One-pot, aqueous synthesis of multifunctional biogenic Ag NPs for efficient 4-NP reduction, Hg2+ detection, bactericidal, and antioxidant activities

We have developed a green and environmentally friendly approach for the synthesis of silver nanoparticles (Ag NPs) using Pithecellobium dulce seeds (PDS) extract via a simple route and characterized by several techniques. Ag NPs have an average particle size is 8 nm and used as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 3 min of reaction. Ag NPs could be easily recovered and reused five times without significant loss in its catalytic activity. The synthesized Ag NPs were investigated for optical sensing of various metal ions in aqueous solutions by monitoring their surface plasmon resonance (SPR), results showed that the selective response to mercury (Hg2+) ions. Ag NPs exhibited significant antibacterial activity against several microorganisms including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis by a paper-disk method. The synthesized Ag NPs also exhibited virtuous antioxidant activity.