Highly sensitive detection of blood by surface enhanced Raman scattering.

Raman spectroscopy for forensic body fluid analysis has received some attention due to the nondestructive nature and potential application for identification at the crime scene; however, its usage has been limited by low detection sensitivity. Surface enhanced Raman scattering (SERS) was evaluated for blood identification for forensic applications. Specifically, a SERS-active substrate was fabricated, composed of nickel nanotips coated with Ag nanoparticles. Compared with a conventional substrate, the SERS substrate enhanced Raman scattering by more than two orders of magnitude and allowed blood to be identified to a dilution of 1:100,000. Blood was also successfully detected by swabbing the SERS substrate directly on mock evidence. Most importantly, Raman spectra obtained by swabbing the SERS substrate on blood stains were free of luminescence even when blood was deposited on luminescent fabrics. The nondestructive character, simplicity of sample preparation, and high sensitivity make SERS a prime candidate for field and laboratory-based blood identification.