Liucheng Mao

Towards development of a versatile and efficient strategy for fabrication of GO based polymer nanocomposites

Surface modification of graphene oxide (GO) with polymers is of particular importance for its applications. Although much progress has been made in the surface modification of GO, the surface modification of GO with synthetic polymers in aqueous solution has demonstrated to be problematic. In the present work, we report for the first time a versatile and effective method for the surface modification of GO with synthetic polymers in aqueous solution taking advantage of mussel inspired chemistry. Poly(ethylene glycol) methyl ether methacrylate and itaconic anhydride (IA) monomers were chosen to prepare hydrophilic polymers (poly(IA-co-PEGMA)) via free radical living polymerization. These hydrophilic polymers were further reacted with dopamine through ring-opening reaction between IA and dopamine, which could be highly efficiently attached to the GO surface via mussel inspired chemistry using dopamine as the adhesion component. The successful modification of GO with polymers was confirmed by using a series of characterization techniques. The resulting GO–polymer nanocomposites displayed great dispersibility in aqueous and organic solutions, making them promising for various applications. Compared with previous methods, the biomimic strategy described in this work could facilely and effectively immobilize synthetic polymers on GO in aqueous solution at room temperature and under an air atmosphere. More importantly, this strategy could also be utilized for the fabrication of almost any polymer nanocomposite because of the designability and applicability of living polymerization, and the versatility and strong adhesion of dopamine.

Fabrication and biomedical applications of AIE active nanotheranostics through the combination of a ring-opening reaction and formation of dynamic hydrazones

Aggregation-induced emission (AIE) dyes based on fluorescent organic nanoparticles (FONs) have attracted increasing interest over the past few years. However, the biomedical applications of AIE dyes based on FONs for simultaneous biological imaging and therapeutic applications have rarely been reported thus far. In this study, an amino group terminated phenothiazine (named as ATPHE) with AIE features and red fluorescence was synthesized and utilized for the fabrication of AIE active FONs via a facile one-pot strategy, which relied on the ring-opening reaction between ATPHE and an anhydride containing compound. Then, the keto group of the AIE active polymeric intermediate was subsequently conjugated with hydrazide terminated polyethylene glycol (HTPEG) through the formation of hydrazone bonds. These amphiphilic AIE active copolymers are readily self-assembled into nanoscale particles in an aqueous solution, which resulted in strong luminescence and good water dispersibility of the final HTPEG@ATPHE-co-BTDA FONs. The excellent physicochemical and biological properties of HTPEG@ATPHE-co-BTDA FONs give them high potential for biological imaging and controlled drug delivery applications. Taken together, we developed a simple strategy for the fabrication of AIE active nanoparticles, which are promising for biological imaging and controlled drug delivery.

Carbon nanotube based polymer nanocomposites: biomimic preparation and organic dye adsorption applications

The development of highly efficient adsorbents for the removal of organic dyes from wastewater has attracted much attention recently. Surface modification of adsorbents with polymers is a general strategy for enhancement of their adsorption capability. In this work, a novel strategy of a combination of mussel inspired chemistry and SET-LRP has been developed for the fabrication of highly efficient adsorbents, poly(sodium-p-styrene sulfonate) modified multi-walled carbon nanotubes (CNTs), for the first time. The adsorption applications of these CNT based polymer nanocomposites for the removal of a cationic dye (methylene blue, MB) from a water solution were also examined. The successful preparation of these CNT based polymer nanocomposites was confirmed by a series of characterization techniques. Furthermore, the influence of adsorption parameters including contact time, concentration of MB, adsorption temperature and time has been investigated. According to the experimental data, the adsorption capacity of MB was directly proportional to the contact time, while inversely proportional to the temperature. The maximum adsorption capacity of MB for CNT-PDA-PSPSH was 160 mg g−1, demonstrating the excellent adsorptive property of functional CNTs for MB. The method described in this work for the preparation of CNT based polymer nanocomposites is simple, effective and general, and could be a universal strategy for preparation of highly efficient adsorbents for environmental applications.

Facile Fabrication of PEGylated Fluorescent Organic Nanoparticles with Aggregation-Induced Emission Feature via Formation of Dynamic Bonds and Their Biological Imaging Applications.

