Abstract
A key aspect of forensic investigations involves identifying and detecting body fluid stains, preserving them for subsequent DNA extraction, and linking criminal activity with the right perpetrators. The body fluid stains frequently encountered at a crime scene are blood, urine, saliva, etc. The process of stain identification might provide challenges due to the limitations of current techniques, which are primarily focused on certain body fluids and often involve destructive procedures. Chemical reagents such as luminol and DMAC are mostly used for the detection of body fluids at crime scenes. However, these chemicals have limitations like short shelf life, lower specificity, and sensitivity. To address these concerns, alternate materials such as silver and gold nanoparticles were prepared from extracts of Sclerocarya. birrea (S. birrea) and Moringa. oleifera (M. oleifera) stems. These materials were used in this study to provide a universal, confirmatory, and non-destructive technique capable of identifying and distinguishing various bodily fluids. S. birrea and M. oleifera are abundant in phytochemicals such as alkaloids, polyphenols, and flavonoids. These compounds act as both reducing and stabilising agents, facilitating the nanoparticle synthesis process. Silver and gold nanoparticles were used to enhance the performance of Luminol and 4-dimethylaminocinnamaldehyde (DMAC) to be more sensitive and specific to a specific fluid stain. Promising results were discovered from this part of the thesis. AgNPs and AuNPs were characterised using techniques such as X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Zetasizer analysis, Spectrophotometer, high-resolution scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (HRSEM-EDS), and ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and transmission electron microscopy (TEM). The XRD analysis revealed that both gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) exhibited a face-centred cubic (FCC) crystalline structure. The TEM results revealed the diverse shapes and sizes of AgNPs and AuNPs, including spherical, oval, anisotropic, triangular, octahedral, rod-like structures, and hexagonal shapes. The EDS spectra revealed intense peaks accounting for 80-96% content of silver and gold corresponding to AgNPs and AuNPs. Zeta potential studies showed that gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) are negatively ...