Colorimetric methods using gold nanoparticles for forensic investigations.

Gold nanoparticles (GNPs) are increasingly employed in biosensing and forensic applications due to its unique optical properties, especially surface plasmon resonance (SPR). This property enables GNPs to undergo significant color changes in response to alterations in particle size, shape, and aggregation, making them ideal for sensitive colorimetric assays. These assays can detect analytes such as heavy metals (e.g., mercury, lead) and biomolecules without requiring complex instrumentation. The biocompatibility and functionalization versatility of GNPs enhance its application in forensic science, particularly for detecting toxic metals in biological samples. This review paper provides details regarding colorimetric methods using GNPs for forensic investigations using aggregation and ant aggregation-based detection of analytes using several ligands tagged with GNPs. This review is also focused on forensic toxicology, drug analysis, DNA profiling, latent fingerprint visualization, pesticide residue detection, and identification of explosive and gunshot residues. Forensic analysis of pesticides, such as organophosphates, carbamates, and pyrethroids, is effectively achieved using GNP-based colorimetric sensors, which detect compounds through visible color changes. Overall, the review emphasizes the critical role of GNP-assisted colorimetric methods in modern forensic investigations and its potential to revolutionize field-based analytical approaches.