Jianwen Tian

Surface modification of carbon nanotubes by combination of mussel inspired chemistry and SET-LRP

An efficient and facile strategy was developed for the surface modification of functional carbon nanotubes (CNTs) by the combination of mussel inspired chemistry and single electron transfer living radical polymerization (SET-LRP). This method involves the dopamine (DA) formation of polydopamine (PDA), which was coated on the surface of pristine CNTs via self-polymerization in alkaline solution. Then, the Br-containing initiator was covalently attached on the surface of CNTs modified with PDA. Subsequently, the poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) was in situ grown on the surface of Br-containing CNTs via the SET-LRP method. The resulting functional materials were characterized by a series of characterization techniques. It was demonstrated that PPEGMA chains were successfully conjugated to the surface of CNTs via a combination of mussel inspired chemistry and SET-LRP. After modifying with PPEGMA, the functional CNTs retain their pristine structure, but their dispersibility was significantly improved in polar and nonpolar solutions. Compared with previous methods, the strategy developed in this work is rather simple and effective. More importantly, due to the universality of mussel inspired chemistry, this novel strategy could also be used for the surface modification of many other materials.

Fabrication and biological imaging application of AIE-active luminescent starch based nanoprobes.

Fabrication of water dispersible, biocompatible and ultrabright luminescent polymeric nanoprobes (LPNs) has been the subject of great research interest. Although a number of LPNs have been fabricated previously through different strategies, the preparation of luminescent carbohydrate polymers with aggregation-induced emission (AIE) characterstic has received only limited attention. In this work, we reported for the first time that AIE-active luminescent starch can be facilely fabricated via mixing the aldehyde-contained AIE dye 4-(1,2,2-triphenylvinyl) benzaldehyde (TPE-CHO) with carboxyl methyl starch sodium (CMS) and amino phenylboronic acid in a one-pot procedure, in which aminophenylboronic acid can serve as the linkage for conjugation of TPE-CHO and CMS. The final products (TPE-CMS LPNs) were characterized by a number of characterization techniques such as (1)H nuclear magnetic resonance spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and fluorescence Spectroscopy in detail. To examine their biomedical application potential, the biocompatibility as well as cell uptake behavior of TPE-CMS LPNs were further determined. We demonstrated that TPE-CMS LPNs showed high water dispersibility and strong fluorescence, well biocompatibility and efficient cell internalization behavior, making them promising candidates for various biomedical applications.

Mussel inspired preparation of highly dispersible and biocompatible carbon nanotubes

The biomedical applications of carbon nanotubes (CNTs) have been intensively investigated. However, poor water dispersibility and obvious toxicity of pristine CNTs are still two major issues for their biomedical applications. Although great efforts have been devoted to solving these problems, a simple and effective strategy for preparation of CNTs with high water dispersibility and desirable biocompatibility is still of great research interest. Herein, surface modification of CNTs with a biocompatible polymer polyethylene glycol (PEG) via a mussel inspired strategy has been developed. The dispersibility as well as biocompatibility of these PEGylated CNTs (named as CNT-poly(PEGMA-co-IA-DA)) was subsequently investigated. These PEGylated CNTs showed remarkable enhancement of dispersibility in aqueous and organic solvents. More importantly, as evidenced by cell viability and reactive oxygen species results, these PEGylated CNTs showed negative toxicity toward cancer cells. Therefore the PEGylated strategy described in this work can provide a general platform for fabrication of multifunctional biomaterials for various biomedical applications because of the advantages of mussel inspired chemistry and the excellent properties of PEGylated materials.

Microwave-assisted multicomponent reactions for rapid synthesis of AIE-active fluorescent polymeric nanoparticles by post-polymerization method

The development of simple and effective methods for synthesis of fluorescent polymeric nanoparticles (FPNs) with aggregation-induced emission (AIE) plays an important role for the biomedical applications of AIE-active FPNs. In present work, we developed a facile strategy for the fabrication of AIE-active FPNs by a post-polymerization method based on the microwave-assisted Kabachnik-Fields (KF) reaction, which can conjugate with poly(PEGMA-NH2), AIE-active dye (TPE-CHO) and diethyl phosphate (DP) under microwave irradiation within 5min. The characterization results confirm that PEGMA-TPE FPNs are successfully prepared through the microwave-assisted KF reaction. The resultant AIE-active FPNs show high water dispersity, intensive fluorescence and low cytotoxicity. These features make these AIE-active FPNs great potential for biomedical applications. Moreover, the microwave-assisted KF reaction is simple, fast, atom economy that should be a general strategy for the fabrication of various multifunctional AIE-active FPNs. We believe this work will open up a new avenue for the preparation of AIE-active functional materials with great potential for different applications.

