Interference from trace copper in electrochemical investigations employing carboxylic acid terminated thiol modified gold electrodes

摘要: Unexpectedly, electrochemistry at variable chain length carboxylic acid terminated alkylthiol self-assembled monolayers (SAMs) on gold electrodes gives rise to a Faradaic process in buffered aqueous electrolyte solution. In particular, the three-carbon length, 3-mercaptopropionic (MPA), exhibits chemically reversible with mid-point potential of 175 mV vs. Ag/AgCl under conditions cyclic voltammetry. This is associated presence trace (parts per billion) amounts copper(II) ions present chemical reagents used prepare and also from electrode itself. The moiety SAM concentrates Cu2+ by coordination this surface confined layer then reduced. Methods minimize interference are discussed caution respect interpretation protein recommended when using functionalized SAMs provide biocompatible electrochemical transduction surfaces, unless metal free environment can be obtained.