Synthesis of Protium serratum fruit extract stabilized silver nanoparticles for the detection of iodine in solution and vapour phase

Abstract

This study presents an eco-friendly benign method for synthesizing silver nanoparticles (AgNPs) using Protium serratum (Indian red pear, IRP) fruit extract as a reducing and stabilizing agent, with AgNO₃ serving as the metal precursor. The synthesis was completed in 60 min at 60 °C, demonstrating the potential for scalability for large-scale production. GC–MS and FT-IR spectroscopies were used to analyse the fruit extract, while UV–Vis spectroscopy, DLS, XRD, AFM, and TEM were used to characterize the synthesized IRP-AgNPs. The study confirmed the high crystallinity with an average crystallite size of 22 nm (XRD) and the particle size of 18.5 nm (TEM). The binding of phytochemicals to AgNPs was validated by Density Functional Theory (DFT) simulations. IRP-AgNPs were employed to quantify iodine in aqueous solutions using UV–Vis spectroscopy. The limits of linearity (LOL) and detection (LOD) have been found to be 0.241 mM and 0.032 mM, respectively. Additionally, paper-based test strips containing IRP-AgNPs have been fabricated to enable rapid visual iodine detection within 1 s through color change following exposure of the strips to iodine vapor. Furthermore, the solution-based method has successfully been used to detect iodine in spiked human blood serum, demonstrating its applicability in physiological environments and its potential utility in diagnosing iodine imbalance. To advancing sustainable nanotechnology, this green synthesis method emphasizes how natural resources can be used to create quick and affordable detection tools.