The use of nanoparticles in the analysis of species and properties of some biological fluids and investigation of effectiveness of raman spectroscopy in illumination of forensic cases

One of the important aspects of forensic science is obtaining evidence accurately from the crime scene. These can be highly diverse, especially bodily fluids (blood, sweat, urine, semen, saliva, etc.) which constitute the most crucial pieces of evidence in forensic investigations. Determining whether a stain found at the crime scene is an organic/biological fluid, such as fruit/vegetable juices, or ultimately a human body fluid, and then identifying and characterizing it, is of great value. Bringing bodily fluids to a state where they can serve as evidence and doing so quickly play a significant role in solving the case and ensuring justice is served properly. The situation where forensic tests in forensic science can often be limited due to sample destruction, long test durations, difficulties in characterizing an unknown stain at the crime scene, in short, the insufficiency of conventional methods, is a well-known issue. Within the scope of a doctoral thesis, the aim was to provide a rapid and accurate detection and diagnosis of small amounts of evidence materials using Raman and Surface-Enhanced Raman Spectroscopy (SERS) by utilizing different nanotechnological analysis methods in place of conventional methods which were considered inadequate in the analysis of bodily fluids. While there are studies in the literature that separately investigate the Raman and SERS spectra of bodily fluids and similar physically similar fluids, there is no study that demonstrates their complex states. In this thesis study, it was aimed to develop a SERS method for the detection of urine, blood, saliva and semen samples when mixed with vegetable/fruit juices with similar physical properties. Raman and SERS analyses were performed using a Raman microscope with a 785 nm laser source. Gold nanorods (AuNRs) and silver nanoparticles (AgNPs) were used for signal enhancement, and their enhancement levels were examined. The results obtained showed that biological fluids can be detected by SERS when mixed with fluids with similar physical properties. Furthermore, it was revealed that AuNR and AgNP significantly increased the signal intensities in SERS spectra. Thanks to the developed method, a fast, non-destructive, and cost-effective method that provides accurate results for the detection of biological fluids in a complex crime scene investigation has been developed. This study was supported by Hacettepe University Scientific Research Projects.