Preparation And Properties Of Chitosan Microsphere Composite PVA/SA Hydrogel Sustained Release Scaffold

There is no blood vessels,lymphatic vessels,or nerves in the articular cartilage,so its own repair capacity is limited.The use of cartilage repair growth factors can promote cartilage repair.However,the half-life of growth factor is short,it will be quickly metabolized in vivo,and it can not fully function.Therefore,how to control the slow release of cartilage repair growth factor has become a problem to be solved.In the biomedical field,extensive research has been conducted on biodegradable microspheres and hydrogels.Microspheres have been reported as an important part of drug delivery systems,such as polylactide-glycolic acid copolymer microspheres and seaweeds.The sustained release effect of sodium microspheres and liposome microspheres can not only maintain the effective concentration of the drug,but also prolong the drug release time,increase the bioavailability of the drug,and can also reduce the toxic and side effects caused by sudden drug release.The use of hydrogels in the field of drug release is also common.In recent years,injectable hydrogels have been widely used as drug carriers and cell scaffolds because of their good biocompatibility,porous structure and adjustable elastic shape.Therefore,three biomaterials,biocompatible,biodegradable,chitosan,sodium alginate,and polyvinyl alcohol,were chosen to meet the requirements of biosafety,non-toxic,and side effects of drug release stents.The three materials are widely used in biological sustained-release stents,and complement each other in some properties,providing a good prerequisite for the development of controlled-release stents with excellent performance and excellent performance.This article will be embedded BSACMs embedded in polyvinyl alcohol / sodium alginate hydrogel to form a composite three-dimensional sustained-release stent,hoping to effectively reduce the sudden release of drugs,have a good sustained release rate,to meet the cartilage repair requirements.In this paper,CMs were prepared by emulsion cross-linking method and freeze-thaw cycle method prepared four kinds of ratio of the composite hydrogel and embedded BSACMs embedded in polyvinyl alcohol / sodium alginate hydrogel to form a composite three-dimensional sustained-release stent.In the preparation of CMs,the BSA model protein was used as a sustained-release drug,and the effects of the rate of colostrum emulsificationand the rate of cross-linking of the cross-linking agent on the structure,morphology and various properties of the microspheres were further studied,and then the best ball formation was obtained.Process.The morphology of the microspheres,the four proportioned hydrogels and the composite scaffolds and the particle size of the microspheres were observed by scanning electron microscopy.The biomechanical properties of the hydrogels and composite scaffolds were measured using a compression elastic strain test and oscillated in a constant temperature water bath.The swelling properties of hydrogels and composite scaffolds were studied.The drug loading and entrapment efficiency of BSA microspheres were determined by ultraviolet absorption spectroscopy.The in vitro degradation and drug release of microspheres,hydrogels and composite scaffolds were compared.behavior.The antibacterial properties of microspheres,four kinds of proportional hydrogels and composite stents were studied,and a preliminary exploration was made for its application as a cartilage slow-release dressing.The CMs(CMs)prepared by the emulsion cross-linking method have a complete spherical shape,a smooth surface,and a uniform size.The four kinds of gels with uniform proportions were prepared.The higher the proportion of PVA was,the smaller the pores and the tighter the structure.The larger the ratio of SA gel,the more the pores and the looser structure.In the scanning electron microscopy image,the CMs were successfully encapsulated in Gel and remained in a spherical shape.The concentration of CMs encapsulated in Gel was different,and the morphology of CMs/Gel was also different.In the degradation experiment,it was observed that the gel containing the greater proportion of PVA degraded faster,and the gel containing more SA components degraded more slowly,indicating that PVA was more biodegradable than SA.Composite scaffolds degrade slower than single gels.The greater the proportion of CMs in composite scaffolds,the faster the degradation.This is because CMs are more degradable than gels.It was found that the larger the PVA component contained in the gel was,the smaller the water absorbency was,and the larger the SA component was,the greater the water absorbency was,indicating that SA had better water absorbency than PVA.Composite scaffolds had poorer water absorption than single gels,and the larger the proportion of encapsulated CMs was,the slower the swelling balance was,and the swelling rate was also smaller,indicatingthat CMs were less absorbent than gels.No matter whether the burst release of single CMs or composite stents is not obvious at 2h~2d,it is expected to be a scaffold for drug sustained-release delivery.The loading of CMs in Gel showed that the release of drug was slower,and the smaller the concentration of CMs was,the slower the release was.The larger the proportion of PVA in the gel,the better the compression performance;the smaller the SA ratio,the worse the compression performance,and the composite stent has better compression performance than the single gel.In this experiment,BSACMs were successfully prepared.The particle size of the microspheres was mainly distributed between 5 and 38 μm,the microsphere drug loading was 31.03%,and the encapsulation efficiency was46.77%.The BSACMs contained 98% of the drug release 14 days after the drug release test.The release of CMs was not obvious during the initial release from 2h to 2d.The release rate gradually increased in the following week.The cumulative release on the second day was about 36%,and the cumulative release on the fifth day was about 80%.The cumulative release of BSA on the 14 th day.About 98%.After release of Gel and CMs/Gel in vitro for14 days,the drug release rates were 30 to 40% and 30 to 60%,respectively.Loading drug-loaded CMs on Gel can greatly reduce the in vitro release rate and achieve better sustained release efficiency.Therefore,this article provides experimental basis for the clinical study of the preparation of protein drug long-acting agents.The antibacterial properties of CMs make a preliminary exploration of their application as wound dressings.The PVA/SA composite hydrogel made in this paper is exactly complementary in structure and performance,making up for the defects when used alone.Composite stents are superior to microspheres and hydrogels alone in terms of mechanical properties,swelling properties,structure and sustained release.They can meet the mechanical strength,elasticity,biodegradability,and biologic phases required for clinical cartilage tissue engineering scaffolds.Capacitive and sustained-release effects can be a good drug release stent.This article lays a foundation for the follow-up study of chondrogenic growth factor before and after clinical work.It is hoped that the composite stent prepared in this paper can be an ideal drug release material for stents.