Xinxin Sang

Preparations and doxorubicin controlled release of amino-acid based redox/pH dual-responsive nanomicelles

Terpolymers of poly (Lysine-co-N, N-Bis (acryloyl) cystamine-co-β-Phenethylamine) (PLBP) were synthesized in one-pot by Michael addition terpolymerization. The terpolymers self-assembled into nano-sized spherical micelles (84-123nm) with narrow distributions. The surface charge of the nanomicelles (NMs) was depended on solutions pH and showed negative values under physiological conditions (pH7.4), which was beneficial for long circulation without non-specific protein adsorption. Doxorubicin (DOX) was effectively loaded into the NMs for controlled release. The in vitro release profiles exhibited obvious pH and reduction sensitivities in response to the environment mimicking tumor cells. The MTT assays demonstrated that blank NMs were biocompatible, and drug-laden NMs showed a significant cytotoxicity on Hela cells. The NMs could be potentially applied as smart drug delivery systems in cancer therapy.

Micro-nano fabrication of hierarchical PPy/TiO2/Si by continuous self-assembly technology

ABSTRACT Combining TiO2 with conducting polymer could enhance the photoelectric transformation efficiency of absorbed light, due to the formation of P-N heterojunctions. However, few people considered to increase the adsorption efficiency of incident light for the composites. In this manuscript, we demonstrate a facile approach of sequentially assembling TiO2 nanorods and polypyrrole (PPy) on the monocrystalline silicon wafer by the method of hydrothermal synthesis and chemical oxidation. The PPy/TiO2/Si composites with hierarchical structures possessed broadband antireflection and dual P-N heterojunctions, enhancing not only the incident light absorption efficiency but also the utilization efficiency of absorbed light. Thus, PPy/TiO2/Si with hierarchical structures is the excellent candidate materials for the photoelectric device and the photocatalyst.

Preparations of hyperbranched polymer nano micelles and the pH/redox controlled drug release behaviors

Hyperbranched polymer nano micelles (NMs) were prepared through a nucleophilic ring opening polymerization between cystamine and polyethylene glycol diglycidyl ether, followed by a reaction of amino groups and dimethyl maleic anhydride. The NMs showed spheric morphologies with hydrodynamic diameters of 106-120nm. Doxorubicin was loaded in the NMs with loading rate as high as 15.38wt%; The NMs possessed negative zeta potentials in aqueous solutions of pH7.4 due to the carboxyl ions on the particle surfaces, but the zeta potentials were converted to positive ones due to the hydrolysis of amide bonds at pH5.0-6.5, leading to the leaving of carboxyl groups and remaining of amino groups. The disulfide bonds in cystamine were designed in the hyperbranched polymer structures of the NMs, and bonds could be broken by a reducing agent l-glutathione (GSH) (10mM), resulting in a targeted drug release. The smart NMs displayed good biodegradability and biocompatibility, and they could be potentially used in drug controlled release field.

Fabrication of polyaniline/octa-(aminopropylsilsesquioxane) with enhanced electrochemical capacitance and improved cycling stability via in situ polymerization

Taking advantage of cheap raw materials, polyaniline/octa-(aminopropylsilsesquioxane) (PANI/POSS-NH2) composites with hierarchical structures were obtained by a simple and low-cost method of mechanical agitation combined with sonication. The structure, morphology and electrochemical property of PANI/POSS-NH2 were characterized by nuclear magnetic resonance (NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammogram (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS). Compared with pure PANI, PANI/POSS-NH2 exhibited good specific capacitance, due to the high specific surface area of POSS-NH2 and synergetic effects of the two components. Moreover, POSS-NH2 played an important role in improving the cycling stability of PANI/POSS-NH2.

Preparation of pH/redox dual responsive polymeric micelles with enhanced stability and drug controlled release

Stimuli-responsive polymeric micelles were prepared through self-assembly of amphiphilic copolymers poly(ethylene glycol)-poly(γ-benzyl l-glutamate), followed by a core-crosslinking reaction using cystamine as the crosslinking agent. The crosslinked micelles with spherical morphologies in nanometer size showed enhanced stability against dilution and concentrated salt solutions compared to the micelles before crosslinking. Doxorubicin (DOX) as a model drug was encapsulated into the core of micelles through electrostatic interactions between carboxylic acid and DOX. In vitro drug release under pH and redox conditions was investigated. Furthermore, the cytotoxicity of micelles was evaluated before and after drug loading. The endocytosis of DOX-loaded micelles and the intracellular drug release were studied. DOX-loaded micelles exhibited accelerated drug release behaviors in an acidic and reductive environment, and showed an inhibited premature release behavior as compared to the noncrosslinked micelles. Considering their enhanced stability, pH and redox dual triggered responsive characteristics, the polymeric micelles can serve as potential systems for controlled drug delivery.

Studies on the preparation and controlled release of redox/pH-responsive zwitterionic nanoparticles based on poly-L-glutamic acid and cystamine

Abstract The enhancement of tumor intracellular drug uptake and resistance against nonspecific protein adsorption are essential for an injectable anticancer drug carrier. In the present study, a new type of redox/pH-responsive zwitterionic nanoparticles (NPs) was prepared using poly-L-glutamic acid and cystamine in aqueous solutions under mild conditions. The NPs showed surface charge convertible feature in response to pH change of the solutions. The NPs demonstrated excellent anti nonspecific protein adsorption. In vitro release profiles of the NPs, they showed redox/pH dual sensitivities in vitro release. The effective intracellular delivery behaviors were verified through investigation of cell viability, and confocal laser scanning microscopy observation of HeLa cells after incubation with the DOX-loaded NPs. The NPs were non-cytotoxic and would have potential applications as a drug delivery vehicle for enhancing intracellular uptake of anticancer drugs.