Biosynthesis of silver nanoparticles using Camonea bifida leaf extract and investigation of antimicrobial properties

Abstract

Silver nanoparticles (AgNPs) have been used in nanomedicine as an alternative antimicrobial agent and disinfectant. The biological synthesis of silver nanoparticles has gained much attention due to its eco-friendly and less toxic nature. The present study was focused on the biosynthesis of AgNPs using Camonea bifida leaf extract and the investigation of their antimicrobial and antibiofilm properties. Aqueous leaf extract (5 g/100 mL) of Camonea bifida was subjected to heat treatment at 60􀁱C. For the optimization of synthesis, parameters including AgNO3 concentration, AgNO3: plant extract ratio, and reaction temperature were studied. The formation of AgNPs was confirmed by the UV-Visible absorption spectrum. Particle characterization was performed using Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and stability study. Antimicrobial activity was studied using well diffusion method against Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 1706), Candida glabrata (ATCC 90030), Candida albicans (ATCC 10231), and Candida tropicalis (ATCC 13803). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed for Staphylococcus aureus and Pseudomonas aeruginosa. Gentamicin (600 μg/mL) and Fluconazole (500 μg/mL) were used as positive controls. The antibiofilm activity of AgNPs against Pseudomonas aeruginosa and Candida glabrata was performed using crystal violet assay. Color change and UV-Visible peak around 450 nm confirmed the formation of AgNPs. FT-IR spectrum indicated the presence of different functional groups of biomolecules such as O-H, C-H, C=O, C-N on the surface of AgNPs. The phytochemical analysis confirmed the presence of flavonoids, phenols, tannins, terpenoids, and chalcones as reducing and capping agents. TEM and SEM results indicated spherical-shaped AgNPs with an average size of 34 nm. AgNPs were stable for more than 4 weeks under room conditions. Pseudomonas aeruginosa (15.0±0.0 mm) and Staphylococcus aureus (16.0±0.6 mm) showed the highest sensitivity towards AgNPs while Escherichia coli showed moderate results (12.7±0.9 mm). Klebsiella pneumoniae and other Candida species did not respond except Candida tropicalis (10.3±0.3 mm). MIC and MBC of AgNPs against Staphylococcus aureus were 20.6 μg/mL and 41.3 μg/mL. MIC and MBC of AgNPs against Pseudomonas aeruginosa were 5.2 μg/mL and 10.3 μg/mL respectively. The percentage inhibition of biofilm formation of Pseudomonas aeruginosa and Candida glabrata was 69% and 61% respectively for 650 μg/mL AgNPs concentration. The overall results indicated the potential of using Camonea bifida mediated AgNPs as a promising antimicrobial and antibiofilm agent.