Gongyan Liu

A pH-responsive drug delivery system with an aggregation-induced emission feature for cell imaging and intracellular drug delivery

A pH-responsive fluorescent vehicle based on aggregation-induced emission (AIE) has been developed as a drug delivery system, which could be traced in cancer cells and further exhibited high cytotoxicity in tumor cells due to its excellent sensitivity at the endosomal pH.

In situ synthesis of multidentate PEGylated chitosan modified gold nanoparticles with good stability and biocompatibility

To realize desirable functions in the rather complex biological systems, a suitable surface coating is desirable for gold nanoparticles, which plays an important role in their colloidal stability and biocompatibility. In this work, a novel multidentate PEGylated chitosan derivative was synthesized by conjugating PEG and dithiolane lipoic acid (LA) to the chitosan backbone. Under reduction conditions, gold nanoparticles (AuNPs) could be in situ formed by the electrostatic interaction between amino groups of the chitosan derivative and gold chloride ions (AuCl4−), with their surface covalently coated by the multidentate PEGylated chitosan via the disulfide bond from LA. After the surface modification, such AuNPs exhibited remarkable colloidal stabilities under extreme conditions, including high salt conditions and complex biological media containing serum. Moreover, the multidentate PEGylated chitosan also provided AuNPs with good biocompatibility and low cytotoxicity, resistance of protein adsorption and anti-phagocytosis by RAW 264.7 cells. This kind of AuNP was expected to be a promising platform for applications in nanomedicine.

PEGylated chitosan protected silver nanoparticles as water-borne coating for leather with antibacterial property

Development of eco-labeled and effectively antibacterial coatings for final leather products has been desiderated both by industry and by consumers. Herein, PEGylated chitosan modified silver nanoparticles (PEG-g-CS@AgNPs) were prepared and characterized by UV-vis spectroscopy, transmission electron microscopy and dynamic light scattering. The antimicrobial activity of such silver nanoparticles was investigated against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), exhibiting much lower minimum inhibitory concentration (MIC) than chitosan or PEG-g-CS. Water-borne coating was formed by immobilizing the PEG-g-CS@AgNPs onto the leather surface through the electrostatic interaction between amino groups of chitosan and carboxyl groups of leather collagen. Scanning electron microscopy and water contact angle were employed to study the coatings morphology and hydrophilicity, respectively. After coating, leather samples showed significantly high bactericidal efficiency with reusability after release of dead cells from the coating by simply water washing. The excellent antibacterial property of PEG-g-CS@AgNPs coating was ascribed to the combination of bacteria-resistance and bacteria-release by PEGylation, and dual bacteria-killing based on chitosan and Ag+ release.

Polymeric micelles based on PEGylated chitosan-g-lipoic acid as carrier for efficient intracellular drug delivery:

To develop a drug delivery system with long circulation and controlled drug release in cancer cells, polymeric micelles based on PEGylated chitosan-g-lipoic acid were prepared to use as a drug delivery platform. These micelles possessed good stability and were stable in physiological environment and high salt concentrations. The in vitro drug release results implied that the drug carrier could maintain their stability and minimize the payload leakage in systemic circulation, but release drugs faster under intracellular redox condition. Furthermore, the cellular uptake and therapeutic efficacy of the drug carrier were evaluated in vitro, and the results demonstrated that the drug carrier could escape from the endo/lysosomes of tumor cells effectively and present high cytotoxicity to tumor cells. Therefore, this drug delivery system has the potential to serve as a drug carrier for cancer therapy.

A fully absorbable biomimetic polymeric micelle loaded with cisplatin as drug carrier for cancer therapy

Abstract cis-dichlorodiammineplatinum(II) (CDDP)-loaded polymeric micelles for cancer therapy have been developed to reduce the serious side effects of cisplatin CDDP. Herein, polymeric micelles incorporated with cisplatin are prepared based on the complexation between CDDP and hydrophilic poly (L-glutamic acid)-b-poly (2-methacryloyloxyethyl phosphorylcholine) (PLG-b-PMPC) diblock copolymers. These CDDP-loaded micelles possess an average size of 91 nm with narrow distribution, providing remarkable stability in media containing proteins. The release of CDDP from the micelles is faster at pH 5.0 and pH 6.0 than that at pH 7.4 and in a sustained manner without initial burst release. In addition, there is almost no difference in cellular uptake between these CDDP-loaded micelles and free CDDP. Moreover, in vitro cytotoxicity test shows they possess high efficacy to kill 4T1 cells as compared with free drug. Thus, PLG-b-PMPC copolymer might be a promising carrier for CDDP incorporating in cancer therapy.

A biomimetic and pH-sensitive polymeric micelle as carrier for paclitaxel delivery

Abstract As nano-scale drug delivery systems, smart micelles that are sensitive to specific biological environment and allowed for target site-triggered drug release by reversible stabilization of micelle structure are attractive. In this work, a biocompatible and pH-sensitive copolymer is synthesized through bridging poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC) block and poly (D, L-lactide) (PLA) block by a benzoyl imine linkage (Blink). Biomimetic micelles with excellent biocompatibility based on such PLA-Blink-PMPC copolymer are prepared as carriers for paclitaxel (PTX) delivery. Due to the rapid breakage of the benzoyl imine linkage under acidic condition, the micelle structure is disrupted with accelerated PTX release. Such pH-sensitive triggered drug release behavior in synchronization with acidic conditions at tumor site is helpful for improving the utilization of drug and facilitating antitumor efficacy. These micelles can be used as promising drug delivery systems due to their biocompatible and smart properties.

Facile fabrication of a biomass-based film with interwoven fibrous network structure as heterogeneous catalysis platform

The stable and efficient immobilization of silver nanoparticles (AgNPs) on/into processable biomass-based macro-support with porous networks is a promising and sustainable strategy to achieve both high catalytic activity and excellent reusability for heterogeneous catalysis. In this work, a collagenic composite film was facilely fabricated at room temperature, via the self-assembly of natural collagen fibers (CFs) and gallic acid modified silver nanoparticles (GA@AgNPs) induced by chromium (III) cross-linking in water. The morphology and microstructure of such GA@AgNPs-Cr-CFs composite film was investigated by Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The results revealed that the cross-linking based on the coordinated complexation between chromium ions (Cr3+) and carboxyl groups on CFs and GA@AgNPs played the critical role in the interwoven of collagen fibers, leading to a three dimensional (3D) interconnected porous network of the composite film with simultaneously incorporation and high payload of silver nanoparticles. Furthermore, this GA@AgNPs-Cr-CFs composite film exhibited excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP), taking the advantage of its high specific surface area given by the interwoven fibrous network structure. More than that, such sustainable composite catalyst could be easily recovered and reused for ten cycles because of its high stability based on cross-linking. This catalytic platform constructed by natural fibers, noble metal nanoparticles and trivalent metal ions showed a sustainable avenue for heterogeneous catalytic system.