Amino acid driven synthesis of gold nanoparticles: A comparative study on their biocompatibility

Gold nanoparticles (GNps) were successfully synthesized via 17 different l-Amino acids (AA-GNps) as reducing agents, in a one-pot reaction. Comparative characterization of AA-GNps revealed variations in their size, morphology, and structure, highly dependent on the nature of the employed amino acid. Aromatic amino acids proved to be fast-reducing agents directing the formation of GNps. Hydroxylic and basic amino acids were the slowest reducing agents for the synthesis of GNps. Aliphatic amino acids produced GNps of similar behavior, except Isoleucine which led to the formation of hollow nanospheres. GNps formulated by aspartic acid and asparagine have comparable properties to citrate-synthesized GNps, which is the golden standard in plasmonic nanoparticles. A new protocol was established for the determination of gold content in GNps’ colloidal solutions via a simple and cost-effective standard curve method employing UV–Vis spectroscopy. Most AA-GNps are colloidally stable, in both aqueous dispersion and simulated body fluid, posing as excellent candidates for in vitro experimentation. Comparative screening for their biocompatibility demonstrated the non-hemolytic and cytocompatible profile of most AA-GNps, via different in vitro assay protocols, performed on blood samples and the healthy cell line of Human Embryonic Kidney cells (HEK-293).