Surface-Enhanced Raman Scattering (SERS) Analysis of Urea Trace in Urine,Fingerprint, and Tear Samples

The detection of molecular biomarkers of various diseases in biologic fluids is of paramount interest in the field of biomedicine. In this work we demonstrate a direct and reliable identification of urea metabolic by-product in two particular biological fluids, namely, tears and fingerprints, by surface-enhanced Raman scattering (SERS) using gold colloidal particulate films as active plasmonic substrates. The SERS analysis of urea in tears and fingerprint samples produced in the secretions of the sebaceous and eccrine glands, respectively, was directly correlated with SERS analysis of urea in urine samples collected from the same volunteer. We demonstrate a high level of sensitivity and reliability, which would allow this method to be extended for monitoring other biomarkers present in these special biologic fluids as proteins and metabolites. Additionally, the SERS analysis is far less invasive than any other conventional analysis, such as the blood urea nitrogen test, which requires blood samples.