Portable direct spraying porous nanofibrous membranes stent-loaded polymyxin B for treating diabetic wounds with difficult-to-heal gram-negative bacterial infections.

Gram-negative bacteria infections in diabetic wounds are complicated to control, leading to amputation and even death in severe cases. There is an urgent need to develop effective therapeutic strategies. In recent years, electrospinning has attracted much attention due to its resemblance to extracellular matrix (ECM), which can regulate local cellular proliferation, migration, differentiation, etc.; however, its use is limited by its high cost and difficulty in transportation. This study proposes a portable direct-injection porous fibre scaffold containing polymyxin B (PMB) for local slow release for treating diabetic wounds infected with difficult-to-heal Gram-negative bacteria. The handheld portable electrospinner is lightweight and easy to operate and can be directly sprayed in situ to cover wounds with irregular shapes and sizes. When covering the wound in situ, the PVB/PVP nanofiber membrane can protect it from the external environment. Meanwhile, the nanofiber membrane dressing has a porosity of 20 % and a controlled drug-loading capacity. What's more, the evaluation of a whole skin defect model of type II diabetes mellitus infected with Gram-negative bacteria showed that the PMB-loaded nanofiber membrane could effectively inhibit Gram-negative bacteria infection, promote collagen deposition and re-epithelialization, and regulate the polarization of M1-type macrophages to M2-type macrophages, thereby controlling inflammation and promoting vascular regeneration, and significantly accelerating the healing of diabetic wounds. Overall, portable direct-injection porous fibre scaffold-loaded drugs are essential for healing difficult-to-heal wounds as local slow-release drug delivery.