Harnessing Nature's Chemistry: Eco-friendly fabrication of copper, iron and silver nanoparticles for an environmental toxin biosensor

This study presents a comparative analysis of the green synthesis of copper (Cu), iron (Fe), and silver (Ag) nanoparticles (NPs) using an aqueous leaf extract of Solanum sisymbriifolium as both a reducing and capping agent. The synthesized nanoparticles were characterized using several techniques. Ultraviolet–Visible (UV–Vis) spectroscopy confirmed the formation of the NPs by observing characteristic surface plasmon resonance (SPR) peaks. Fourier-transform infrared (FTIR) spectroscopy identified the functional groups in the leaf extract responsible for the reduction and stabilization of the NPs. The synthesized Cu, Fe, and Ag NPs were then evaluated for their biosensing capabilities. The results demonstrated that UV–Vis spectroscopy revealed SPR peaks at 257 nm for CuNPs and at 450 nm for both FeNPs and AgNPs, indicating successful nanoparticle formation. The presence of bioactive functional groups like phenolics, amines, and esters in nanoparticle capping was confirmed by the FTIR spectra. Biosensing assays demonstrated clear colorimetric responses for all nanoparticles upon exposure to heavy metal ions, with AgNPs exhibiting the highest sensitivity and the clearest visual distinction. FeNPs displayed selective enhancement towards ferric and lead ions, while CuNPs showed uniform responses across all tested ions. All three types of nanoparticles exhibited promising biosensing activities on heavy metal salts. The Ag NPs showed the highest sensitivity and stability, followed by Cu NPs and then Fe NPs. This study highlights the potential of using Solanum sisymbriifolium for the eco-friendly synthesis of various metal nanoparticles and their application in developing cost-effective and efficient biosensors.