The primary objective of this research is to synthesize stable, robust 1.1 nm gold/gold-iron nanoclusters (Au25SG18) with glutathione (GSH) as the ligand in high yields. Gold nanoclusters ranging less than 1.6 nanometers exhibit quantum confinement effects and exhibit molecular behavior, which alters their chemical and physical properties with respect to bulk gold. These alterations enable the clusters to exhibit unique optical, catalytic, biomedical and electrochemical properties, which have made these nanoclusters desirable in various fields of study, within and out of the science community. In addition to these unique and invaluable properties, these gold nanoclusters containing 25 gold atoms are extremely stable even amongst its other magic numbered counterparts due to the stability of the icosahedral core and sulfur-gold bonds. The synthesis of these gold clusters is a two-stage reaction. These reactions are carefully controlled in each step to ensure nanocluster size monodispersity. The formation of Au25SG18 is confirmed and characterized using UV-vis spectroscopy, IR spectroscopy, fluorescence spectroscopy, HNMR spectroscopy while core-size of the clusters are measured using SEM and TEM. The synthesized Au25SG18 is then used for various applications such as (i) theranostic breast cancer treatment – via drug delivery by conjugation of Cullin5DNA and a drug molecule using antibodies (ii) imaging applications – for in vivo imaging. To quantify the viability and stability of these gold nanoclusters for biological applications, the nanocluster systems are tested for (i) their stability in different ionic strengths and (ii) their stability in biological media of varying concentrations, which is analyzed through both its zeta potential and DLS profiles. Furthermore, the stability of these systems are analyzed through UV-vis to identify if any aggregation of the nanoclusters occur. Once confirmed of their stability, these gold nanoclusters can be used to study their effectiveness in theranostics.

Improvement of theranostic breast cancer treatment: a study of quantum-confined Au25SG18 nanoclusters

ACS Fall 2021

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