Toward the development of versatile functionalized carbon nanotubes

Surface modification of carbon nanotubes (CNT) with polymers is a general and effective strategy to improve the performance of CNTs for applications. In this work, a facile strategy to synthesize hydrophobic and hydrophilic CNT by mussel inspired chemistry and Single-Electron Transfer Living Radical Polymerization (SET-LRP) was developed for the first time. The successful synthesis of these CNT–polymer composites was confirmed by a series of characterization techniques including transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis and X-ray photoelectron spectra. These CNT exhibited obviously enhanced dispersibility in water and different organic solvents after they were surface functionalized with hydrophilic and hydrophobic polymers. The synthetic strategy is convenient, versatile and environmentally friendly and can be extended for fabrication of many other polymer nanocomposites. Therefore, the method developed in the present work might open a new route to fabricate functional CNT–polymer composites for different applications.

A facile one-pot Mannich reaction for the construction of fluorescent polymeric nanoparticles with aggregation-induced emission feature and their biological imaging

Multicomponent reactions (MCRs) have recently attracted great attention as one of the most important tools for the construction of various organic compounds in modern organic chemistry. In this work, we introduced an efficient one-pot strategy to successfully fabricate the fluorescent polymeric nanoparticles (FPNs) with aggregation-induced emission (AIE) characteristic via the conjugation of hyperbranched polyamino compound polyethyleneimine (PEI), AIE dye (named as PhE-OH) and paraformaldehyde (PF) through a Mannich reaction. The final amphiphilies (PEI-PF-PhE) can self-assemble into micelles in aqueous solution. We demonstrated PEI-PF-PhE FPNs showed high water dispersity, intense orange-yellow fluorescence, excellent photostability, low toxicity and high cell imaging performance. As compared with other construction strategies, the one-pot Mannich reaction possesses a number of advantages, such as simplicity, atom economy, high-efficiency and multifunctional potential. Combined with the remarkable properties of the AIE-active FPNs and the one-pot Mannich reaction, we could expect that the strategy developed in this work should be a useful tool for construction of various AIE-active functional materials for biomedical applications.

Preparation of AIE-active fluorescent polymeric nanoparticles through a catalyst-free thiol-yne click reaction for bioimaging applications

Fluorescent polymeric nanoparticles (FPNs) with aggregation-induced emission (AIE) characteristics have attracted much attention for biomedical applications due to their remarkable AIE feature, high water dispersity and desirable biocompatibility. The development of facile and effective strategies for fabrication of these AIE-active FPNs therefore should be of great importance for their biomedical applications. In this work, we reported that a catalyst-free thiol-yne click reaction can be utilized for fabrication of AIE-active FPNs in short reaction time and even without protection of inert gas. The results indicated that the obtained AIE-active amphiphilic copolymers (PEGMA-PhE) can readily self-assemble into luminescent nanoparticles (PEGMA-PhE FPNs) with high water dispersity, uniform size and morphology, red fluorescence. Cell viability examination and cell uptake behavior of PEGMA-PhE FPNs confirmed that these AIE-active FPNs possess low toxicity towards cells and can be easily internalized by cells through non-specific route. Therefore the remarkable properties of PEGMA-PhE FPNs such as high water dispersity, AIE-active fluorescence and nanoscale size as well as excellent biocompatibility make them promising for biomedical applications.

