| As a human body barrier,skin can protect internal organs,regulate temperature and prevent body fluid loss.When the skin is damaged,external pathogens and microorganisms can easily invade the human body,increase scar formation,and even inhibit the healing process,affecting the health of patients.Therefore,when the skin is damaged,it is important to use wound dressing to reconstruct the structure and function of the skin as soon as possible.However,many problems such as airtight or weak resistance to bacterial infection,wound mismatch and poor mechanical properties are difficult to be solved at the same time.From the perspective of clinical application,it is of great significance to develop a functional wound dressing that can resist external bacteria and microorganisms,absorb wound exudate and have good air permeability,moisture retention and antibacterial activity.This paper focuses on the above problems,imitates the natural structure of skin,studies and prepares a wound dressing with good air permeability and antibacterial properties.Firstly,chitosan（CS）/Laponite（Lap）composite scaffold prepared by frozen 3D printing was used as the base layer of asymmetric dressing and its properties were explored and optimized.CS/Lap scaffolds with different Lap contents were prepared.The macroscopic and microscopic morphology of the scaffolds were observed,and the phase structure of the scaffold was analyzed by XRD and FT-IR.The mechanical properties,porosity,swelling,moisture retention and cytotoxicity of the scaffolds were comparatively studied.It was found that the porosity of CS/Lap scaffolds prepared by3D printing reached more than 90%.In addition,it was found that the mechanical properties and moisture retention capacity of the scaffolds increased by 18-63%and 7-56%,respectively,after the addition of Lap.These characteristics will improve the comfort of patients and create a wet wound healing environment.Combined with the results of cytotoxicity tests,the scaffold with 5 wt%Lap was selected as the underlayer of the asymmetric dressing.Then,on the scaffold selected in the previous part,hydrophobic PCL fiber membrane prepared by electrostatic spinning was used as the top layer of the dressing,and copper ion was mixed into the bottom scaffold as antibacterial agent to form an asymmetric dressing with antibacterial function.SEM was used to observe the microstructure of the upper and lower layers of the asymmetric dressing,and it was found that the dressing had a structure combining large pores and small pores.Cell migration,cytotoxicity,antibacterial and in vitro wound healing experiments were carried out,and it was found that asymmetric wetting dressing structure showed good ability to promote cell migration and anti-microbial permeability.In vivo experiment results showed that asymmetric wetting of copper doped CS/Lap-PCL dressing significantly shortened the wound healing time,the wound healing area reached about98.24%on day 12th.A functional asymmetric dressing incorporating dexamethasone（DEX）/β-cyclodextrin（β-CD）inclusion complex was developed to treat pathological lesions of the skin,such as allergy-induced specific dermatitis.The inclusion complex was prepared by coprecipitation method to improve the water solubility,stability and sustained release of drugs.The inclusion complex was successfully prepared by SEM and FT-IR.Subsequently,DEX andβ-CD were verified to be 1:1 according to the inclusion principle.The sustained release effect of inclusion complex mixed into CS5scaffold was tested.It was found that the drug delivery mode combined with inclusion complex and scaffold was conducive to the stable release of drugs,and the release of DEX-CS,DEX-CS5 and IC-CS5 was about 98.34%,75.11%and 56.31%within 48 h,respectively.Combining the results of the previous two parts,we can expect that the combination of DEX/β-CD inclusion complex and asymmetric dressing CS5-PCL will have a good application prospect in the treatment of specific dermatitis. |
PDF Full Text Request