Facile Synthesis of Gold Nanoparticles for Anticancer, Antioxidant Applications, and Photocatalytic Degradation of Toxic Organic Pollutants

In the current study, a facile, rapid, and ecologically safe photosynthesis of gold nanoparticles (AuNPs) that remained stable for 3 months is reported to advocate the main aspects of green chemistry, such as safer solvents and auxiliaries, and the use of renewable feedstock. Zi-AuNPs were phytosynthesized by the aqueous extract of Ziziphus spina-christi leaves, and numerous techniques were employed for their characterization. The results demonstrated the successful phytofabrication of crystalline AuNPs with brownish-black color, spherical nanoparticles with a size between 0 and 10 nm, a plasmon peak at 540 nm, and a surface charge of -25.7 mV. Zi-AuNPs showed an effective photodegradation efficiency (81.14%) against malachite green and a good recycling capacity of 69.2% after five cycles of regeneration. The cytotoxicity test by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay signified a high anticancer efficiency for both Zi-AuNPs and Z. spina-christi extract against human breast cancer cells (MCF7 cell line) with IC50's of 48 and 40.25 μg/mL, respectively. Highly efficient antioxidant capabilities were proven with 2,2-diphenyl-1-picrylhydrazyl (DPPH) removal percentages of 67.5% for Zi-AuNPs and 92.34% for Z. spina-christi extract.