Greener production of silver nanoparticles: a sensitive nanodrop spectrophotometric determination of biothiols

Abstract: In the present work, we report an environmentally friendly, low cost, rapid, biocompatible, and greener approach for the production of silver nanoparticles (AgNPs) via the latex extract of Ficus benghalensis. The latex extract contains bioactive phytochemical constituents that can reduce and stabilize the silver salt in reacting solution. The resulting AgNPs were characterized. The surface plasmon resonance (SPR) was measured at wavelength, λmax 410 nm. High resolution transmission electron microscopy (HR-TEM) and scanning electron microscopy of AgNPs revealed the spherical shape with mean particle size was approximately 14 ± 0.69 nm. AgNPs Capped with latex show a strong affinity to the thiol group of biothiols (L-cysteine and glutathione). Upon the addition of biothiols, the absorbance of AgNPs decreased with a new SPR peak appeared at a higher wavelength, suggesting that the AgNPs were conjugate to biothiols with rapid aggregation. Owing to this interaction, a nanodrop spectrophotometer (NDS) was used as an advanced, fast response, and high-efficiency colorimetric assay for the selective determination of L-cysteine (Cys) and glutathione (GSH). A good linear relationship was found over the range of 0.2–1.0 ppm of biothiols. The obtained detection limits (LOD) were 0.17 and 0.18 ppm for the Cys and GSH, respectively. The applicability of the proposed NDS procedure has been validated by determining Cys and GSH in biological samples with satisfactory recovery results. Graphic abstract: [Figure not available: see fulltext.]