Monascus pigment‐mediated green synthesis of silver nanoparticles: Catalytic, antioxidant, and antibacterial activity

In order to explore green and efficient methods for the synthesis of nanoparticles, silver nanoparticles (AgNPs) were rapidly synthesized assisted by the Monascus pigments under simulated sunlight. Prepared AgNPs were characterized using various analytical tools such as ultraviolet‐visible (UV–Vis) spectroscopy, Zeta, X‐ray diffraction (XRD), scanning electron microscopy (SEM)–energy dispersive X‐ray (EDX), and Fourier‐transform infrared spectroscopy (FT‐IR). There is an absorption peak at 410 nm in the UV–Vis absorption spectrum, which confirms the formation of AgNPs. XRD results affirmed that the synthesized AgNPs were crystalline in nature and preferentially oriented in (111) plane. The morphology of the nanoparticles was found to be spherical by SEM and particle size analysis study revealed the average particle size to be 18.10 ± 0.30 nm. Zeta potential measurement showed excellent stability of AgNPs with negative values of −9.2 ± 0.66 mV. The FT‐IR study represented involvement of functional groups in AgNPs synthesis. The biosynthesized AgNPs exhibited significant antibacterial activity with zones of inhibition of 9.1, 14.5, and 18.0 mm against Escherichia coli , Pseudomonas aeruginosa , and Staphylococcus aureus , respectively. Through the determination of hydroxyl radical scavenging capacity, ABTS radical scavenging capacity, total reducing power, and total antioxidant capacity, it is proved that the AgNPs have certain antioxidant capacity. In addition, AgNPs could catalyze the degradation of methylene blue, methyl orange, and congo red with a pseudo first‐order rate constants of 0.07998, 0.24666, and 0.11805 min −1 , respectively. Overall studies indicated that the Monascus pigments could be used to prepare AgNPs with potential antibacterial, antioxidant, and extraordinary catalytic activity. It can be used in biomedical applications, commercial food packaging, pathogen mitigation, and industrial waste water management.