Exploration And Properties Of Wound Dressings Based On Nanofiber Materials

Skin is a physiological barrier between human body and the external environment,consisting of connective tissue,nerve tissue,muscle tissue and epidermal tissue,and plays a variety of functions such as sensation,absorption,immunity and so on.The injury of skin damage its integrity,then wound infection,delayed healing and complication may happens,which are very unfavorable for our body to maintain normal physiological activities.Wound healing is a complex and dynamic process.Accelerating wound healing largely depends on whether an optimal healing environment can be provided for the wound.Thus,wound dressing plays a vital role in wound healing management.The unique structure of nanofibers and their functionalized materials can meet the requirements of ideal dressings.Therefore,in this study,a functional dressing with a composite structure was prepared based on electrospun nanofibers and bacterial cellulose nanofibers.The healing-promoting layer and the protective layer were prepared respectively,and their properties and structures were analyzed in this work,mainly including:(1)Electrospinning technology was employed to prepare curcumin(CUR)loaded PCL/Gelatin nanofibers(CUR-F2,CUR-F4,CUR-F6)by blending polycaprolactone(PCL)and gelatin in different mass ratios(8:2,6:4,4:6).The morphology,crystallinity and thermal stability of the nanofiber membranes were characterized,and their water uptake capabilities,water vapor transmission rate,curcumin release behaviors and antioxidant properties were tested and analyzed.Curcumin was anti-inflammatory,anti-oxidant and could accelerate wound healing,but its crystallinity was high and solubility was poor.X-ray diffraction and differential scanning calorimetry curves showed that curcumin in the nanofiber membranes was amorphousn after electrospinning.The water uptake capabilities of the fiber membrane was positively correlated with the gelatin content and the water vapor transmission rate showed a slight downward trend as the proportion of gelatin increased.Vitro drug release experiment and antioxidant test showed that the cumulative release rate and free radical scavenging rate went up with the increase of the proportion of gelatin in the fiber membrane.The release behaviors of curcumin was analyzed by fitting zero-order,first-order,Higuchi and Ritger-Peppas drug release mathematical models.The drug release curves of the drug-loaded fiber membranes have the highest fitting coefficients to the first-order release kinetic equation,and the drug release behaviors conforms to the Fick diffusion mechanism according to Ritger-peppas fitting model.When the mass ratio of polycaprolactone and gelatin was 6:4,CUR-F4's comprehensive performance was more suitable to be a healing promoting layer.(2)Bacterial cellulose(BC)was prepared by biological culture at first,then BC-ZnO fiber membranes(BZM1?BZM3?BZM10)loaded with different contents of ZnO were obtained by hydrothermal synthesis at various concentration of zinc sulfate(0.01 mol/L?0.03 mol/L?0.10 mol/L)to impart antibacterial properties to the bacterial cellulose.Their morphology,crystallinity,thermal stability,water uptake capabilities,water vapor transmission,mechanical properties and antibacterial properties were characterized and analyzed.SEM observation revealed that the zinc oxide with rod-shaped and agglomerated shapes was distributed on the bacterial cellulose.The loadings of ZnO increased as the concentration of zinc sulfate went up according to ICP test.The addition of ZnO reduced the membranes' water uptake capabilities,but had less effects on water vapor transmission.The better antibacterial properties against Staphylococcus aureus and Escherichia coli were obtained when more ZnO loaded on BC.BZM3 parpred under a relative low zinc sulfate concentration,had good antibacterial activity,water uptake capability,water vapor transmission and mechanical properties,so it was suitable to be a protive layer.(3)The healing layer(CUR-F4),set as the inner layer,was placed obove the protective layer(BZM3),which was set as the outer layer.The two layers were pressed at 45?,then the composites was constructed and its properties were tested.The composites' water uptake capabilities,water vapor transmission was compared with several commercial dressings.The results showed that the water uptake capabilities and water vapor transmission of the composites was smaller than BZM3,but had advantages over some commercial dressings.The cell compatibility of the healing layer were evaluated by CCK-8 assay,which showed that L929 cells still maintained high relative activity after 24 h and 72 h treatment.The test result indicated that the composites has the potential to be a medical dressing.In summary,this study was based on two kinds of nanofiber materials to construct a functional wound dressing with a composite structure.The inner layer was electrospun nanofibers which could release curcumin and had good cell compatibility.The outer layer was bacterial cellulose loaded with zinc oxide which could prevents wound infections caused by microbial growth.The preparation and investigation of the functional dressing with a composite structure provided a reference and idea for wound management.