Preparation Of Modified Chitosan/Cellulose Ether Composite Antibacterial Film For Wound Repair

Injured skin is easy to cause wound infection and inflammation,while excessive use of antibiotics will lead to bacterial resistance.In order to accelerate wound healing and reduce the probability of inflammation,it is a new choice to cover the wound with skin wound repair dressing as a temporary substitute for skin to protect the wound site and accelerate wound repair.Chitosan(CS)is the deacetylated product of a natural biopolymer chitin,which has a variety of biological activities such as good biocompatibility,biodegradability,anti-infection,antibacterial,hemostasis and healing,anti-adhesion,scar reduction,enhancement of immunity and anti-tumor.Cellulose ether films have good mechanical properties.Aiming at the infection of skin wound,this research plans to take chitosan as the main raw material to blend cellulose ether(HPC,HEC)and chitosan for the preparation of antibacterial film by delayed flow method.And use sodium trimetaphosphate(STMP)to crosslink it to prepare a modified chitosan/cellulose ether composite antibacterial film.The specific research is as follows:The optimum mass proportion of chitosan/cellulose ether composite antibacterial film was studied.Using chitosan and two kinds of cellulose ether as raw materials,and the chitosan/cellulose ether composite antibacterial film was prepared by the delayed flow method.The optimum proportion of chitosan/hydroxyethyl cellulose ether composite antibacterial film(HECS)is 1:1,the optimum proportion of chitosan/hydroxypropyl cellulose ether composite antibacterial film(HPCS)is 1:1,and the optimum proportion of chitosan/hydroxyethyl cellulose/hydroxypropyl cellulose ether composite antibacterial film(HEPCS)is 2:1:1.Then the composite film was modified by STMP.Taking the size of the bacteriostatic ring of the composite film against the growth of Escherichia coli as the evaluation index,the response surface method was used to determine the optimal preparation conditions of the modified chitosan/hydroxyethyl cellulose ether composite antibacterial film(CHECS): HEC mass ratio was 45%,STMP concentration was 0.17%,and crosslinking time was 1.5 h.The optimum preparation conditions of modified chitosan/hydroxypropyl cellulose ether composite antibacterial film(CHPCS)were as follows: HPC mass ratio was 45%,STMP concentration was 0.18%,and crosslinking time was 1.9 h.The optimum preparation conditions of modified chitosan/hydroxyethyl cellulose/hydroxypropyl cellulose ether composite antibacterial film(CHEPCS)are as follows: the mass ratio of CS is 50%,the mass fraction of HEC is 25%,the mass fraction of HPC is 0.21%,the concentration of STMP is 1.9h.The antibacterial film has been proven to have a certain inhibitory effect on bacterial growth.And HEC has a promoting effect on the antibacterial properties of the membrane.STMP crosslinking also enhances the antibacterial properties of the membrane.FTIR,XRD,and TG characterizations indicate that there was only a physical blending between CS and cellulose ether before modification.Each molecule retains its own functional group and functions accordingly.The intermolecular hydrogen bonding promotes an increase in fracture elongation.STMP connects CS and cellulose ether together through phosphate diester bonds,further enhancing the mechanical properties of the antibacterial film.SEM characterization indicates that the components of the antibacterial film have good compatibilities and smooth surfaces,which are suitable for use as wound dressings.The introduction of cellulose ether enhances the swelling and degradability of the film,which is beneficial for its absorption of wound tissue exudate and improves its safety for human skin.Crosslinking improves the compatibility of each component,but it also reduces the degradability of the film.This is also the only drawback caused by cross-linking.In terms of water vapor permeability,cross-linking enables the antibacterial film to provide a better humid environment,and all six membranes meet the pharmaceutical industry standards and the normal range of water vapor permeability of human skin,effectively inhibiting wound water loss.In terms of cytotoxicity,HECS membrane and CHECS membrane undoubtedly perform the best,all of which meet the cytotoxicity requirements of medical materials and have a promoting effect on cell growth.It was verified that chitosan can inhibit the inflammatory reaction caused by wound infection bacteria and promote wound repair and healing on mouse skin wounds.At the same time,cross-linking can strengthen these effects.The overall effect of the film containing HEC is better than that of the film containing HPC.It may be that HEC has the physical hemostatic function and can provide an ideal environment for the wound to promote granulation of the wound tissue and autolysis debridement.