Towards sustainable and selective detection of lead Ions: Selaginella bryopteris assisted green synthesis of gold nanoparticles with tunable properties

The detection of highly toxic Pb2+ ions has propelled the exploration of green chemistry as an environmentally benign approach to synthesizing gold nanoparticles (AuNPs) for sensing applications. Herein, a simple green synthesis method is presented without utilizing optimization conditions for stable and well-disperse AuNPs for Pb2+ ions colorimetric sensing. The Selaginella bryopteris plant (SBp) extract as a reducing, capping, stabilizing, and chelating agent was employed in the volume ratio-controlled synthesis of AuNPs. The AuNPs were characterized using UV-Vis, XRD, FTIR, and TEM analysis. The results revealed polycrystalline AuNPs with SPR, particle size, and crystallite size-tunable by SBp extract. The AuNPs bound by Pb2+ ions showed immediate aggregation and excellent selectivity compared to other metal ions (Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Hg2+, Mg2+, Mn2+, Ni2+, Zn2+, and Na+). A linear colorimetric response of AuNPs was observed in the 10–60 µM Pb2+ ions concentration range and the R2 obtained was 0.99654 with LoD of 0.24 µM. The best detection of Pb2+ ions was achieved in a pH range from 3 to 9. The study suggests that the SBp extract-tunable AuNPs synthesis could be used as a sustainable and simple approach for Pb2+ ions detection in the natural environment. [Display omitted] •Simple green synthesis with Selaginella bryopteris plant extract as reducing, capping, stabilizing, and chelating agent.•Very stable and different-colored gold nanoparticles are synthesized without optimizing the synthesis conditions.•Surface plasmon resonance (SPR), nanoparticle size, and crystallite size-tunable biosynthesis method were developed.•Gold nanoparticles demonstrated excellent and rapid selectivity for lead ions (Pb2 +) across a wide pH range.