Multiscale Simulation of Colorimetric Response of Silver Nanoparticles to Lead Ion Adsorption and Aggregation

Résumé fourni par la source

Silver nanoparticles (AgNPs) exhibit distinct color changes upon interaction with heavy metal ions such as lead (Pb2+), forming the basis of simple and sensitive colorimetric sensors. These sensors are increasingly relevant in environmental monitoring and public health, as Pb contamination remains a persistent threat even at trace levels. The observed color transitions arise from a combination of size-dependent optical effects, nanoparticle aggregation, and surface chemical modifications. In this work, we present a computational framework capable of reproducing these spectral and perceptual changes using physically grounded models that are computationally efficient and executable on standard hardware. The simulation pipeline integrates three main components: Mie theory for isolated nanoparticle scattering, coupled-dipole modeling for aggregation-induced plasmonic coupling, and parametric adjustments of the silver dielectric function to represent Pb adsorption and associated electron density changes. Extinction spectra obtained from these calculations are converted to visible sRGB colors under CIE D65 illumination to provide perceptual visualization. Simulated results reproduce the experimentally observed yellow-orange-brown color sequence as a function of particle size, degree of aggregation, and surface interaction, providing quantitative insight into the mechanisms driving AgNP-based Pb detection. This framework offers a practical predictive tool for designing nanoparticle-based colorimetric sensors without the need for computationally intensive quantum chemical calculations.

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