Quartz Crystal Microbalance and Electrochemical Studies on a Viologen Thiol Incorporated in Phospholipid Self-Assembled Monolayers

Abstract

Binary self-assembled monolayers (SAMs) were prepared on gold surfaces by use of a viologen, N-methyl-N'-(10-mercaptodecyl)-4,4'-bipyridinium bishexafluorophosphate (V 1 0 SH) and a phospholipid, dipalmitoylphosphatidylthioethanol (DPPTE). Quartz crystal microbalance (QCM) measurements indicated a similar adsorption trend for the V 1 0 SH and DPPTE assembling on the gold surface. Well reversible redox waves of V 1 0 SH and Fe(CN) 6 3-/4- were recorded for the electrodes modified by either pure V 1 0 SH SAM or binary SAMs prepared in mixed solutions of V 1 0 SH and DPPTE with molar ratios below 1:5. Chronocoulomograms of the SAM-modified electrodes indicated that V 1 0 SH acted as an electron-transfer mediator for the Fe(CN) 6 3-/4- ions in the electrolyte solution to gated access to the electrode surface across the DPPTE monolaver.