ZnO nanostructures based biosensors for cancer and infectious disease applications: Perspectives, prospects and promises

ZnO nanostructures have attracted great attention from researchers due to their fascinating properties that include high surface-area, better crystallinity, and improved optical and electrical properties. These intriguing properties make them highly desirable for various applications including biosensors, tissue engineering, drug delivery system and cancer diagnostics. Various interesting techniques have been explored for the successful fabrication of ZnO nanostructures with desirable morphologies. Depending on the mode of synthesis, ZnO nanostructures synthesis is classified into two main categories, dry and wet chemical synthesis. Both the methods have their advantages and disadvantages respectively. Various protocols have been developed for functionalization of these nanostructures, to modify their surfaces. Different techniques for the effective bio-functionalization of one-dimensional (1D) ZnO nanostructures are presented in this review. Organic functionalities of ZnO nanobelts enhance the optoelectronic and electrical properties. Biomolecules such as human serum albumin, bovine serum albumin, angiotensin II and DNA molecules have been effectively immobilized by modifying the surface of 1D ZnO nanostructures. ZnO nanostructures are increasingly being studied for advanced biological applications such as cancer, infectious diseases, cellular biocompatibility, fluorescence detection, mammalian cell biosafety, biosensor applications, and adhesion. This review focuses on and presents a summative view on ZnO nanostructures with special emphasis on its applications in the pursuit of improving human life.