Self-Assembly of Cysteine Dimers at the Gold Surface: A Computational Study of Competing Interactions

Abstract

The only proteinogenic acid with a mercapto group, cysteine is the main participant in the binding of proteins and peptides to the surfaces of noble metals. A chiral molecule, it becomes a major player in surface patterning for chiral amplification, biosensing, and chiral catalysis. Here, we examine the interplay of molecule–surface and molecule–molecule interactions in the self-assembly process of monomers, dimers, and trimers of l-cysteine on a (1 × 2)-reconstructed Au(110) surface, and the implications for chiral recognition. Multiple adsorbed configurations of l-cysteine and l-cysteinate in neutral and zwitterionic forms were generated using molecular dynamics simulations, serving as starting points for further density functional theory (DFT)-based optimizations. We found that binding for both monomers and dimers was stronger at kink sites formed on the surface during the chemisorption process, and was unlikely to occur along the highly coordinated trough sites. In this, DFT calculations disagreed wit...