Zwitterionic Core-Sheath Nanofibers in Antibacterial Photodynamic Therapy

Skin wounds and their related bacterial infections are one of the issues that would seriously threaten public health. Wound dressings affording antibiofouling capability and incorporating antimicrobial agents could prevent infection and favor wound healing, which have significant clinical demands and value. Antibacterial photodynamic therapy (aPDT) induces toxic singlet oxygen to kill microbes through a photodynamic pathway that avoid the development of drug-resistant microbes. In this study, coaxial electrospinning technology was employed to fabricate an antibacterial wound dressing containing thermoplastic polyurethane (TPU) as the core and zwitterionic and cross-linkable polysulfobetaine copolymer as the sheath. The prepared nanofibrous membranes exhibited good water uptake and retention capability, excellent in vitro biocompatibility and antifouling performance. The elastic properties of TPU improved the stretching and mechanical performance of the membranes that mimic the extensibility of the human skin. Moreover, methylene blue-loaded nanofibrous membranes have shown good antibacterial photodynamic inactivation against Gram-positiveStaphylococcus aureus (99.875%, 2.90 log units inactivation) and Gram-negative Escherichia toll (99.705%, 2.53 log units inactivation) upon mild light irradiation (500 W m(-2)), while as expected, E. coli cells have shown lower susceptibility to aPDT. Overall, the zwitterionic core-sheath nanofibrous membranes with aPDT function are potentially used as a promising antibacterial wound dre ss ing.