Assessment of biological activities of silver and gold nanoparticles synthesized from Persea americana Mill. leaves

Nanotechnology, due to its multidisciplinary fields within the of science and technology, has gained popularity, especially in the production and use of nanoparticles. Additionally, there is an increasing interest in the development of innovative and environmentally friendly scientific methods as a result of global changes. The aim of this thesis is to perform silver and gold nanoparticles synthesis through leaf extract of Persea americana Mill. (avocado) and examine the biological activities of synthesized silver and gold nanoparticles. Persea americana Mill. is a plant that can naturally grow without need for industial agriculture and can be also cultivated in the Mediterranean region. It holds an important place in terms of pharmacological, cosmetics, and dietary aspects with both its fruits and leaves containing essential nutrients. In this prepared thesis, leaf extract was prepared from Persea americana Mill. (avocado), and then silver and gold nanoparticle synthesis was carried out using a green synthesis approach. According to obtained results, the solution color turned from yellowish to reddish-brown in the case of silver nanoparticle synthesis while the solution color changed from yellow to red in gold nanoparticle synthesis. Various methods such as ultraviolet-visible (UV-Vis) spectroscopy, Fouriertransform infrared spectroscopy (FT-IR), scanning transmission electron microscopy with energydispersive X-ray spectroscopy (STEM), X-ray diffraction (XRD), nanoparticle size and Zeta potential measurements were utilized to examine the nanoparticles structurally and morphologically. When the characterization findings are examined, it is determined that silver nanoparticles generally have a spherical shape and are observed in the range of approximately 12.18 ± 2.18 nm, while gold nanoparticles exhibit both spherical and triangular morphologies with average dimensions of 14.84 ± 3.99 nm. Antioxidant activity tests were performed using various methods, including total phenolic and total flavonoid substance, as well as total antioxidant capacity (phosphomolybdate), DPPH, ABTS, CUPRAC, FRAP, and metal chelation for avocado leaf extract and silver and gold nanoparticles synthesized from the extract. In the antioxidant tests, silver nanoparticles exhibited phosphomolybdate activity of 0.29 mmol TE/g, DPPH activity of 20.94 mg TE/g, ABTS activity of 25.66 mg TE/g, CUPRAC activity of 61.39 mg TE/g, and FRAP activity of 41.99 mg TE/g, while gold nanoparticles showed phosphomolybdate activity of 0.05 mmol TE/g, DPPH activity of 28.14 mg TE/g, ABTS activity of 1.40 mg TE/g, CUPRAC activity of 35.50 mg TE/g, and FRAP activity of 21.48 mg TE/g. The obtained results demonstrate