Preparation and characterization of bioactive polyvinylpyrrolidone film via electrospinning technique.

Electrospinning technique became a very common and effective method to fabricate nonwoven films with a large surface area for different purposes especially in the biomedical field. Antimicrobial submicron fibrous films based on polyvinylpyrrolidone (PVP) doped with silver nanoparticles (Ag-NPs), Zinc Oxide (ZnO), and (Ag-NPS/ZnO), were successfully fabricated via the electrospinning technique. The morphology and the elemental configurations of the as-prepared films were studied by using scanning electron microscope with EDX. While the phase formation and crystal structures were determined by using XRD analysis. The antibacterial effect was investigated against one of the most common Gram-negative bacteria Klebsiella pneumoniae by using a modified Kirby-Bauer disc diffusion method. The results showed that the doping nanoparticles were uniformly loaded on the surface of the fabricated film fibers. By using Scherrer equation the calculated average crystallite sizes of Ag-NPs, ZnO, and Ag-NPs/ZnO on PVP fibers were 63, 30, and 44 nm, respectively. The antimicrobial activity against Klebsiella pneumoniae showed the growth inhibition zones in the bacteria plates of 23.3, 54, and 60.6 mm for the samples of Ag-NPs/PVP, ZnO/PVP, and Ag-NPs/ZnO/PVP, respectively. The antimicrobial efficiency increased by forming nanocomposites of both ZnO nanoparticles and Ag nanoparticles inside the film. RESEARCH HIGHLIGHTS: Novel antimicrobial submicron electrospun membranes based on polyvinylpyrrolidone doped with silver, zinc oxide nanoparticles were successfully fabricated. The fabricated samples showed bactericidal activity against K. pneumoniae.

Preparation and Biological Activity of New Collagen Composites, Part I: Collagen/Zinc Titanate Nanocomposites.

The aim of this investigation was to develop new antimicrobial collagen/zinc titanate (ZnTiO3) biomaterials using a sol-gel cryogenic draying technology in keeping the native collagen activity. Broad-spectrum antimicrobial activity was demonstrated against Firmicutes (Staphylococcus epidermidis, Bacillus cereus, and Candida lusitaniae) and Gracilicutes (Escherichia coli, Salmonella enterica, and Pseudomonas putida) microorganisms. The antimicrobial activity as well as the cytotoxicity were specific for the different test microorganisms (Gram-positive and Gram-negative bacteria and fungi) and model eukaryotic cells (osteosarcoma, fibroblast, and keratinocyte cells), respectively, and both were depending on the ZnTiO3 concentration. Three mechanisms of the antimicrobial action were supposed, including (i) mechanical demolition of the cell wall and membrane by the crystal nanoparticles of the ZnTiO3 entrapped in the collagen matrix, (ii) chelation of its metal ions, and (iii) formation of free oxygen radicals due to the interaction between the microbial cells and antimicrobial agent. It was concluded that the optimal balance between antimicrobial activity and cytotoxicity could be achieved by a variation of the ZnTiO3 concentration. The antifungal and broad-spectrum antibacterial activity of the studied collagen/ZnTiO3 nanocomposites, combined with a low cytotoxicity, makes them a promising anti-infection biomaterial.