Enhanced photodynamic therapy/photothermo therapy for nasopharyngeal carcinoma via a tumour microenvironment-responsive self-oxygenated drug delivery system

The hypoxic nature of tumours limits the efficiency of oxygen-dependent photodynamic therapy (PDT). Hence, in this study, indocyanine green (ICG)-loaded lipid-coated zinc peroxide (ZnO(2)) nanoparticles (ZnO(2)@Lip-ICG) was constructed to realize tumour microenvironment (TME)-responsive self-oxygen supply. Near infrared light irradiation (808 nm), the lipid outer layer of ICG acquires sufficient energy to produce heat, thereby elevating the localised temperature, which results in accelerated ZnO(2) release and apoptosis of tumour cells. The ZnO(2) rapidly generates O(2) in the TME (pH 6.5), which alleviates tumour hypoxia and then enhances the PDT effect of ICG. These results demonstrate that ZnO(2)@Lip-ICG NPs display good oxygen self-supported properties and outstanding PDT/PTT characteristics, and thus, achieve good tumour proliferation suppression.