Preparation And Characterization Of Collagen/Chitosan Composite Antibacterial Wound Dressing

Skin plays an important role in maintaining the normal physiological function of the human body.But it’s vulnerable to internal or external injuries in daily life.There are various wounds such as burns,cuts and various chronic wounds such as limb ulcers,diabetic foot and so on.At this time,the use of ideal wound dressing will promote wound healing process.The choice of an ideal wound dressing for wound healing is of great significance.The new type wound dressing has many advantages compared with the traditional wound dressing,such as to maintain the wound moist.But most of these wound dressings have a single function and can’t promote the comprehensive role in wound healing.In this study,we discarded the drawbacks of traditional wound dressings and developed a next generation of functional wound dressing with antibacterial and hemostatic effects based on new wound dressings.Collagen（Col）has excellent biological properties such as biocompatibility,biodegradability and hemostasis.It has been proved that collagen can promote wound healing,which is an ideal material to be developed into the next generation of functional wound dressing.However,the application of collagen is limited due to its low mechanical strength,susceptibility to infection and disorganization.Chitosan（CS）has excellent biocompatibility,antibacterial property and biodegradability.Chitosan can be blended well with collagen,and it’s rigid chain structure can enhance the mechanical strength of blend nanofibrous membrane which has broad application in wound dressing field.Polyethylene oxide（PEO）has good biocompatibility.Its flexible chain structure can increase the entanglement between molecular chains therefore it is a kind of common spinning agent in electrospinning process.Electrospinning nanofibrous membrane of collagen and chitosan has biomimetic structure,which can simulate the structure and function of natural extracellular matrix.In addition,the blended nanofibrous membrane has excellent mechanical strength,antibacterial property and coagulation property,and it has potential applications in the field of wound dressing.In this study,a new mixed solvent is proposed for the first time as a mixture of hexafluoroisopropanol（HFIP）,acetic acid（AA）,and deionized water（H₂O）.Collagen,Chitosan and PEO were dissolved in HFIP/AA/H₂O mixture（v/v,50/40/10）with the weight ratio of 80:0:20,65:15:20,40:40:20,15:65:20 and 0:80:20,the concentration was 3 wt% and the content of PEO was fixed at 20%.The voltage of electrospinning was 18 k V,the flow rate was 1.0 m L/h and the distance from the needle tip to the collecting board was 22 cm.Nanofiber made from spinning solution has favorable morphology.Nanofibers morphology,mechanical strength,chemical property,thermal property,stability,antibacterial property and blood related properties were characterized to study the influence of collagen and chitosan on the nanofibrous membrane properties.With the ratio of chitosan increase from 0 to 80%,the tensile strength increase from 1.85 ± 0.15 MPa to 4.19 ± 0.85 MPa,which is higher than the tensile strength of pure collagen nanofibrous membrane.The DSC and FTIR results indicated that interactions exist in Col/CS blended nanofibrous membrane.As to the stability of morphology,nanofibrous membrane were soaked in PBS for 24 hours first,and then the morphology of nanofibers was observed by SEM.The results show that with the increase of chitosan ratio,morphology stability is gradually improved.Both qualitative and quantitative antimicrobial test are used to characterize the antibacterial properties of blended membrane.It can be concluded that collagen can promote propagation of bacterial.The addition of chitosan can provide antibacterial property to the blended membrane.With the content of chitosan increase,the inhibition rate increased from 50-56% to 94-95%.The blood compatibility of blended membrane is studied by hemolysis test,thrombotest and platelet adhesion test.The result shows that all of these five different kinds of nanofibers membrane have remarkable blood compatibility.From the results of thrimbotest and platelet adhesion test,it can be indicated that collagen plays a more important role in blood coagulation than chitosan.Besides,the structure integrity of blended membrane has an effect on the coagulation property.Blended membrane with higher collagen content will swelled and degraded,and the structure is damaged seriously,which is not conducive to platelet adhesion and coagulation.With the content of chitosan increase,the structure of blended nanofibrous membrane turns good.The coagulation properties of collagen and chitosan synergized,which cause the coagulation index decrease first and then increase.In conclusion,chitosan plays an important role in improving the mechanical property,morphology stability and antibacterial property of blended membranes.In contrast,the increase of collagen content is more beneficial to the improvement of coagulation and platelet adhesion.All of these take into account,when the content of collagen/chitosan/PEO is 15:65:20,the blended membrane has better comprehensive performance.