Corn Silk (Stigma Maydis) Extract-mediated Silver Nanoparticles: Promising Antimicrobial, Antioxidant, Catalytic Applications, and DNA Protection

The production of metal nanoparticles (NPs) has risen in importance in recent decades. The green synthesis of silver NPs (AgNPs) occupies a prime position in this development, and AgNPs have been widely used in various biomedical, industrial, and therapeutic applications. In this study, research was performed using corn silk (CS) for the synthesis of AgNPs. The green-synthesized CS-AgNPs were analyzed using various spectroscopy methods. The metal NPs exhibited intense surface plasmon resonance peaks at different wavelengths with a specific peak at 461 nm, which confirmed the synthesis of AgNPs. Fourier-transform infrared spectroscopy was performed to confirm the participation of phytoactive biocomponents of CS extract in the reduction and stabilization of CS-AgNPs. Scanning electron microscopy of CS-AgNPs revealed that the NPs had an irregular, roughly spherical shape. The size of CS-AgNPs was evaluated via dynamic light scattering, which showed that the CS-AgNPs were polydisperse in nature with an average size of 3.6–58.6 nm and an average mean size of 53 nm. The zeta potential of CS-AgNPs was –27.5 mV, indicating that CS-AgNPs are highly stable in colloidal form with a high negative potential. CS-AgNPs exhibited excellent and moderate antimicrobial activity against Gram-positive and Gram-negative bacteria. CS-AgNPs had excellent antioxidant activity using the DPPH method compared with the nitric oxide assay and also could perform photocatalytic degradation of cotton blue dye. Furthermore, CS-AgNPs protected plasmid DNA at 95 °C from heat-based denaturation. Thus, green-synthesized CS-AgNPs had potential for prolific biomedical, industrial, and molecular biology applications of economic importance.