ICG-loaded photodynamic chitosan/polyvinyl alcohol composite nanofibers: Anti-resistant bacterial effect and improved healing of infected wounds

Photodynamic antimicrobial chemotherapy (PACT) has advantages of strong targeting, low resistance to drugs. Electrospinning nanofibers is favorable for wound healing. The combination of PACT and electrospinning nanofibers is appropriate for wound healing, especially infected wound. In our study, indocyanine green (ICG) as photosensitizer had obvious inhibition effects on two antibiotic-resistant bacteria, Methicillin-resistant Staphylococcus aureus (MRSA) and Meropenem-resistant Pseudomonas aeruginosa (MRPA). The optimized electrospinning solution consisted of 2% (w/v) chitosan and 7% (w/v) PVA. The nanofibers observed by scanning electron microscope showed a three-dimensional cross-network with smooth surface, the water absorption ratio of the nanofibers was up to 210%. Fourier transform infrared spectrum and X-ray diffraction showed that the intermolecular hydrogen bonding happened between chitosan and PVA in electrospinning process, which was favorable for the formation of nanofibers. ICG released rapidly from the surface of the nanofibers first and then released continuously. The photodynamic nanofibers could inhibit the bacteria and decreased the F4/80 expression of MRSA-infected rats. The improved effects of wound healing were evaluated with the morphology, wound healing radio, the increased expression of cluster of differentiation 31 (CD31), the decreased level of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The photosensitizer-loaded electrospinning nanofibers provide a novel promising option for treatment of infected wound.