Driven by the high demand for sensitive and specific tools for optical imaging, fluorescent nanoprobes with various working mechanisms and advanced functionalities are flourishing at an incredible speed. This work reports the design and fabrication of aggregation-induced emission (AIE)-active fluorescent organic nanoparticles (FNPs) via forming dynamic phenyl borate between diol containing hydrophobic AIE dye (APD-PhCHO) and phenylboronic acid pendant hydrophilic polymers (PEGMA-VPBA) within 30 min. The final AIE-active APD-PhCHO-PEGMA-VPBA FNPs display high water dispersibility and strong fluorescence emission because of their amphiphilic properties and AIE feature. Biological evaluation suggests that APD-PhCHO-PEGMA-VPBA FNPs possess negative effect on HeLa cells and desirable optical properties for biological imaging. More importantly, phenyl borate is a dynamic bond with pH and glucose responsiveness. Furthermore, different functions can be designed and introduced into these AIE-active systems through adoption of different monomers for good applicability of free radical polymerization. Therefore, this work provides a novel platform for preparation of multifunctional AIE-active nanosystems with responsiveness for various 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.

Direct encapsulation of AIE-active dye with β cyclodextrin terminated polymers: Self-assembly and biological imaging

Aggregation-induced emission (AIE) phenomenon has attracted great attention recently and been extensively explored for biomedical applications. Nevertheless, the direct utilization of AIE-active dyes for biomedical applications has demonstrated to be enormous challenge owing to the hydrophobic nature of these AIE-active dyes. In this work, we reported the fabrication of amphiphilic AIE-active copolymers through the specific host-guest interaction between β cyclodextrin (β-CD) and an adamantine terminating tetraphenylethene derivative (TPE-Ad). In this construction system, β-CD was acted as the bridge to link TPE-Ad with PEG. The TPE-β-CD-PEG copolymers were characterized by various equipments in detail. Cytocompatibility and cell uptake behavior of TPE-β-CD-PEG were also examined to evaluate their biomedical application potential. Results demonstrated that TPE-β-CD-PEG copolymers were prone to self-assemble into luminescent nanoparticles, which exhibited high water dispersity, AIE feature and excellent biocompatibility. These features endowed TPE-β-CD-PEG great potential for biomedical applications.

A powerful “one-pot” tool for fabrication of AIE-active luminescent organic nanoparticles through the combination of RAFT polymerization and multicomponent reactions

Multicomponent reactions (MCRs) have recently received increasing attention for the synthesis of structural complexity in a single step from three or more reactants. They have also been considered as a powerful tool for the construction of sequence-controlled multifunctional polymers owing to their good substrate adaptability, simple operation and high efficiency. In this work, we reported methods that are a combination of the three-component mercaptoacetic acid locking imine (MALI) reaction and reversible addition fragmentation chain transfer (RAFT) polymerization in one pot to form luminescent organic nanoparticles (LONs) with aggregation-induced emission (AIE) features, high-brightness, great water dispersibility, ultra-small nanoscale size and excellent biocompatibility. In the reaction system, the MALI reaction and RAFT polymerization happened simultaneously in a “one-pot” route. On the one hand, the AIE-active organic dye with one amino group ((Z)-3-(4-aminophenyl)-2-(10-hexadecyl-10H-phenothiazin-3-yl)acrylonitrile) (named as Phe-NH2) was conjugated with an aldehyde-containing monomer (10-undecenal) by the MALI reaction, while the aldehyde-containing monomer was copolymerized with the hydrophilic monomer polyethylene glycol methyl methacrylate (PEGMA) through RAFT polymerization at the same time. Compared with other fabrication strategies, “one-pot” strategies possess some advantages such as high efficiency, simplicity, and atom economy. On the other hand, due to the good applicability of RAFT polymerization and the MALI reaction, many other multifunctional AIE-active LONs could also be fabricated via adjusting the function of the substrates. Therefore, this strategy should be a general and important route for fabrication of AIE-active materials for different applications.

