Surface-Enhanced Raman Analysis of Biomedical Eye Lens Extracts

Abstract
This report describes a new application of surface-enhanced Raman spectroscopy (SERS) in the analysis of highly complex and crude biomedical samples. The specific cases examined are ophthalmic extracts obtained from the homogenization of a normal human lens, a senile cataractous human lens, and a chipmunk lens. The results demonstrate that SERS is capable of selectively probing certain biological components with high mass sensitivity. In the chipmunk and normal human lens extracts, adenine-containing molecules (e.g., adenosine-5'-monophosphate) are found to be abundantly present, while intense tyrosine and tryptophan Raman signals are apparent in the SERS spectrum of the cataractous human lens sample. We have also conducted gel-filtration and mass spectrometric studies of the eye lens extracts, and the results indicate that SERS is an effective method for biomedical species identification.