Green synthesis of silver nanoparticles using one-pot and microwave-assisted methods and their subsequent embedment on PVDF nanofibre membranes for growth inhibition of mesophilic and thermophilic bacteria

Antibacterial silver nanoparticles (AgNPs) were synthesised via an environmentally benign thermally-assisted one-pot and microwave-assisted experimental set-up using apple extract as a reducing agent. The formation of these AgNPs was confirmed by UV-Vis, XRD and EDS while their size distribution was determined by TEM micrographs. The AgNPs were uniformly distributed with diameters of 28.24 +/- 1.15 nm and 22.05 +/- 1.05 nm for the thermally-assisted one-pot and microwave-assisted reduction methods respectively. The rate of reduction was faster in a microwave-assisted reduction method compared to that of a thermally-assisted one-pot synthesis method. The antibacterial AgNPs were embedded in polyvinylidene fluoride (PVDF) nanofibre membranes and their antibacterial activity against Gram-positive Geobacillus stearothermophilus and Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa and Klebsiella pneumoniae was studied. The antibacterial nanofibres successfully inhibited the growth of these mesophilic and thermophilic bacteria. Therefore, AgNP-embedded PVDF nanofibre membranes showed a high potential for use in water purification systems that are subject to contamination by mesophilic or thermophilic bacteria without compromising the rate of water recovery.