Fabrication of amphiphilic fluorescent nanoparticles with an AIE feature via a one-pot clickable mercaptoacetic acid locking imine reaction: synthesis, self-assembly and bioimaging

Fluorescent organic nanoparticles (FNPs) with intensive luminescence are widely applied in various biomedical fields, but the malicious aggregation caused quenching effect of conventional organic dyes hampers their biomedical application. In this work, we report a facile and highly efficient method for fabrication of FNPs with a stable cross-linked structure and enhanced luminescence via a one-pot mercaptoacetic acid locking imine reaction, in which a hydrophobic aggregation induced emission (AIE) dye (AHAn) and hydrophilic polylysine (Plys) were used as two reaction components, while mercaptoacetic acid acted as the lock to conjugate AHAn and Plys. The final amphiphilic fluorescent materials (Plys&AHAn&Plys) are readily formed FNPs in aqueous solution and exhibit high water dispersibility and strong luminescence. Furthermore, Plys&AHAn&Plys FNPs display low toxicity and good biological imaging performance. Altogether, we have developed a rather facile one-pot multicomponent reaction (MCR) to fabricate AIE active FNPs, which shows many promising properties for biomedical applications. More importantly, the MCR strategy could also be used for fabrication of many other multifunctional AIE active polymeric nanoprobes due to its good substrate adaptability and high efficiency.

Facile synthesis and characterization of poly(levodopa)-modified silica nanocomposites via self-polymerization of levodopa and their adsorption behavior toward Cu2+

AbstractIn this study, a facile surface functionalization method was applied to synthesize poly-levodopa (PDOPA)-modified silica nanocomposites (denoted as SiO2-PDOPA). The adsorption capacity of SiO2-PDOPA was found to be higher than that of unmodified SiO2 NPs. The successful preparation of SiO2-PDOPA was confirmed by Fourier transform infrared spectroscopy, transmission electron microscopy, and thermo gravimetric analysis. The adsorption behavior was investigated using SiO2-PDOPA as adsorbents and Cu2+ as a model heavy metal pollutant. Various adsorption parameters, including contact time, solution pH, temperature, and initial Cu2+ concentrations were studied. The results showed that pH could markedly affect the adsorption process of SiO2-PDOPA to Cu2+. The optimum pH for Cu2+ adsorption was found to be 7.0. The adsorption kinetic data were analyzed using pseudofirst-order, pseudosecond-order, and intraparticle diffusion models. The adsorption isotherms could be described by Langmuir and Freundlich isotherm models. The fitting results showed that the adsorption kinetics and isotherms were better described by the pseudosecond-order and Langmuir model, respectively. The values of thermodynamics constants, including entropy change (ΔS0), enthalpy change (ΔH0), and Gibbs free energy (ΔG0) were determined at different temperatures. Results suggested that the adsorption process of SiO2-PDOPA to Cu2+ is a feasible, endothermic, and spontaneous process.

Facile synthesis of polymeric fluorescent organic nanoparticles based on the self-polymerization of dopamine for biological imaging

Polymeric fluorescent organic nanoparticles (polymer-FONs) have raised considerable research attention for biomedical applications owing to their advantages as compared with fluorescent inorganic nanoparticles and small organic molecules. In this study, we presented an efficient, facile and environment-friendly strategy to produce polymer-FONs, which relied on the self-polymerization of dopamine and polyethyleneimine (PEI) in rather mild conditions. To obtain the final polymer-FONs, aldehyde group-containing copolymers (named as poly(UA-co-PEGMA)) were synthesized by reversible addition-fragmentation chain-transfer polymerization using polyethylene glycol methyl ether methacrylate (PEGMA) and 1-undecen-10-al (UA) as monomers. The dopamine was conjugated onto poly(UA-co-PEGMA) through a multicomponent reaction between UA and dopamine to obtain poly(UA-co-PEGMA)-DA, which was further utilized for preparation of polymer-FONs through self-polymerization of dopamine and PEI. 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescence spectroscopy were employed to characterize the structure, morphology, compositions and optical properties of these polymer-FONs. Cell viability and cell uptake behavior results suggested that these polymer-FONs possess good biocompatibility and can be potentially utilized for biomedical applications. More importantly, the method can be also applied to fabricate many other multifunctional polymer-FONs with great potential for biomedical applications.