Label-free Rapid Semiquantitative Detection of Proteins Down to Sub-monolayer Coverage by Using Surface-enhanced Raman Scattering of Nitrate Ion

A novel heat-induced SERS method was used to selectively enhance a band of NO3- at 1049 cm(-1) for semi-quantitative detection of lysozyme and insulin down to 10(-9) and 10(-8)M, respectively, and bell shape variations of SERS intensifies were observed for the concentration dependency of the proteins