Surface-enhanced Raman scattering for label-free protein detection and identification

Surface-enhanced Raman scattering (SERS) is a powerful technique to study the biological molecules and structures. SERS of proteins is always difficult due to their complex, flexible and diverse structures. This difficulty is one of the major obstacles hindering the applicability of SERS for the label-free detection and identification. In this study, we have employed several sample preparation approaches involving the packing AgNPs with protein molecules in a proper manner to allow the polarization of the electron system of proteins in coherence with the nanostructured noble metal system. The applicability of heat denaturation kinetics is perused for the detection and identification of proteins in model protein mixtures. Human serum albumin, transferrin, hemoglobin and the binary mixtures of these proteins are used as models. We have found that the SERS spectrum of each protein in the protein mixture is rather different at an increased temperature, which could be used to distinguish a protein in the protein mixture.