Chemoselectivity and the Chan-Lam Coupling Reaction: Adding Amino Acids to Polymer-Coated Microelectrode Arrays.

The placement of a peptide onto a microelectrode array is frequently complicated by the presence of multiple nucleophiles in the peptide. In the work reported here, we have found that the Chan-Lam coupling reactions used to site-selectively place thiol, alcohol, and amine nucleophiles onto diblock-copolymer-coated surfaces are chemoselective for the placement of thiol and alcohol nucleophiles on the arrays. This means that cysteine- and serine-containing peptides can be placed onto an array without any need to protect the N terminus of the peptide. Furthermore, it was found that placement of thiol groups onto an array with the Chan-Lam reaction using optimized reaction times leads to complete coverage of the electrodes. The extent of this coverage can be controlled by varying the reaction time in a manner that allows for the construction of arrays with a gradient of peptide concentrations.