Preparation And Characterization Of Composite Materials Based On Oxidized Sodium Alginate And Calcium Phosphate

With the development of current minimally invasive surgery,injectable bone repair materials have gradually become a research hotspot.The injectable bone repair material has excellent injectability,can be shaped freely at the repair site and selfsolidifies in situ,and has good bone conductivity and biocompatibility,which can provide mechanical or biological functions.Injectable bone repair materials have great potential for development in clinical applications.Therefore,this work aimed at the current two types of injection-type bone repair materials(calcium phosphate bone cement and hydrogel system),and improved the functionality of the material system through component modification,as follows:In view of the characteristics of calcium phosphate bone cement(CPC)with poor anti-washout property and weak bone adhesion,this study modified the anti-washout property and bone adhesion of CPC by adding oxidized sodium alginate(OSA).The modified CPC was investigated for its anti-washout property,bone adhesion,injectability,setting time,diameter change rate,compressive strength,solidified phase,micro-morphology and other physical and chemical properties,and its anti-washout property and the adhesion mechanism was discussed.The results showed that the aldehyde groups in OSA reacted with the amino groups in the tissues during the CPC hydration process under the action of self-adjusting p H value,making the modified CPC have good tissue adhesion.The results of the push-out test showed that the addition of 6wt% OSA can increase the tissue adhesion of CPC from 6.42±0.76 N in the control group to 61.50±4.09 N.In addition,the addition of OSA did not show a significant negative impact on the mechanical properties of CPC.CPC modified by OSA is expected to broaden the scope of use of bone cement.Organic-inorganic composite injection-type hydrogel materials have been extensively studied.In order to expand the application of injectable hydrogel materials,we prepared an adhesive hydrogel with antibacterial properties(OSAGelDA@ACP/DA/Ag)in this work.First,we used polydopamine coating to deposit elemental silver on the surface of amorphous calcium phosphate(ACP)particles to prepare ACP/DA/Ag particles.Next,dopamine was grafted on the gelatin molecular chain with EDC/NHS to activate the carboxyl group to obtain dopamine-modified gelatin(GelDA).The content of DA in GelDA was about 14.09% by standard curve method.Then,using the Schiff base reaction between the amino group on the GelDA molecular chain and the aldehyde group on the OSA molecular chain,an OSA-GelDA adhesive hydrogel was prepared.Finally,by changing the amounts of ACP/DA/Ag3 particles added to the OSA-GelDA hydrogel,the effect on the performance of the adhesive hydrogel was investigated.The results showed that the introduction of dopamine provided wet adhesion to the hydrogel,and the ACP/DA/Ag3 particles introduced into the adhesive hydrogel provided antibacterial properties.This antibacterial and wet adhesion hydrogel is expected to become an injectable bone repair material for clinical use.In summary,in this work,we used OSA as the key material component to prepare and characterize two types of injectable bone repair materials: one type was a modified calcium phosphate bone cement material that is mainly composed of an inorganic phase,the other type was hydrogel injection material with organic phase as the main component.And through material modification,it gave the material system tissue adhesion and other properties.The development of this work will help to explore the preparation of new organic-inorganic materials and related functional improvements;and hope that its basic research will serve as a reference for the preparation of composite bone repair material systems and related mechanisms.