Green gold nanoparticle synthesis and anticancer activity

Breast cancer is the most common cancer in both South Africa and globally. Despite significant advancements in cancer therapy over the past century, challenges in treatment efficacy remain, requiring novel solutions with fewer side effects.

Nanotechnology offers promise, particularly gold nanoparticles (GNPs), due to their stability, ease of functionalisation, and low cytotoxicity. However, traditional GNP synthesis is hindered by high production costs and toxic by-products. Green synthesis has emerged as an eco-friendly, cost-effective alternative for producing green gold nanoparticles (GGNPs).

This study utilised Tannic Acid, Gallic Acid, and Quercetin—plant-derived compounds with known anticancer activity but poor solubility and rapid clearance—as reducing and capping agents in the synthesis of GGNPs. The formation of nanoparticles was confirmed by a colour change and UV-visible spectroscopy, with absorbance peaks at 515 nm, 555 nm, and 562 nm. Dynamic light scattering (DLS) revealed particle sizes of 86 nm, 32 nm, and 112 nm, with polydispersity indices (PDI) of 0.35, 0.31, and 0.16, respectively. Zeta potentials of -41, -37, and -47 mV confirmed sample stability, which was maintained over three months at room temperature and 4°C. GGNPs were further characterised with Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy.

Each GGNP exhibited antioxidant and anticancer activity, which was tested against MDA-MB-231 and MCF-7 breast cancer cell lines, as well as normal breast epithelial MCF-12 cells. This study highlights the potential of GGNPs as a targeted, eco-friendly therapy for breast cancer.