Multifunctional ZnO nanostructures: a next generation nanomedicine for cancer therapy, targeted drug delivery, bioimaging, and tissue regeneration

Zinc oxide nanostructures (ZnO NSs) are one of the most versatile and promising metal oxides having significant importance in biomedical fields, especially for therapeutic and diagnostic purposes. ZnO possesses unique physio-chemical and biological properties such as photo-chemical stability, corrosion resistance, mechanical properties, biocompatibility, higher targeting capability, and ROS-triggered cytotoxicity. These ZnO NSs have enhanced potential for various biomedical applications such as cancer therapy, drug delivery, bioimaging, tissue engineering, etc. Furthermore, ZnO possesses excellent luminescent properties that make it useful for bioimaging and image-guided targeted drug delivery, thereby reducing the unwanted side effects of chemotherapeutic agents. Besides, these characteristics, enhanced permeability and retention effect, electrostatic interaction, ROS production, and pH-dependent dissolution of ZnO also make it potential aspirant as therapeutic that are suggested as key parameters for cytotoxic and cell death mechanismsviaapoptosis, autophagy, and mitophagy mechanisms. Here, the recent progress and advances of ZnO NSs in bioimaging, drug delivery, and tissue engineering are discussed along with the advantages, limitations, and future advancement for biological applications.