Chitosan microflower-embedded gelatin sponges for advanced wound management and hemostatic applications.

The study explored the antimicrobial, antibiofilm, and hemostatic properties of chitosan microflowers (CMF) in sponge form. The main objective was to enhance the preparation of CMF by employing varying quantities of calcium chloride (CaCl2) and tripolyphosphate (TPP). CMF was then combined with gelatin (GE) in different proportions to produce three sponge samples: CMF0@GE, CMF1@GE, and CMF2@GE. The CMF had a morphology like that of a flower and produced surfaces with a porous sponge-like structure. The antibacterial activity, as determined by the zone of inhibition (ZOI), increased with greater doses of CMF. Among the tested samples, CMF2@GE had the greatest activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium. CMF2@GE successfully suppressed biofilm formation, decreased clotting time to an average of 212.67 s, and exhibited excellent biocompatibility by preserving over 90 % viability of human skin fibroblast cells at dosages below 100 µg/mL. The results indicated that gelatin sponges filled with CMF have considerable promise as flexible medical instruments for wound healing and infection control.

Styrene N-vinylpyrrolidone metal-nanocomposites as antibacterial coatings against Sulfate Reducing Bacteria.

Copolymer of styrene, and vinylpyrrolidone was prepared by various techniques. Different nanometals and nanometal oxides were added into the copolymer as antimicrobial agents against Sulfate Reducing Bacteria (SRB). The nanocomposite chemical structure was confirmed by using FTIR, (1)H NMR spectroscopy and thermogravimetric analysis (TGA). The biocidal action of these nanocomposites against the SRB was detected using sulfide determination method in Postgate medium B. The data indicated that the nanocomposites had an inhibitory effect on the growth of SRB and reduced the bacterial corrosion rate of mild steel coupons. The prepared nanocomposites have high inhibition efficiency when applied as coatings and show less efficiency when applied as solids or solution into SRB medium. The copolymer and its nanocomposites effectively reduced the total corrosion rate as determined by total weight loss method.

Antifungal efficacy of chitosan and its thiourea derivatives upon the growth of some sugar-beet pathogens.

Chitosan (CS) was modified by reaction with benzoyl thiocyanate to give a thiourea derivative (TUCS). The antifungal behavior of chitosan and its thiourea derivative was investigated in vitro on the mycelial growth, sporulation and germination of conidia or sclerotia of the following sugar-beet: Beta vulgaris pathogens isolated in Egypt, Rhizoctonia solani Kühn (AG(2-2)) Sclerotium rolfsii Sacc. and Fusarium solani (Mart.) Sacc. All the prepared thiourea derivatives had a significant inhibiting effect on the different stages of development on the germination of conidia or sclerotia of all the investigated fungi in the polymer concentration range of 5-1000 microg ml(-1). In the absence of chitosan and its derivative, R. solani exhibited the fastest growth of the fungi studied. However, growth tolerance of the modified chitosan was highest for F. solani and lowest for R. solani. The most sensitive to the modified chitosan stress with regard to their germination and number produced were the sclerotia of S. rolfsii. It has been found that the TUCS is a much better fungicidal agent (about 60 times more) than the pure CS against most of the fungal strains tested. The molecular weight and the degree of deacetylation were found to have an important effect on the growth activities of the pathogens.

Interpenetrating polymer networks for biological applications.

The use of a sequential polymerization method for preparing interpenetrating polymer networks with biocomatible surfaces has been studied. A hydrogel monomer was made to undergo polymerization with simultaneous cross-link formation, in the presence of a swollen thermoplastic elastomer heterophase block copolymer. On removal of the swelling solvent, an interpenetrating network of the hydrogel and the thermoplastic elastomer was obtained, which absorbed water in the manner of a hydrogel, but had mechanical properties superior to hydrogels. The studies employed a poly(ether-urethane) block copolymer as the thermoplastic elastomer. The materials fabricated included samples in which the interpenetrating polymerization extended throughout the termoplastic elastomer as well as samples in which the interpenetrating polymerization was confined to a region near the surface of the latter.