Uncaria gambir Roxb. mediated synthesis of stable silver nanoparticles in the presence of triethanolamine as the capping agent

Abstract

The study of silver nanoparticles (AgNPs) fabrication has gained great interest especially for pharmaceutical applications due to its excellent antibacterial properties. AgNps are well known for their inhibitory and bactericidal effects both on positive and negative gram bacteria. However, the utilisation of some chemical reducing agents in the synthesis process can be harmful to the environment and the human body. Green synthesis of silver nanoparticles has been successfully conducted using an aqueous extract of Uncaria gambir Roxb. (UGR) leaves as a bioreducing agent and triethanolamine as a capping agent, reacted with aqueous AgNO3 as the precursor. The formation of silver nanoparticles was visually revealed by colour change from yellow to brown. It was also confirmed by UV-visible (UV-Vis) spectrophotometer analysis by absorption peaks at 402–414 nm. The result of X-ray diffraction (XRD) analysis showed 5 peaks referring to face-centred cubic silver nanoparticles. Transmission electron microscope (TEM) analysis showed that spherical silver nanoparticles with a size range of 2–18 nm with a mean diameter of 8 nm have been formed. The result showed that the addition of 1/50 mL triethanolamine (TEA) could enhance the stability of colloidal nanoparticles and reduce the particle size up to 65%. This study confirmed that UGR aqueous leaf extract can be used to mediate rapid, environmentally friendly, and less expensive silver nanoparticles fabrication.