Preparation And Performance Study Of Cellulose-Based Medical Textile Wound Dressings

With the frequent appearance of accidents and the development of global aging,wound management has gradually become an important factor threatening human health.According to the length of healing time,wounds can be divided into acute wounds and chronic wounds.Usually,acute wounds can heal without other interventions,the key is to stop bleeding in time.While the chronic wounds caused by an underlying pathological process often take a longer time to show the progress of healing,and the key is to end the vicious inflammatory cycle.Cotton gauze is the most used dressing in clinic,but it has poor hemostatic performance,antibacterial and wound healing properties.Carboxymethylation modification is an important method to enhance the hemostatic performance of cotton fabric-based wound dressing,but the current research on the relationship between the degree of modification and hemostatic performance of carboxymethylated cotton fabric is not comprehensive,and fabric-based wound dressing is difficult to provide moist environment that is beneficial to wound healing.Based on this,starting from the mechanism of acute and chronic wound healing,the carboxymethylated cotton fabric was prepared and its hemostatic performance was explored,furthermore,composite hemostatic textile dressing based carboxymethylated cotton fabric was designed and prepared for acute and chronic wound healing.The main research contents and conclusions are as follows.(1)Preparation and properties of carboxymethylated cotton fabric as hemostatic wound dressingThe cotton fabric(CF)was carboxymethylated using monochloroacetic acid,and the carboxymethyl content in carboxymethylated cotton fabric(MCF)increased with the increasing amount of monochloroacetic acid.During the modification process,the crystal of cellulose in the fabric was changed from type Ⅰ to type Ⅱ,the thermal stability decreased slightly,and the surface fracture increased slightly.The swelling property of the MCF was better than that of CF,wet MCF showed colloidal surface,and its fibrous boundary was blurred.MCF with good biocompatibility could increase the viscosity of body fluid,and promote the aggregation of blood cells.In the rat liver injury model,the bleeding time in the group using MCF was shortened by 47.52% than the group using CF.(2)Design and preparation of asymmetric hemostatic wound dressing based on carboxymethylated cotton fabricTo solve the problem that pure cotton fabric absorbs excessive blood and easily leads to unnecessary blood loss,an asymmetric hemostatic Janus wound dressing based on carboxymethylated cotton fabric was designed and prepared for the situation of massive acute bleeding.One side of Janus wound dressing was hydrophilic with the water contact angle of 0°,where carboxymethyl chitosan was compounded onto the surface of MCF through the spray freeze-drying method.The other side of Janus wound dressing was combined with paraffin to prepare a hydrophobic surface with a water contact angle of 152° by the spray drying method.The hydrophilic surface of Janus wound dressing with good water absorption property could promote the aggregation of blood cells.Meantime,the hydrophobic surface can prevent excessive absorption of blood.To test the hemostatic properties of Janus wound dressing in vivo,the rat liver injury model was used to simulate the situation of normal bleeding,and the rat carotid artery injury model was created to represent the situation of massive acute bleeding.Here,Janus wound dressing significantly reduced the hemostatic time and blood loss compared with CF in the rat liver injury model,and the group using Janus wound dressing in the rat carotid artery injury model significantly prolonged the survival time compared with the group using CF.As a novel hemostatic wound dressing,Janus wound dressing has broad application prospects in prehospital care for rapid hemostasis,which can provide more rescue time for patients with acute massive haemorrhage.(3)Design and preparation of carboxymethyl cellulose-based hydrogel wound dressingDuring the healing process of chronic wounds such as diabetic wounds,the excessive secretion of reactive oxygen species is one of the important reasons leading to the vicious inflammatory cycle.Melatonin(MT)is a well-known antioxidant,but its poor solubility limits its use in many fields.In this study,the γ-cyclodextrin(γ-CD)with special structure that is internally hydrophobic and externally hydrophilic was introduced to form the composite named MT-γ-CD with MT for the purpose of improving the solubility of MT.The preparation method is ultrasonic method.The obtained MT-γ-CD showed excellent antioxidant properties in vitro.The free radical scavenging efficiencies of MT-γ-CD were more than 90% in both ethanol and PBS solution.To load MT-γ-CD,an injectable self-healing hydrogel was prepared.Firstly,sodium carboxymethyl cellulose was oxidized to obtain oxidized sodium carboxymethyl cellulose with aldehyde groups.The aldehyde groups from oxidized sodium carboxymethyl cellulose could form Schiff base with amino groups in gelatin.The hydrogel combined with MT-γ-CD had good biocompatibility.It could be injected into irregular wounds,provide a moist environment that is conducive to wound healing,and inhibit the level of reactive oxygen species at the wound site to promote the healing of diabetic wounds.Therefore,this composite dressing can provide a new promising therapeutic strategy for hard-healing diabetic wounds.(4)Design and preparation of carboxymethylated cotton fabric/hydrogel-based antibacteria wound dressingFabric-based wound dressings are difficult to maintain a proper moist environment for wound healing,and some hydrogel-based wound dressings have unsatisfactory hemostatic properties and gas permeability.This study put forward the strategy of checkerboard-pattern wound dressing to prepare a composite dressing with good air permeability,hemostatic,antibacterial and healing promotion properties.Based on section(2)and(3),MCF was obtained to be the base textile at first.Secondly,oxidized sodium carboxymethyl cellulose with aldehyde groups could form Schiff base bonds with amino groups in gelatin to form hydrogel,meantime,dopamine and silver nanoparticles were introduced to prepare multifunctional hydrogels with antioxidant and antibacterial properties.The obtained multifunctional hydrogel was printed onto one side of the MCF through the method of screen printing,and the subsequent deposition of paraffin made the other side of MCF hydrophobic.Compared with hydrogels,checkerboardpattern wound dressing had better water absorption property,coagulation ability and air permeability property in vitro.In the hemostasis experiment in vivo,compared with the commonly used cotton gauze in clinic,the checkerboard-pattern wound dressing could significantly reduce the bleeding time and blood loss in rat tail,liver,and femoral artery injury models,and significantly prolong the survival time in the rat carotid artery injury model.Compared with MCF,checkerboard-pattern wound dressing showed antibacterial activity for both E.coli and S.aureus,and could promote the healing of infected wounds.Therefore,the strategy of checkerboard-pattern wound dressing is effective to prepare multi-functional dressings for hemostasis and wound healing.Also,this strategy provides a promising method for the transformation of hydrogel dressings from scientific research to clinical dressings.