Application Of Photodynamic Nanofibers In Rapid Hemostasis And Wound Repair

With the rapid development of nanotechnology,the uniqueness and potential applications of nanofibers provide new strategies and opportunities for sustainable social development and creative solutions to biomedical,healthcare and environmental problems.Electrospinning technology is a simple and efficient new preparation technology for the production of nanofiber materials.It has many advantages,such as simple manufacturing device,convenient modification process,wide variety of materials,large specific surface area of the fiber and controllable pores,etc.so it has become the research hotspot of tens of millions of scholars in the 21 st century.Bleeding in outdoors often accompanies bacterial infection.Due to poor outdoor conditions,such as no mains supply and limited first aid materials,it is essential to use the same materials to achieve one-stop service of fast hemostasis and simultaneous sterilizing bacteria,especially for multidrug-resistant bacteria.Photodynamic therapy(PDT)can effectively kill bacteria,and local PDT through nanofiber platform can effectively reduce damages to normal tissues.However,current photosensitizers whether in the inner or on the surface of fibers would release to the wound and inhibit collagen regeneration.Moreover,most photosensitizers were triggered by visible light handicapping their applications in deep tissue.In addition,the traditional electrospun nanofiber membrane is dependent on the electricity,and then the fiber membrane is opened and cut into a certain shape and then covered on the wound.This will lead to poor adhesion between the traditional fibrous membrane and skin tissue and insufficient adhesion,so as to be unable to stop bleeding in time,and reduce the killing effect of short-range effective photodynamic effect on bacteria.Here,we use a battery-powered hand-held electrospinning device that can be used outdoors to directly deposit it on the wound surface for spinning,which has good mechanical properties and will not cause unnecessary friction between the fiber membrane and the wound.The excellent adhesion and adhesion between the fiber and the wound tissue are used to achieve effective hemostasis.The electrospinning material we used has good biocompatibility and degradability,and can also improve the hydrophilicity and hydrophobicity of the fiber.We also propose to elute holes in fibers by wound tissue fluid to accelerate the escape of reactive oxygen species(ROS)from the inner of hydrophobic fibers to the wound.By coating the photosensitizer on the up-conversion particles,the cluster size of the composite nanoparticles was increased to prevent the photosensitizer from being too small and releasing directly into the tissue fluid from the eluted small pores,thus avoiding certain side effects.At the same time,the up-conversion particles were used to adjust the excitation wavelength from the usual visible light to the near infrared,which increased the light penetration and was beneficial to the treatment of deep infection.Due to the combination of this design of the fiber structure with the good adhesion of the in-situ electrospinning,the reactive oxygen species inside the fiber quickly escape to the fiber surface and quickly transport to the wound that is closely attached to the fiber membrane.Therefore,after rapid hemostasis,the one-stop service of photodynamic killing of multidrug-resistant bacteria can promote collagen regeneration,reducing the wound healing time from 24 days to 16 days.This kind of multifunctional composite nanofiber prepared by in-situ electrospinning has achieved remarkable results and provides a new choice for our biological medicine.