Aqueous leaf extracts of Cnidoscolus chayamansa (Mayan chaya) cultivated in Yucatan Mexico. Part II: Uses for the phytomediated synthesis of silver updates nanoparticles

Hypothesis: Recently proposed alternatives for synthesizing silver nanoparticles involve the use of extracellular extracts of different plants in which the obtained particles show similar or improved characteristics with respect to particles obtained using more conventional methods. On this basis, this paper proposes the synthesis of nanoparticles (NPs) of silver (AgNPs) using aqueous extracts from the leaves of Cnidoscolus chayamansa McVaugh (Mayan chaya or tree spinach). Experiment Ten aqueous extracts from chaya leaves were prepared, varying the proportion of the mass in the extracts (% m/V): 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.5%, 7.5% and 10.0%. Each of the extracts was used as a reducing agent in the green synthesis of AgNPs, using silver nitrate as a precursor salt at an initial concentration of 1.34 mM. The synthesized particles were characterized by UV-Vis spectroscopy, scanning electron microscopy, dynamic light dispersion (DLS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Finding: The non-purified silver particles synthesized with the aqueous chaya extracts were larger than 100 nm. When the extract concentration was increased particles with a different size and shape were obtained, due to variations in the antioxidant capacity of the different extracts. Starting with the 2.0% extract, agglomerated silver particles organized in a cauliflower shape were obtained, with an average size between 264.5 +/- 2.42 and 4610 +/- 17 nm. After the silver particles were purified, in all cases spherical AgNPs measuring < 50 nm were obtained.