Synthesis and cell imaging applications of amphiphilic AIE-active poly(amino acid)s

The poly(amino acid)s based biomaterials have attracted great research attention over the past few decades because of their biocompatibility, biodegradability and well designability. Although much progress has achieved in the synthesis and biomedical applications of poly(amino acid)s, the synthesis of luminescent poly(amino acid)s has been rarely reported. In this work, novel amphiphilic luminescent poly(amino acid)s with aggregation-induced emission (AIE) feature have been synthesized by a new approach of controlling N-carboxy anhydride (NCA) ring-opening polymerization, in which hydrophobic 2-(4-aminophenyl)-3-(10-hexadecyl-4H-phenothiazin-3-yl)acrylonitrile (Phe-NH2) with AIE feature was used as initiator and hydrophilic oligomeric glycol functionalized glutamate (OEG-glu) NCA was acted as monomer. The successful synthesis of final Phe-OEG-Pglu polymers was confirmed by different characterization techniques. Phe-OEG-Pglu polymers possess amphiphilic properties and can self-assemble into luminescent polymeric nanoparticles (LPNs). Based on cellular imaging experiments, we demonstrated that Phe-OEG-Pglu LPNs have great potential for bio-imaging applications due to their attractive properties including strong fluorescence intensity, great water dispersibility, excellent biocompatibility and high cellular uptake efficiency.

The one-step acetalization reaction for construction of hyperbranched and biodegradable luminescent polymeric nanoparticles with aggregation-induced emission feature

The development of luminescent bioprobes based on organic dyes with aggregation-induced emission (AIE) characteristic has attracted great attention in recent years. In this work, we reported for the first time that AIE-active luminescent polymeric nanoparticles (LPNs) can be facilely prepared via a one-step acetalization reaction, which can be used to conjugate the aldehyde group containing AIE dye (PTH-CHO) and methoxypolyethylene glycols (mPEG-CHO) with a commercially available dendritic polyester (H40) using p-toluenesulfonic acid (TsOH) as the catalyst. As-prepared star-shaped hyperbranched luminescent polymers (named as H40-mPEG-mPTH) were prone to self-assemble into core-shell nanoparticles in aqueous solution because of their amphiphilic structure, in which hydrophobic components (such as PTH-CHO and H40) were encapsulated in the core while the hydrophilic components (mPEG-CHO) were acted as the shell. The final AIE-active H40-mPEG-mPTH LPNs displayed uniform spherical structure, strong fluorescence, excellent photostability and high water dispersity. Furthermore, biological evaluation results demonstrated that H40-mPEG-mPTH LPNs possess low toxicity and excellent biocompatibility, indicating their great potential for biomedical applications. Taken together, we reported a novel strategy for the construction of hyperbranched and biodegradable LPNs with AIE feature through a one-step acetalization reaction, which can be also utilized for construction of many other AIE-active LPNs with a variety structure and properties.

Construction of biodegradable and biocompatible AIE-active fluorescent polymeric nanoparticles by Ce(IV)/HNO3 redox polymerization in aqueous solution

Aggregation-induced emission (AIE) active fluorescence polymeric nanoparticles (FPNs) have recently received increasing interests for biomedical applications such as cell imaging, drug delivery, disease diagnosis and treatment. Fabricated strategies of AIE-active FPNs with high efficiency, simplification and tenderness are still passionately pursued to promote the development of theranostic systems. In this work, we develop a facile method for the preparation of AIE-active FPNs by adopting Ce(IV)/HNO3 redox polymerization under near room temperature. Thus-prepared FPNs (named as PEG-PLC-1) possess unique AIE feature, great water dispersity, excellent biocompatibility and biodegradability because of the conjugation of ultra-bright AIE dye (PhE-alc) and biodegradable PEG-PCL linear copolymers. The 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), UV-Visible and fluorescence spectrometers were used to confirm the successful fabrication of AIE-active FPNs. Cell viability and cellular uptake behavior of PEG-PLC-1 FPNs were further investigated for their potential biomedical applications. Results demonstrated that PEG-PLC-1 FPNs are high water dispersity, intensive luminescence and low cytotoxicity, making them very attractive for biomedical applications. More importantly, the method for the fabrication of AIE-active biodegradable FPNs can be occurred under rather facile conditions (e.g., low temperature, free of metal catalysts, common chain transfer agent and aqueous solution) and are specially used for fabrication of AIE-active polysaccharides with poor organic solubility.