Hyperbranched polyglycerol-grafted WO_x nanowires: Synthesis, characterization, functionalization and as effective drug targeted delivery vehicle

Tungsten oxide (WOx) is an important n-type semiconductor, which has attracted wide attention in the fields of gas sensing materials, photocatalysis, photoluminescence and electrochemistry due to its excellent electro-optical properties. However, the application potential of WOx-based nanomaterials in biomedicine has been neglected. In this paper, we firstly synthesized tungsten oxide nanowires (WOx) by one-step method using tungsten chloride and triethylene glycol as raw materials, and reported an effective surface engineering strategy for polyglycerol-functionalized tungsten oxide nanowires (WOx-PG) to enhance their colloidal stability, biocompatibility, and selective toxicity to specific cancer cells in dispersion media. The WOx-PG was further derivatized and covalently combined with FA (WOx-PG-FA) as a drug targeting vector to deliver doxorubicin (DOX) to cancer cells. Compared with WOx NWs, WOx-PG exhibits smaller size (30 - 90 nm), more uniform distribution, better solubility and biocompatibility. The hemolysis rate of PG-modified WOx NWs was significantly reduced, being only 1.35 % at 200 mu g/ml. The in vitro drug release percentage of WOx-PG-FA/DOX reached 80.78 % within 48 h at pH 5.2. In vitro toxicity assays and confocal laser scanning microscope (CLSM) results indicated that PG-functionalized WOx NWs were not cytotoxic, and WOx PG-FA/DOX had highly selective cytotoxicity on HeLa cells. These results indicate that WOx -PG-FA is a potential drug carrier for effective targeting of cancer therapy.