Phytomediated generation of Ag, CuO and Ag-Cu nanoparticles for dimethoate sensing

Biological and environment safety concerns due to employment of metal nanoparticles (NPs) in various sectors have directed the focus of researchers on the biogenic route of nanosynthesis. Here we report a simple and environment friendly approach for the synthesis of Ag, CuO and Ag-Cu bimetallic nanoparticles using stem extract of Amaranthus tricolor L. (agro waste) containing polyphenolic biomolecules. The fabricated method does not require any special conditions or toxic chemical reagents and favour the facile process for synthesis of the said nanoparticles as a greener alternative. The synthesized nanoparticles were characterized by absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta (xi) potential measurement, X-ray photoelectron spectroscopy (XPS), infra red (IR) and Raman spectroscopy. The developed nanoparticles were found useful for the optical sensing of dimethoate, an organophosphorus used as a common pesticide in the concentration range 3-20 mu M. The chemical sensing of the analyte using the nanoparticle substrate is also supported by Raman spectral evidences. Presence of abundant hotspots in NPs results in an enhanced electromagnetic field after interaction with light which makes it suitable to study its response to the analyte in the Raman spectral mode.