In current times, environmental pollution due to cause of heavy metal ions has reached one of the most demanding challenges on the earth. Among all heavy metals, lead ions are the most dangerous metal ions even at low concentrations. According to the WHO, the allowable level of Pb2+ in drinking water is less than 10 nM. Therefore, it’s very crucial to detect Pb2+ ions selectively. Here, I have introduced a facile green tactic for the synthesis of gold nanoparticles for colorimetric recognition of Pb2+ ions. Various spectroscopic techniques, such as UV-Visible, FTIR, TEM, EDX, XRD, SAED, AFM, DLS, FE-SEM, XPS, and Zeta Potential, were applied for characterization of the nanoparticles. The AuNPs exhibited a SPR peak at 542 nm, having a diameter of 25.26 nm with varying morphologies like spherical, triangular, truncated triangles and decahedral. It shows very fast, notable colorimetric identification of Pb2+ ions within 9 seconds with the naked eye. The synthesised probe displayed its maximum stability and sensing activity at a wide range of pH from 3.3 to 7.9, which was one of the most significant aspects of this research work. In addition, the probe exhibited a very low limit of detection (LOD =76.14 fM) by changing colour from red to violet with a prominent red shift of the peak from 542 nm to 630 nm. Moreover, here, no metal cations and anions interfere. Besides, our synthesized probe was useful in real sample analysis, and the results demonstrated that it fitted large-scale recovery with good precision.

Dr. Manjushree Bhattacharyya has completed Ph.D. work in Chemistry as a Research Fellow (02/01/2019 - 02/01/2024) using the scheme of UGC- NET (JRF), All India Rank (AIR)-58. She has two notable publications and three preprint articles. She did her Master's (rank holder, 3rd rank) in Vidyasagar University with specialization of Organic Chemistry. She has carried out Bachelor of Science (B.Sc.) in Chemistry (Honours) with silver medal award. She has also qualified various national exam like JAM, Joint CSIR-UGC NET, GATE. Her major research interest is the development of nanoparticles-based sensors for detection of toxic metal ions through colorimetric approach.