In Situ Surface-Enhanced Raman Spectroelectrochemical Analysis System with a Hemin Modified Nanostructured Gold Surface

An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (<100 μL) with a compact three-electrode configuration for in situ surface-enhanced Raman spectroelectrochemistry. The SEC system includes a nanostructured Au surface that serves dual roles as the electrochemical working electrode (WE) and SERS substrate, a microfabricated Pt counter electrode (CE), and an external Ag/AgCl reference electrode (RE). The nanostructured Au WE enables highly sensitive in situ SERS spectroscopy through large and reproducible SERS enhancements, which eliminates the need for resonant wavelength matching of the laser excitation source with the electronic absorption of the target molecule. The new SEC analysis system has the merits of wide applicability to target molecules, small sample volume, and a low detection limit. We demonstrate in situ SERS spectroelectrochemistry measurements of the metalloporphyrin hemin showing shifts of the iron oxidation marker band ν4 with the nanostructured Au working electrode under precise potential control.