Resumo:
In the present article, the green synthesis of silver nanoparticles (NPsAg) was studied using plant extract of Cinnamomum zeylanicum (Cz-extract) as the reducing agent. The green synthesis of NPsAg was performed in the presence of the polymer matrix of poly (vinyl alcohol) (PVA) and polyglycerol dendrimer (DPG). The Cz-extract was prepared by ultrasonic technique and characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), aiming to evaluate the chemical composition. The UV-vis spectrum confirmed the presence of cinnamaldehyde. FTIR confirmed the presence of carbonyl (C=O) aldehyde, alcohol (O-H) and glycosidic (C-O-C) bonds. The thermogravimetric analysis (TGA) of the Cz-extract confirmed the presence of thermally stable compounds in the plant extract. The green synthesis of NPsAg was performed using different amounts (5, 10 and 20 mL) of Cz-extract. The surface plasmon resonance (SPR) band in the UV-vis spectrum confirmed the formation of NPsAg in the green syntheses studied. The PVA/DPG-NPsAg films were obtained by the pouring technique (solvent evaporation) on Teflon molds. The membranes were obtained from the films after crosslinking PVA with citric acid, aiming at greater dimensional stability. Membranes were characterized by FTIR, TGA, X-ray diffraction (XRD), scanning electron microscopy (SEM) and antimicrobial activity. FTIR and TGA characterization showed differences between uncured (films) and cured (membranes) PVA/DPG-NPsAg systems. The XRD pattern confirmed the presence of metallic silver, with an average crystallite size, calculated by Scherrer, of 13.64 nm, 16.63 nm and 20.27 nm for AgNPs prepared with 5 mL, 10 mL and 20 mL of extract-Cz, respectively. To study the release mechanism of NPsAg, the Korsmeyer-Peppas and Higuchi kinetic model was used. The results suggested that the NPsAg release fit the Korsmeyer-Peppas kinetic model. The antimicrobial results revealed that the PVA/DPG-NPsAg5 system was the one that presented the best antibacterial behavior against Escherichia coli.
