Preparation And Properties Of Lignin-based Wound Dressing

As for tissue engineering biomaterial in-depth study on the level of cells,and the healing process of wound recovery process has a clear understanding,found that has a single function of dressings have been unable to meet the needs of different types of wound repair,development performance more superior composite dressings is the research hotspot in the field of biological materials.Lignin is the main component of plant cell walls and the second most abundant macromolecule on earth after cellulose.However,only about 2% of the lignin is effectively used(the paper industry produces about 70 million tons of lignin annually),and the rest is burned as a low-grade fuel.Lignin is an amorphous biological macromolecule,a three-dimensional structure formed by connecting various phenylpropanes through ether bonds or C-C bonds.In addition,lignin also contains a large number of active groups,including phenolic hydroxyl,hydroxyl and sulfonic acid groups.Due to the presence of these functional structures and groups,lignin exhibits good antioxidant activity,free radical scavenging,impact resistance and tensile properties.Lignin can effectively improve the structural strength of plant cells and resist the invasion of adverse environments.The special chemical properties of lignin make it have a special effect on wound healing.Therefore,it is of great significance to introduce lignin into the hydrogel applied to the wound surface as a suitable raw material for wound dressing.Inspired by trees.Trees are made of cellulose,hemicellulose and lignin connected by covalent bonds and supramolecular bonds.Among them,lignin with a three-dimensional structure plays a role in increasing strength and supporting the structure of trees.This thesis combines three kinds of lignin-based composite wound dressings based on the biological activity of lignin and the functional requirements during wound recovery:Among them,the nanofiber membrane is the only method for producing continuous fibers on the microscale or nanoscale.The material has high flexibility,low cost and is very attractive.In addition,the high specific surface area and porosity ensure that nanofibers can promote cell adhesion and oxygen transport,which can achieve moisturizing,exudate removal and hemostatic effects,which is beneficial to skin regeneration.Therefore,we have established a double-layer nanofiber membrane with directional water absorption and water retention,which can improve the antibacterial performance of the wound dressing model by combining ionic liquids with high efficiency and repeated antibacterial properties,and by absorbing tissue fluid and adsorbing proteins The model test verified that the nanofiber has potential application value in wound debridement.In addition,hydrogel is a potential wound dressing because of its unique properties such as good flexibility,elasticity,biocompatibility,high water content and sensitivity to physiological environment.However,due to the poor antibacterial activity of hydrogels and insufficient mechanical strength,their applications are often limited.The general polyvinyl alcohol-chitosan composite hydrogel has good biocompatibility and antibacterial ability,but its mechanical strength is poor,which limits its application in medical dressings.The most important thing is that the general polyvinyl alcohol-chitosan composite hydrogel cannot meet the requirements of wound dressing as an environmental regulator to accelerate wound healing.In this paper,a novel lignin-chitosan-PVA composite hydrogel was prepared as a wound dressing by freeze-thaw cycle one-pot method.The introduction of lignin effectively improved the hydrogel's mechanical strength(tensile stress up to 46.87 MPa),protein adsorption capacity and wound environment regulation capacity.In the mouse wound model,the lignin-chitosan-PVA composite hydrogel significantly accelerated wound healing.The developed hydrogel provides new opportunities for efficient skin wound care and management.Finally,we designed a hydrogel wound dressing with different orientations to cope with the existing hydrogel dressing that does not match well with irregular depth burn wounds,nor can it reach certain special parts,such as joints Wound surface and hollow wound surface.This paper designed a new type of self-healing hydrogel.In this hydrogel,the intermediates of acetylated lignin and ILs(ionic liquids)form covalent crosslinks with HEMA(2-hydroxyethyl methacrylate)by free radical polymerization.During the formation of hydrogels,reversible hydrogen bonds generally exist between lignin monomers and HEMA,forming physical and chemical double-network cross-linked hydrogels.Therefore,the hydrogel can not only withstand large deformation,but also maintain elasticity.Reversible interactions including hydrogen bonding and dynamic covalent crosslinking can make the hydrogel self-healing efficiently without external stimuli.The introduction of ILs and lignin effectively controls the hydrogel's ability to adsorb proteins and mechanical strength,thereby better removing metabolites and resisting external reinjury.The hydrogel of lignin-ionic liquid-HEMA double network structure has the characteristics of self-healing,contact antibacterial and anti-fatigue,which can be reused,reducing waste and reducing medical cost.