Green synthesis, characterization, morphological diversity, and colorectal cancer cytotoxicity of gold nanoparticles†

The synthesis of gold nanoparticles (AuNPs) via green methods is advantageous due to their economic viability, reduced environmental pollution, and safety towards human health. According to our best knowledge, there is limited documented research on synthesizing AuNPs using gum Arabic (GA) and cinnamon (CNM) and studying their anticancer activities against colorectal cancer cells. This study presents a simple approach to synthesizing AuNPs using GA and CNM, characterized by advanced analytical techniques, including UV-Vis and FTIR spectroscopies, SEM, EDS, TEM, SAED, Zeta sizer, and Zeta potential. The absorption spectra displayed characteristic bands between 520–530 nm, confirming the successful synthesis of AuNPs. TEM analysis revealed that AuNPs@GA exhibited a spherical shape, while AuNPs@CNM displayed diverse morphologies (e.g., spherical, hexagonal, and diamond shapes) with average sizes of approximately 12 nm and 17 nm, respectively. SEM/EDS data confirmed the presence of AuNPs alongside organic compounds such as carbon, oxygen, and phosphorus. The cytotoxic effects of these AuNPs were evaluated on colorectal cancer cells (HCT-116) and healthy cells (HEK-293) using an MTT assay. Notably, AuNPs@GA resulted in a 43.61% loss in cell viability at the dose of 5 μg mL⁻¹, while AuNPs@CNM led to an impressive 80.33% loss. The calculated IC₅₀ values were 9.14 μg mL⁻¹ for AuNPs@GA and 11.76 μg mL⁻¹ for AuNPs@CNM, highlighting the potential of these AuNPs as effective agents in colon cancer treatment. This study not only addresses the lack of research on GA and CNM in NP synthesis but also demonstrates their promising anticancer properties, paving the way for further exploration in cancer therapeutics.