Silver nanoparticles green-synthesized ethanol-water extract of Cleistocalyx operculatus buds and their antimicrobial activities

In the current study, using Cleistocalyx operculatus bud extracts to synthesize silver nanoparticles is considered a novel, eco-friendly, and low-priced process that advances chemical and physical methods. Cleistocalyx operculatus bud extracts played a dual part in reducing and stabilizing silver nanoparticles. The formation of silver nanoparticles was recognized on UV-Vis spectra at an absorption maximum of 432 nm. Transmission electron microscopy images detected the quasi-spherical nanoparticle shape with an average size of 26.2 nm corresponding with water extract and 27.5 nm synthesized by ethanol-water extract. The obtained silver nanoparticles had moderate stability with zeta potential ranging from −15.4 to −38.4 mV. The phase purity of the bio-synthesized materials was confirmed by an X-ray diffraction pattern. The Fourier-transform infrared analysis demonstrated hydroxyl groups acting as stabilizing agents in the extract. Silver nanoparticles synthesized from ethanol-water extract exhibited higher antibacterial and anticancer activity than nanomaterials prepared with water extract. Positive-gram bacteria (Bacillus subtilis, Lactobacillus fermentum, and Staphylococcus aureus, negative-gram bacteria (Escherichia coli, Pseudomonas aeruginosa, and Salmonella enterica), and cancer cell lines (lung cancer A549, hepatic cancer Hep-G2, epidermal carcinoma KB, and breast cancer MCF-7) were both inhibited by the nanoparticles synthesized with ethanol-water extract.