A Nanosensor-Based Prototype Development for Heavy Metal Detection: A Combined Spectroscopic and Theoretical Study

With the advent of technology, nanosensors have proved to be an important tool, which provide a sustainable solution for environmental pollution monitoring. Herein, we report a spectroscopic detection of lead (Pb); one of the toxic heavy metal pollutants with the help of citrate functionalized gold nanoparticles (Au NPs) followed by development of a low-cost prototype device. Self-aggregation of citrate functionalized Au NPs in presence of Pb has been observed spectroscopically. The longitudinal mode of surface plasmon resonance of Au NPs increases as the Pb concentration increases, and consequently, a new peak in the red region of the EM spectrum emerges, which is a clear indication of self-aggregation of NPs. We have used quasi-static approximation based numerical modeling to determine the percentage of aggregation of the AU NPs, which in turn, could be used to determine the amount of Pb ²⁺ ions present in the solution. These key findings have been utilized for the development of low-cost prototype for monitoring Pb pollution in the environment.