Green synthesis of <i>Piper chaudocanum</i> stem extract mediated silver nanoparticles for colorimetric detection of Hg ²⁺ ions and antibacterial activity

Abstract

A green synthetic approach to synthesize silver nanoparticles (AgNPs) using the stem extract of <i>Piper chaudocanum</i> for highly sensitive colorimetric detection of Hg²⁺ with a low limit of detection of 23 nM and easy colorimetric read-out has been reported. In addition, the biosynthesized AgNPs demonstrated efficient antibacterial activity against <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i> and <i>Staphylococcus aureus</i>. The morphology and structure of the as-synthesized AgNPs were examined using SEM, TEM, EDX, XRD and FT-IR analyses. The XRD and TEM results confirm the formation of AgNPs with an average particle size of 8-12 nm. The TLC, CC and HPLC revealed that four main compounds, pentacosanoic acid (<b>1</b>), piperine (<b>2</b>), <i>β</i>-sitosterol (<b>3</b>), and campesterol glucoside (<b>4</b>), isolated from <i>P. chaudocanum</i> extract act as reducing and stabilizing agents for AgNP formation, and piperine plays a vital role in green synthesis. The chemical structures of these compounds were determined by ESI MS, FTIR, and one- and two-dimensional NMR spectroscopic data analysis. This approach is an efficient, green, cost-effective, eco-friendly and promising technique for synthesizing AgNPs with applications in the colorimetric detection of Hg²⁺ and antibacterial activity.