The exploitation of rice husk biomass for the bio-inspired synthesis of gold nanoparticles as a multifunctional material for various biological and photocatalytic applications.

We report an efficient and facile approach to biosynthesis of gold nanoparticles (AuNPs) using the extract of an agro-waste rice husk generated from rice production. The biosynthesized NPs produced were characterized by UV-Visible absorption, TEM, XRD, EDX, and FTIR methods. The impact of temperature and pH on the stability of the synthesized AuNPs was also studied. The TEM imaging revealed the formation of monodispersed spherical NPs with an average size of ~ 15 nm. The absorption spectrum of AuNPs demonstrated the formation of Surface Plasmon Resonance (SPR) peak at 530 nm. The XRD pattern suggested the formation of face-centered cubic (FCC) lattice structure of AuNPs. The FTIR analysis displayed characteristic peaks related to various phytochemicals in the plant extract responsible for reducing and stabilizing NPs. In addition, AuNPs showed thermal stability when subjected to various temperature scales. The AuNPs exhibited an efficiency against the pathogenic bacteria Staphylococcus aureus and pathogenic fungi Candida albicans. The AuNPs 18.5% DPPH free scavenging activity, indicating the antioxidant potential for AuNPs. In addition, the AuNPs showed anticancer activity against the colorectal adenocarcinoma carcinoma cell line. Furthermore, AuNPs displayed significant enhancement in photocatalytic degradation of Methylene Blue and 4-Nitrophenol dyes. The results obtained reveal the possible usage of AuNPs produced using rice husk in several biomedical applications.