Advances in Sustained-Release Transdermal Drug Delivery Systems Utilizing Zinc Oxide Nanoparticles

In recent years, sustained-release transdermal drug delivery systems (TDDS) have gained popularity as a viable alternative to regulated and prolonged drug administration because they avoid hepatic first-pass metabolism, increasing bioavailability and lowering systemic side effects. ZnO-NPs can modulate drug permeation through the skin by interacting with the stratum corneum, enabling efficient drug diffusion via transappendageal, transcellular, and intercellular pathways. Their surface charge and nanoscale size contribute to prolonged retention at the application site, ensuring sustained drug release. Zinc oxide nanoparticles (ZnO-NPs) have emerged as potential materials in TDDS due to their distinct features, which include increased catalytic activity and applicability for a variety of biomedical applications. This paper explores the fundamentals of transdermal drug delivery, including skin structure, penetration pathways, and strategies for enhancing drug permeation. It also delves into the mechanisms of sustained release in TDDS, comparing matrix and reservoir systems. Furthermore, the various methods for synthesizing ZnO-NPs, including chemical, vapor transport, hydrothermal, green synthesis, and sol-gel techniques, are discussed. Green-synthesized ZnO-NPs have a variety of biomedical applications, including antibacterial and anticancer properties.