Factors that Affect Pickering Emulsions Stabilized by Graphene Oxide

Stable Pickering emulsions were prepared using only graphene oxide (GO) as a stabilizer, and the effects of the type of oil, the sonication time, the GO concentration, the oil/water ratio, and the pH value on the stability, type, and morphology of these emulsions were investigated. In addition, the effects of salt and the extent of GO reduction on emulsion formation and stability were studied and discussed. The average droplet size decreased with sonication time and with GO concentration, and the emulsions tended to achieve good stability at intermediate oil/water ratios and at low pH values. In all solvents, the emulsions were of the oil-in-water type, but interestingly, some water-in-oil-in-water (w/o/w) multiple emulsion droplets were also observed with low GO concentrations, low pH values, high oil/water ratios, high salt concentrations, or moderately reduced GO in the benzyl chloride–water system. A Pickering emulsion stabilized by Ag/GO was also prepared, and its catalytic performance for the reduction of 4-nitrophenol was investigated. This research paves the way for the fabrication of graphene-based functional materials with novel nanostructures and microstructures

A Light-Responsive Release Platform by Controlling the Wetting Behavior of Hydrophobic Surface

Controlled release system based on mesoporous silica (MS) nanomaterials has drawn great attention over the past decades due to its potential biomedical applications. Herein, a light-responsive release system based on MS nanoparticles was achieved by adjusting the wetting of the MS surface. At the starting stage, the surface of MS modified with optimal ratio of spiropyran to fluorinated silane (MS-FSP) was protected from being wetted by water, successfully inhibiting the release of model cargo molecules, fluorescein disodium (FD). Upon irradiation with 365 nm UV light, the conformational conversion of spiropyran from a “closed” state to an “open” state caused the surface to be wetted, leading to the release of FD from the pores. The further <i>in vitro</i> studies demonstrated the system loaded with anticancer drug camptothecin (CPT) could be effectively controlled to release the drug by UV light stimuli to enhance cytotoxicity for EA.hy926 cells and HeLa cells. This wettability-determined smart release platform could be triggered by remote stimuli, which might hold promise in the applications of drug delivery and cancer therapy