Antibacterial Thermoplastic Polyurethane Electrospun Fiber Mats Prepared by 3-Aminopropyltriethoxysilane-assisted Adsorption of Ag Nanoparticles

Antibacterial thermoplastic polyurethane （TPU） electrospun fiber mats were prepared by adsorption of Ag nanoparticles （Ag NPs） onto TPU/3-aminopropyltriethoxysilane （APS） co-electrospun fiber mats from silver sol. The use of APS can functionalize TPU fibers with amino groups, facilitating the adsorption of Ag NPs. The effects of pH of silver sol and APS content on Ag NP adsorption and antibacterial activity were investigated. Ag NP adsorption was evidenced by TEM, XPS and TGA. Significant Ag NP adsorption occurred at pH = 3-5, The main driving force for Ag NP adsorption is electrostatic interaction between --NH3^＋ of the fibers and --COO- derived from the --COOH group capped on the surfaces of Ag NPs. The antibacterial activity of the Ag NP-decorated TPU/APS fiber mats was investigated using both gram-negative Escherichia coli and gram-positive Bacillus subtilis. The antibacterial rate increases with increasing APS content up to 5% where the antibacterial rates against both types of bacteria are over 99.9%.

Improved Mechanical Properties of Poly(butylene succinate) Membrane by Co-electrospinning with Gelatin

Gelatin, a natural proteinous polymer, was used to co-electrospin with poly（butylene succinate） （PBS） in order to improve the mechanical properties of PBS membrane and facilitate its applications in biomedical field. The PBS/gelatin blend membranes have narrower distribution of fiber diameter and smoother surface than neat PBS membrane. The contact angles, water absorption rates and water uptakes of the PBS/gelatin blend membranes were measured, showing increased hydrophilicity. The interaction between PBS and gelatin was investigated by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR） and differential scanning calorimetry （DSC）. The mechanical properties of PBS/gelatin blend membranes in both dry and wet states were evaluated by uniaxial tensile tests. In the dry state, the PBS/gelatin blend membrane containing 10% gelatin has a 3-times increase in tensile strength without any adverse effect on ductility because of the existence of interaction between the two blend components, little change in crystallinity of PBS, and possible interaction between any adjacent fibers; the tensile strength and elongation at break are even better in the wet state attributed to some gelatin on fiber surfaces, which act as a binder in the presence of water. The potential applications of PBS/gelatin blend membranes were demonstrated by successful immobilization of thrombin, a clinically-used hemostatic drug. The thrombin-loaded membrane could be used for rapid hemostasis.