Preparation And Application Of PVB-based Janus Dual-layer Wound Dressing

Excessive wound exudate is one of the causes of delayed healing of diabetic wounds.Janus wound dressings,which have asymmetric hydrophilic-hydrophobic properties,can effectively manage excessive wound exudate.Electrospinning is one of the simplest techniques for preparing Janus wound dressings,by preparing a dual-layer structure with one hydrophilic and one hydrophobic layer,and combining them to form a Janus membrane.The solvents required for electrospinning materials are toxic,such as dimethylformamide(DMF)for dissolving polyurethane(PU),which may affect the health of patients and are also not environmentally friendly.Therefore,The study chose polyvinyl butyral(PVB)as the electrospinning material,which has good biocompatibility and dissolves in ethanol,creating conditions for green electrospinning.The study used electrospun PVB nanofiber membranes as the hydrophobic layer of Janus dual-layer wound dressings,and nonwoven fabrics as the hydrophilic layer of Janus dual-layer wound dressings,and prepared PVBbased nanofiber membrane Janus dual-layer wound dressings by combining them.At the same time The study found a simple water treatment method to construct water channels in the hydrophobic layer that can transport excess exudate from bottom to top through the hydrophobic layer to the hydrophilic layer,where it is absorbed by the hydrophilic layer and does not flow back into the wound.The study prepared a series of Janus dual-layer wound dressings with different fiber densities in the hydrophobic layer by controlling spinning time and demonstrated their excellent unidirectional fluid transport capability.Another important reason for difficult healing of diabetic wounds is immune dysregulation in wounds.Wound healing has four stages: hemostasis phase,inflammatory phase,proliferative phase and remodeling phase.Macroscopically speaking,diabetic wounds are chronically inflamed due to bacterial infection and low immune regulation ability and fail to enter proliferative phase and remodeling phase resulting in delayed wound healing.From a cellular perspective macrophages involved in immune regulation express pro-inflammatory M1 phenotype for a long time without transforming into antiinflammatory M2 phenotype making wounds difficult to heal.In treatment of diabetic wounds antibiotic abuse easily causes bacteria to develop drug resistance form biofilms and cause chronic inflammation in wounds.It has been reported that currently methods based on immune regulation for treating diabetic wounds have attracted researchers’ attention because they do not produce drug resistance and are harmless to human body some bioactive substances are added to wound dressings for promoting immune regulation in wounds making M1 cells transform into M2 cells thereby promoting wound healing.The study loaded quercetin as an immune-regulating component for diabetic wounds into Janus duallayer wound dressings simply put quercetin was co-electrospun with PVB solution making it loaded into PVB nanofiber membranes.The study prepared a series of Janus dual-layer wound dressings with different amounts of quercetin loading which proved successful loading of quercetin shortened wound healing process proved macrophage M1 phenotype transformation into M2 phenotype proving Janus dual-layer wound dressing’s immuneregulating ability.