Functional Zinc Oxide Nanocrystals for Photodynamic Therapy: A Brief Review

Abstract

The emergence of cancer nanomedicine is the result of fruitful advances in the fields of nanotechnology,  bioimaging, formulation development, and molecular biotechnology. Zinc oxide nanoparticles (ZnO NPs) are able to accumulate specifically within a tumor region thanks to the enhanced permeation and retention effects. However, the photodynamic therapy (PDT) shows limited tissue penetration owing to the small penetration depth of ultraviolet light  used to excite the NPs. Thus, PDT can be efficiently exploited for superficial tumors or with optical waveguide irradiation in the case of deeper but accessible cancer tissues. The role of ZnO NPs in these multifunction nanoplatforms and biomedical applications as well as the recently emerged PDT are discussed.