Sustainable PVP-capped gold nanoparticles synthesis “green” chemistry plasma-liquid method and colorimetric activity for water pollutant chromium ion (Cr(VI))

Abstract

Gold nanoparticles (AuNPs) are widely utilized in colorimetric sensing, leveraging their optical characteristics to identify variables through noticeable color alterations. Polymer (PVP)-functionalized gold nanoparticles were successfully prepared in a single step by the induced plasma-under-liquid process. We will evaluate plasma-liquid method synthesis by GREEnness calculator. The effects of different concentrations of PVP on the synthesis and characteristics of the AuNPs, such as size distributions, hydrodynamic diameters, polydispersity indices (PDI), absorbance intensity, and LSPR, were characterized and investigated. The as-synthesized PVP-AuNPs were characterized by SEM, DLS, and UV–visible spectroscopy. Spherical AuNPs were generated, displaying a maximal absorption peak at around 530–560 nm and a size range of 30–50 nm, which can be adjustable depending on the initial concentration precursor and capping agent used in the synthesis process. Polyvinylpyrrolidone-coated gold nanoparticles (PVP-AuNPs) were employed as a colorimetric probe for the quick, easy, sensitive, and selective measurement of chromium ion (Cr(VI)) contamination in water. In fact, chromium ion (Cr(VI)) caused the colloidal solution’s hue to change from red to blue by forcing PVP-AuNPs to aggregate with PVP on the surface of AuNPs. It was established that size and polydispersity affect the colorimetric properties of functionalized nanoparticles during colorimetric detection of the analyte. Optimizing the experimental parameters (volume/concentration AuNPs, the dependence of limit of quantification (LOQ), limit of detection (LOD) at temperature) revealed a good linear connection between the concentration of chromium ion (Cr(VI)) and the absorption ratio (A₆₉₀/A_530-560) in the range of 0.1–3.0 µM with a detection Limit of 0.072–0.1 µM. The selectivity of the developed colorimetric nanoprobe was evaluated by testing its response to various common heavy metal ions. The analytical GREEnness calculator, a comprehensive assessment approach to this method, uses 12 principles of green analytical chemistry which transformed into a unified 0–1 scale. Potential use of methods in quality control laboratories is valuable for the pharmaceutical sector.