Selenium microparticles decorated graphene oxide via green synthesis using Psidium guajava leaves: preparation, characterization, and biological activities

An environmentally friendly method was used to synthesize selenium microparticles (SeMPs) by applying Psidium guajava leaf extracts as a reducing agent. In addition, in this study, SeMPs were combined with graphene oxide (Se/GO) via an ex situ method. The results of the phytochemical analysis of the Psidium guajava leaves revealed the presence of flavonoids, polyphenols, triterpenoids, and ascorbic acid. In addition, the results indicated that the SeMPs were spherical and uniformly distributed on graphene oxide (GO) sheets with an average diameter of about 475 nm. Moreover, the antioxidant activity was investigated with two free radical scavenging methods 2-diphenyl-1-picrylhydrazyl and 2,20-azino-bis(3ethylbenzothiazoline-6-sulfonic acid) with yields of 63.34 and 90.9%, respectively. Additionally, the antibacterial performance of the resulting material, which showed a great inhibition performance against the Gram-positive strains of Staphylococcus aureus, Bacillus subtilis, and Limosilactobacillus fermentum, Gram-negative ones of Escherichia coli and Salmonella enterica, and the fungi strain of Candida albicanas, was investigated. Moreover, the anticancer activity was evaluated towards three cell lines, including liver cancer cells, lung cancer cells, and human embryonic kidney cells. The results revealed that the anticancer performance of the material achieved 90% with a Se/GO concentration of 256 mg mL(-1). The anti-diabetic ability of the material toward the enzyme a-glucosides also showed high results with an inhibiting percentage of 100%, reaffirming the promising potential of the Se/GO materials in medical applications.