Evaluation of anti bacteria effects of citrate-reduced silver nanoparticles in Staphylococcus aureus and Escherichia coli

Abstract

Silver nanoparticles (AgNPs) has long known for its inhibitory and bactericidal effects. However, due to its’ attractive antibacterial property, on-going research with various synthesis strategies actively been conducted. In this study, the synthesis of AgNPs was reported, using a simple chemical reduction method with citrate as the reducing agent TEM was used to characterize the obtained AgNPs. Then, Staphylococcus aureus and Escherichia coli were used to identify the antibacterial activity of AgNPs. The inhibition effects of AgNPs against these two bacteria were observed via disc diffusion, and MIC assays and the effects of AgNPs mode of action on both bacteria were further observed under TEM. The formation of AgNPs at ̴ 400 nm, which is the surface plasmon resonance peak was observed using Uv-Vis spectroscopy. The size of AgNPs mostly in the range of 1-10 nm and their morphology appeared to be spherical. Based on the MIC assay, Escherichia coli exhibit low MIC value with 0.049 mg/ml as compared to Staphylococcus aureus with0.391 mg/ml MIC value; correspond to the effective antibacterial activity by the citrate-reduced AgNPs. Further observation on the bacterial surface structure can be seen with cross-sectional TEM image, and it provides an insight into the AgNPs mechanistic aspects of AgNPs against Staphylococcus aureus and Escherichia coli. Silver nanoparticles have been successfully synthesised using the citrate reduction method. Results obtained in this study thus elucidating promising findings to employed AgNPs as an antibacterial agent, and this composition needs to be further study and develop into an antibacterial agent.