Antimicrobial, radical scavenging, and dye degradation potential of nontoxic biogenic silver nanoparticles using Cassia fistula pods

Synthesis of metallic nanoparticles via green approach holds great potential in diverse fields of biotechnology and medicine with special mention to silver nanoparticles (AgNPs) which undoubtedly display antimicrobial, radical scavenging, and dye degradation properties. Currently, there is a need to explore more cost-effective and efficient methods to synthesize AgNPs. In this study, we have synthesized biogenic AgNPs using an aqueous extract of a flowering plant of the legume family, Fabaceae, subfamily Caesalpiniaceae,Cassia fistula, which is also well known for its medicinal values. Spectroscopically and physicochemically characterized AgNPs were evaluated for their cytocompatibility, antimicrobial effects, antioxidant and catalytic activity to establish their potential for various biomedical applications. DLS studies revealed their size similar to 237 nm with the surface charge of similar to - 30 mV. The results of the zone of inhibition and MIC assays showed the superiority of the activity of these particles over the pod extract. Catalytic reduction of toxic p-nitrophenol to benign p-aminophenol as well as degradation of hazardous industrial dyes (methyl orange and methylene blue) advocated their potential as environmental toxicant eradicators. Besides, these biogenic AgNPs displayed profound antibiofilm effects in static microtiter plates. Altogether, the results of various bioassays using these biogenic nanoparticles demonstrate their immense potential as antimicrobial, antioxidant, and antibiofilm agents.