Antibacterial activity of biosynthesized green silver nanoparticles from Orthosiphon aristatus against marine bacteria

Abstract

The exceptional antibacterial properties of silver nanoparticles (AgNP) fascinated many researchers to study and exploit this nanomaterial in various applications as a potential antibacterial agent. Nevertheless, it is significant to establish a safe and environmentally friendly synthesis approach. In this sense, green synthesis of AgNP was employed using Orthosiphon aristatus (Misai Kucing) herbal plant as a reducing and capping agent. The brown colour formation of Oa-AgNP colloidal with surface plasmon resonance peak between 410 ran to 480 nm confirmed the reduction of Ag ions into AgNP. The involvement of secondary metabolites as a capping agent was verified through Fourier Transform Infrared Spectroscopy (FTIR) analysis. The crystalline nature of the nanoparticles was characterized using X-ray diffraction (XRD), selected area electron diffraction (SAED) and transmission electron microscopy (TEM). Complementary, the antibacterial activities of the Oa-AgNP were evaluated by disc diffusion technique (DDT) against marine bacteria Bacillus niabensis (16.2 ± 0.23 mm) and Alteromonas litorea (14.2 ± 0.15 mm). While minimum inhibition concentration (MIC) values of the sample against B. niabensis and A. litorea were recorded at 2.5 µg/mL and 5 µg/mL, respectively. The observed results signify the potential of synthesized AgNP using O. aristatus as an effective antibacterial agent specifically for marine-related applications.