The aim of this study is to investigate a new strategy of combined application of ZnO/PEG nanospheres with anticancer drug of doxorubicin (DOX) in photodynamic therapy (PDT). We were able to fabricate ZnO/PEG nanospheres as the drug carrier of DOX in drug delivery system. The combination of DOX-ZnO/PEG nanocomposites induced the remarkable improvement in the anti-tumor activity, which has been demonstrated by antibacterial activity, drug release and DNA cleavage study. Furthermore, the possible mechanism was explored by optical spectroscopic studies and EPR - spin trapping technique. It was noted that the photodynamic activity of the non-cytotoxic DOX loaded ZnO/PEG nanocomposite could considerably increase cancer cell injury mediated by reactive oxygen species (ROS) under UV irradiation. In our observations demonstrated that ZnO/PEG nanosphere could obviously increase the intracellular concentration of DOX and enhance its potential anti-tumor efficiency, indicating that ZnO/PEG nanosphere could act as an efficient drug delivery carrier importing DOX into target cancer cells. Nearly 91% of loaded drug was released within 26 h of incubation of conjugates in vitro in an acidic environment. It suggests that there is an efficient drug release of DOX from DOX-ZnO/PEG nanocomposite. DOX loaded on ZnO/PEG nanomaterials showed antibacterial activity was more pronounced with Gram-positive than Gram-negative bacteria under visible light. DOX-ZnO/PEG nanocomposites were effective against HeLa cell lines under in vitro condition and photocleavage of DNA. This result indicated that ZnO/PEG nanomaterials can be used as a nanocarrier for drug delivery system for PDT.
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