Amorphous selenium nanoparticles: synthesis strategies and multifunctional applications

Selenium is a vital trace element involved in many biological processes. In recent years, amorphous selenium nanoparticles (a-SeNPs) have gained considerable interest for their better biocompatibility, reduced toxicity, and better functionality than the crystalline form. Because of these properties, a-SeNPs are being increasingly investigated for various applications. a-SeNPs can be prepared by chemical, hydrothermal, microwave-assisted, and biological synthesis, with the latter providing better stability and biocompatibility. Their size, shape, and amorphous nature have a profound impact on their physico-chemical and biological properties. This review discusses different synthesis strategies and highlights the multifunctional applications of a-SeNPs, including antioxidant, antibacterial, anticancer, bioimaging, biosensing, agricultural, and photocatalytic applications along with future perspectives in this field.