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

UV-assisted reduction of in situ electrospun antibacterial chitosan-based nanofibres for removal of bacteria from water

A greener synthesis of low-swelling uniformly-sized chitosan (CTS)-based nanofibres decorated with silver (Ag) and silver/iron (Ag/Fe) nanoparticles is reported. The synthesis was achieved by electrospinning a solution of CTS blended with varying amounts of polyacrylamide (PAA), polyethylene glycol (PEG) and Ag+ or Ag+/Fe3+ ions. These nanofibres were subjected to UV irradiation under ionised water vapour at low temperature (70 degrees C). The effect of UV irradiation time on the reduction of the NPs was confirmed using UV-Vis spectroscopy. The microstructure and chemical composition of the Ag and Ag/Fe modified nanofibres was studied using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy (UV-Vis). TEM revealed that the average diameter of the CTS-based nanofibres, AgNPs, and Ag/Fe NPs supported on the CTS-based nanofibres were 471 +/- 89 nm, 18 +/- 2.5 and 32 +/- 8.7 nm respectively. XRD and EDS analysis confirmed the presence of Ag and Fe in the nanofibers. The biocidal effect of the Ag and Ag/Fe NPs supported on the CTS-based nanofibres was investigated using Gram positive (Bacillus cereus, Enterococcus faecalis) and Gram negative (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus mirabilis, Shigella boydii, Shigella sonnei, Enterobacter cloacae) bacterial strains. The nanofibres exhibited a strong biocidal effect on the bacteria suggesting that they can be used as efficient antimicrobial materials in water systems that are contaminated by bacteria

Galactosemia, a single gene disorder with epigenetic consequences

Long-term outcomes of classic galactosemia (GAL) remain disappointing. It is unclear if the complications result mainly from prenatal-neonatal toxicity or persistent glycoprotein and glycolipid synthesis abnormalities. We performed gene expression profiling (T transcriptome) to characterize key-altered genes and gene clusters of four patients with GAL with variable outcomes maintained on a galactose-restricted diet, compared with controls. Significant perturbations of multiple cell signaling pathways were observed including mitogen-activated protein kinase (MAPK) signaling, regulation of the actin cytoskeleton, focal adhesion, and ubiquitin mediated proteolysis. A number of genes significantly altered were further investigated in the GAL cohort including SPARC (osteonectin) and S100A8 (S100 calcium-binding protein). The whole serum N-glycan profile and IgG glycosylation status of 10 treated patients with GAL were compared with healthy control serum and IgG using a quantitative high-throughput analytical HPLC platform. Increased levels of agalactosylated and monogalactosylated structures and decreases in certain digalactosylated structures were identified in the patients. The persistent abnormal glycosylation of serum glycoproteins seen with the microarray data indicates persisting metabolic dyshomeostasis and gene dysregulation in “treated” GAL. Strict restriction of dietary galactose is clearly life saving in the neonatal period; long-term severe galactose restriction may contribute to ongoing systemic abnormalities