Aburrow Steele, Kong Na, Jeyachandran Thanojan, Yin Huaying, Wong See Yoong, Pigram Paul J, Yang Wenrong, Marceau Ross K W
Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
School of Life and Environmental Science, Centre for Sustainable Bioproducts, Deakin University, Waurn Ponds, Victoria 3216, Australia.
Langmuir. 2025 Oct 7;41(39):26855-26865. doi: 10.1021/acs.langmuir.5c03563. Epub 2025 Aug 27.
Purine-modified gold nanoclusters (Au NCs) of diameter 1.4 ± 0.34 nm have been synthesized through a modified, single-phase Brust-Schiffrin method with the introduction of a controlled nucleation approach. The synthesized Au NCs present high chemical stability in neutral to basic environments and across various salt concentrations (NaCl and PBS buffer (pH:7.4)), which overcomes previous size and water-solubility limitations and highlights opportunity for future bioimaging and biosensor applications. The stability of these purine-modified Au NCs in pure water is attributed to the large electron cloud density of sulfur prompted by a greater prevalence of negatively charged nitrogen groups during thiol adsorption. This facilitates a high density and efficient packing of the functional, self-assembled monolayer that protects the Au core from direct interaction with the liquid environment. The combination of reduced size and improved distribution of 6-mercaptopurine, including the increased contribution of Au(I) complexes, has led to increased fluorescence emission intensity of these purine-modified Au NCs. Overall, the synthesis protocol developed in this work provides the foundation for a tailored approach to create a stable, green-fluorescent, water-soluble dispersion of thiol-stabilized Au NCs for bio-related nanotechnology applications.
