Body Fluid Study by Surface Enhanced Raman Spectroscopy for Medical/Forensic Application

Surface Enhanced Raman Spectra(SERS) of human erythrocytes on Au nanoparticle SiO₂ substrates excited by 785 nm laser radiation in a Raman microscope are reported. These spectra are characterized relative to hemoglobin isolated from red blood cells(RBC) and commercial hematin. The vibrational SERS signal of RBCs originates entirely from near membrane hemoglobin. In particular, the spectrum is dominated by the skeletal modes of the porphyrin ring of the heme moiety and a single non-porphyrin skeletal mode which was identified as the Fe-histidine stretching mode(~1200 cm^-1). Investigation of the applications of SERS for malaria diagnostics reveals the ability of SERS spectra to spectral distinguish hemoglobin, hematin and the chloroquine hematin complex. These results indicate the possible use of SERS for early malaria diagnostics and measures of anti-malarial mechanisms of action. In addition, SERS spectra are found to spectrally distinguish trace amounts of five body flluids: blood, saliva, semen, vaginal fluid and urine for forensics applications. SERS detection provides accuracy of ~90% for all body fluids. SERS detection of blood is determined to be ~50 cells per μL. These results determine that SERS offers a single, rapid, highly sensitive analytical tool for the identification of human body fluids.