GREEN SYNTHESIZED SILVER NANOPARTICLES: SURFACE PLASMON RESONANCE ALLIED APPLICATIONS

Abstract

For this study, biocompatible silver nanoparticles (Ag-NPs) were successfully synthesized via employing an environment friendly green approach by usage of flower extract of Plumeria obtusa. For studying the attributes of synthesized Ag-NPs, techniques such as UV-vis spectroscopy, X-Ray diffractometry (XRD), transmission electron microscopy (TEM), zeta potential and dynamic light scattering (DLS) analysis were used. The characteristic surface plasmon resonance (SPR) peak of Ag-NPs was observed around 430 nm. This peak was found to be dependent on different physicochemical parameters like amount of flower extract, reaction time, temperature and pH value. The crystal structure was studied from XRD pattern which confirmed the formation of FCC lattice with a crystallite size of 20 nm and particle size of 14 nm. TEM analysis also showed that spherical Ag-NPs of mean diameter 13 nm were formed. The stability of colloidal Ag-NPs was studied using zeta potential analysis, whose value came out to be 13 nm. The synthesized Ag-NPs were used in developing a sensing mechanism for a very harmful carcinogen, hexavalent chromium (Cr6+) and the same was tested in three different aqueous mediums. The limit of detection (LoD) came out to be 95 ± 2 pM, which is lowest reported value of LoD for a biosynthesized nanomaterials and thus, can be efficiently applied in diagnosing any contamination by cancer-causing Cr6+, in drinking water or food. Further, the enhancement in anti-bacterial action of Ag-NPs over AgNO3 was also investigated, against a gram-positive bacterium, S. Aureus. The inhibition zone came out to be much wider (10.8 mm) than that of AgNO3 (7.7 mm) or plant extract (6.7 mm). Thus, the Ag NPs synthesized in this project are non-toxic, cost-efficient and can be utilized in a variety of applications like biosensing and biomedicine.