The stability and electronic properties of amino acids conjugated gold clusters was investigated using DFT. Specifically, Au8 (D4h) and Au20 (Td) clusters interacting with tryptophan (Trp) and alanine (Ala) amino acids was considered. The geometrical structures of the Au clusters along with the polarity of the amino acids determine the nature of the interactions in the gas and solvent phases. In the gas phase, the Au8 (D4h) and Au20 (Td) clusters prefer single-site interaction through the amine group for the canonical amino acids, while in the solvent phase, the carboxylic site is preferred for the zwitterionic amino acids. The cluster-size defines the extent of the interactions and overall stability of the complexes. The structures of Au clusters govern the charge distribution and electrostatic potential directing the selectivity towards the preferential binding sites with the Ala and Trp amino acids.

Marwa H Abdalmoneam, Kevin Waters, Nabanita Saikia, and Ravindra Pandey, J. Phys. Chem. C, 2017, 121, 25585-25593.