Electroanalytical performance of PVP stabilized silver nanoparticles green synthesized via centella asiatica extract toward non enzymatic detection of glucose

Abstract

Green synthesis of polyvinylpyrrolidone (PVP) stabilized silver nanoparticles (AgNPs) was carried out using aqueous leaf extract of Centella asiatica (L.) Urban as a bioreducing and capping agent. Phytochemical screening confirmed the presence of flavonoids, phenolics, alkaloids, saponins, and terpenoids, which contributed to Ag⁺ ion reduction and nanoparticle surface stabilization. Optimal synthesis conditions were established at 1.5 mM AgNO₃, 40 mL AgNO₃ volume, 3% w/v PVP, and 48 h incubation time. UV-Vis spectroscopy confirmed nanoparticle formation via a surface plasmon resonance (SPR) band at λmax = 425.5 nm. FTIR analysis revealed PVP coordination through C O (1658.78 cm⁻¹) and C–N (1168.86 cm⁻¹) functional groups. Particle size analysis showed a mean hydrodynamic diameter of 113.41 nm with a polydispersity index (PDI) of 0.171, indicating a homogeneous colloidal distribution. XRD confirmed the face centered cubic (FCC) crystalline structure of metallic Ag⁰ with an average crystallite size of 18.76 nm and crystallinity 38.72%, while SEM revealed predominantly spherical morphology. The synthesized AgNPs and AgNPs-PVP were applied to modify carbon paste working electrodes and evaluated via cyclic voltammetry across anhydrous glucose concentrations of 1–10 mM. Both modified electrodes demonstrated significantly higher current responses than the unmodified electrode. Validation using real blood serum samples showed that the AgNPs-PVP modified electrode measured glucose at 78 mg/dL, closely matching the standard GOD-PAP method result of 79 mg/dL, with a relative error of only 1.27%. These findings confirm that Centella asiatica leaf extract is an effective eco-friendly bioreductant for producing stable AgNPs-PVP with strong potential as a simple, rapid, and cost effective electrochemical sensor for blood glucose determination.

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