Study of biomolecules by combining electrochemistry with UV/Vis, IR and surface enhanced Raman scattering spectroscopy by a novel flow microcell

A flexible, easy to disassemble and reassemble, multifunctional flow spectroelectrochemical microcell combining flowing injection electrochemical detection and high resolution of spectroscopies, such as UV/Vis, FT-IR and surface enhanced Raman scattering (SERS) are described. The volume and the optical path are adjustable over 3 orders of magnitude (from 1 mu l to 1 ml) and more than 2 orders (from 0.020 to 5 mm), respectively. With this device the studies of redox-induced conformational change of hemoglobin and the adsorptive behavior of NAD(+) at the surface of silver electrode are carried out with in situ UV/Vis, FT-IR and SERS spectroelectrochemistry. The attribution of spectral bands of reduced and oxidized hemoglobin allows the use of FT-IR difference spectra as probes not only for revealing the interaction between the local hemins and their environment but also for the understanding of the action of different subunits of hemoglobin. The observation of the SERS spectra as a function of working potentials revealed the adsorption/deadsorption behavior and the orientation of NAD(+) adsorbed at the surface of the silver electrode. All the acquired spectral data show the considerable potential to facilitate to the further understanding at the molecular level of the interaction between the coenzyme NAD(+) and the charged biological interface (such as cell membrane). The fabricated microcell and established method can be widely applied to the various studies of in situ spectroscopy electrochemistry. (C) 1999 Elsevier Science B.V. All rights reserved.