties could be adjusted by tuning the ratio of hydrophobic and hydrophilic monomers ► This method is a promising strategy for fabrication of AIE-active functional materials

Graphical abstract

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.

Author contributions section The authors contributions of Jiande Dong and Ruming Jiang (Data curation; Formal analysis, Writing original draft) The authors contributions of Weimin Wan, Haijun Ma, Hongye Huang (Data curation; Methodology) The authors contributions of Yulin Feng, Yanfeng Dai (Methodology; Resources; Funding acquisition;) The authors contributions of Hui Ouyang, Xiaoyong Zhang, Yen Wei (Conceptualization, Supervision; Funding acquisition; Resources; Writing - review & editing)