Preparation, characterization, and antibacterial activity of green-biosynthesised silver nanoparticles using Clinacanthus nutans extract

Abstract

Plant leaf extract can be used as a reducing agent in the synthesis of silver nanoparticles (AgNP) in a green and safe way. As a result, this study describes the synthesis of AgNP using a Clinacanthus nutans plant extract. C. nutans is known as belalai gajah in Malaysia and is widely used as a medicinal herb. UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and transmission electron microscope (TEM) were used to characterize the biosynthesized AgNP using C. nutans aqueous extract at pH 10, 70°C, and a reaction time of 48 hours. The UV-Vis spectra revealed a peak around 400 nm, while XRD confirmed AgNP's crystal structure, which had an average size of 20 to 30 nm, as shown in FESEM and TEM micrographs. The antibacterial activity of biosynthesized AgNP against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was tested using the disc diffusion technique (DDT). Antibacterial activity was limited against Enterococcus faecalis and methicillin-resistant Staphylococcus aureus (MRSA). AgNP, which was synthesized using C. nutans leaf extract AgNP as a bioreducing agent, has antibacterial activity against a wide range of bacteria in general.