Selective picomolar detection of carcinogenic chromium ions using silver nanoparticles capped via biomolecules from flowers of Plumeria obtusa

Abstract

Biocompatible silver nanoparticles (Ag-NPs) were synthesized by employing an eco-friendly approach of green chemistry with flower extract of Plumeria obtusa. Flavonoids are the main phytochemical constituents found in flowers of Plumeria obtusa, out of which rutin is the most abundant and acts as a controller. The synthesized Ag-NPs were studied using UV–vis spectroscopy, X-ray diffractometry (XRD), transmission electron microscopy (TEM), fourier transform infrared (FTIR) analysis, zeta potential and dynamic light scattering (DLS) analysis. The Ag-NPs showed their characteristic surface plasmon resonance (SPR) peak at around 430 nm. This peak depended on various physicochemical parameters such as extract concentration, reaction time, temperature and pH. The formation of the FCC lattice of Ag-NPs with an average particle size of 13 ± 1 nm was confirmed. The zeta potential of −22.7 mV of Ag-NPs indicated their stability in colloidal suspensions. The biosynthesized Ag-NPs were used for developing a sensing method for carcinogenic hexavalent chromium ions (Cr6+) in various aqueous mediums that can be utilized in the diagnosis of any contamination in drinking water or food by cancer-causing Cr6+ ions with a very efficient limit of detection (LoD) of 95 ± 2 pM (recorded at pH ∼ 7.2), which is the lowest reported value for green synthesized nanomaterials and also overcome limitations such as a lack of sensitivity, accuracy, low detection limit and proper explanation. In addition, the antibacterial action of Ag-NPs was investigated against a gram-positive bacterium, Staphylococcus aureus. Thus, based on the results, the Ag-NPs synthesized in this study can be resorted to applications like biosensing and biomedicine.