Upconversion nanoparticles possess unique optical properties, making them attractive for applications in bioimaging, sensing, and therapy. However, their potential toxicity remains a significant concern. This review aims to provide a thorough analysis of the toxicity connected with upconversion nanoparticles. It examines various aspects, including

Zinc oxide is a substance renowned for its remarkable strength to safeguard delicate skin. This calming component has long been employed in a variety of skincare products, from sunscreens to diaper rash creams, due to its outstanding protective properties. Establishing a physical barrier on the skin's top layer, zinc oxide effectively reflects ha