Voltammetric and surface-enhanced resonance Raman spectroscopic characterization of cytochrome C adsorbed on a 4-mercaptopyridine monolayer on silver electrodes.
To combine voltammetric techniques with surface-enhanced resonance Raman scattering (SERRS), cytochrome c (cyt c) was immobilized on a roughened silver electrode chemically modified with a self-assembled monolayer (SAM) of 4-mercaptopyridine (PySH). All measurements were performed on the same electrode in a homemade spectroelectrochemical cell suitable for such applications. Cyt c on a PySH-SAM shows a quasi-reversible, monoelectronic, adsorption-controlled CV response with a formal reduction potential of -0.061 V (vs SCE), which is comparable to the values found for native cyt c adsorbed on different SAMs. SERRS spectra proved that cyt c adsorbed on a PySH monolayer is present in the native conformer (the B1 state). Voltammetric and SERRS experiments at high ionic strength revealed that the interaction between the SAM and the protein is electrostatic in nature. In conclusion, PySH was found to be suitable for adsorption of cyt c at SERRS-active silver surfaces. In comparison with other SAMs, PySH requires less time (10 min vs 12-18 h) to form a long-time durable and reproducible coating on the roughened electrode surface.
Millo
D
D
Laser Centre - Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
Bonifacio
A
A
Ranieri
A
A
Borsari
M
M
Gooijer
C
C
van der Zwan
G
G
D000818:Animals; D002417:Cattle; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D009206:Myocardium / Q000378:metabolism; D011725:Pyridines / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D011725:Pyridines; D012834:Silver; C042861:4-thiopyridine; D045304:Cytochromes c