The effect of monoethanolamine as stabilizing agent in Uncaria gambir Roxb. mediated synthesis of silver nanoparticles and its antibacterial activity

Abstract

The development of an economic and eco-friendly approach of silver nanoparticles synthesis is an important issue due to its wide application, especially in biomedical applications. In present study, an eco-friendly method and size controlling is developed to synthesize silver nanoparticles using Uncaria gambir Roxb. and monoethanolamine (MEA) as bioreducing agent and stabilizing agent, respectively. The green synthesized silver nanoparticles are characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), and transmission electron microscope (TEM). The silver nanoparticles are formed due to reducing of silver ion by catechin in Uncaria gambir Roxb. leaf extract which is visually recognized from the color change from pale yellow to grayish brown. The formation of silver nanoparticles is confirmed by UV-Vis spectroscopy analysis which provides SPR band range of 405–416 nm. The TEM analysis shows that spherical nanoparticles are formed with size range between 6-39 nm. The using of MEA with molar ratio to Ag+ 10/1 can maintain stability and reduce the particle size up to 40%. The result of XRD analysis shows 4 peaks referring to well-crystallized face-centred cubic silver nanoparticles. The prepared silver nanoparticle has exhibited good stability for more than 6 months. The synthesized silver nanoparticles exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli strain with a diameter of inhibition zone up to 36 mm. The synthesized silver nanoparticles also showed better activity against Escherichia coli than that of Staphylococcus aureus. These results show a good potential of Uncaria gambir Roxb. mediated silver nanoparticles to be developed in biomedical application.