As submitted by the proposer: The purpose of this proposal is to learn about the fundamental capabilities of surface enhanced Raman spectroscopy (SERS) for the detection, identification and characterization of trace amounts of blood, semen, vaginal fluid and saliva and their mixtures for forensic purposes. Development of this optical methodology will lead to a single instrumental platform for the rapid, sensitive, easy-to-use, cost-effective, on-site, non-destructive, detection and identification of human body fluids at a crime scene. No such platform is currently available for this forensic purpose. The successful development of the SERS technology could be transformative allowing the identification of the biological materials/fluid type with minimal destruction to evidence samples at crime scene locations or from evidence taken from crime scenes. Due to the sensitivity of SERS, suspected human body fluid samples that may be invisible to the eye (but may be evident with the aid of alternate light sources), can be identified leaving sufficient quantity for subsequent DNA analysis. In forensic lab settings, SERS can be used to identify the original body fluid at the time of genetic analysis. In addition, SERS can determine the age of some biological stains and corresponding time since a violent crime. Thus, these SERS measurements have the capability to inform criminal investigation directions prior to traditional confirmatory laboratory testing.
This project leverages the expertise developed previously in the PI's lab for other SERS based bioanalytical applications. SERS protocols for acquiring SERS spectra of dried blood, semen, vaginal fluid and saliva will be optimized, and the ability of this approach to identify trace amounts of these body fluids on a variety of surfaces will be demonstrated. Sensitivity, sample and donor heterogeneity, sample age and body fluid mixture resolution capabilities will be determined and quantified. Multivariate data analysis procedures based on the sign of the second derivative of the SERS spectra will be developed for automated body fluid identification. Multivariate statistical analyses will also be exploited for determining molecular components of the SERS spectra and for robust body fluid mixture resolution. In addition to analytical sensitivity and specificity measures of this rapid optical approach, the SERS identification capabilities will also be used to test discarded casework relative to gold standard measures. At the end of this award period, all the elements for an integrated SERS based, portable trace body fluid detection and identification platform (sample preparation protocols, reference spectral library, software procedures) will be available for field deployment and testing.