Preparation And Mineralization Of Self-healing Polysaccharide Hydrogel And Its Application In Restoration Of Dental Defects

Using natural polysaccharides such as sodium alginate?SA?and chitosan?CS?as raw materials,maleic anhydride was used as a modifying agent to functionally modify chitosan to obtain a double bond content of 4582.84±28.43mol/g,The grafting rate was48.95%of maleated chitosan?CS-MA?.The carboxyl group on the alginate side chain was activated by the carbodiimide coupling agent?EDAC/NHS?.The amino group and the activated carboxyl group undergo condensation reaction to form an amide bond.The free mercapto group content is 600.8±94.52 mol/g.The branching rate was 34.85%of sulfhydryl alginate?SA-SH?.The active double bond on the side chain of CS-MA and the free sulfhydryl group on SA-SH are dissolved in water under a controlled alkaline environment of?-sodium glycerophosphate,and the Michael addition reaction occurs rapidly,resulting in in-situ formed maleic anhydride.Chitosan/sulfhydrylated sodium alginate?CS-MA/SA-SH?polysaccharide-based hydrogel,the gel formation time is not more than 15 minutes.According to SEM,swelling rate,rheometer,cytotoxicity and AO/EB experiments,the physical and chemical analysis of this hydrogel showed that CS-MA/SA-SH hydrogel not only has good mechanical properties,porous The network structure,good biocompatibility and other excellent characteristics,and the second cross-linking site can be formed due to the chelation reaction of the unique eggshell structure of the guluronic acid segment in the SA segment“G-segment”with the high-valent cations,making this The hydrogel also possesses a certain degree of self-healing properties.Through the observation of the healing interface?macro and microscopic?and mechanical strength tests,it was confirmed that the presence of calcium ions will give the CS-MA/SA-SH hydrogel system.The new ionically crosslinked network allows it to generate new chelating sites within 30 seconds to achieve rapid healing of the fracture site,healing efficiency of about 76.2%of this healing property,giving CS-MA/SA-SH hydrogel in Multi-stage plasticity characteristics in the shape:1,Michael addition molding in situ to obtain the initial shape 2,Ion cross-linking to obtain secondary shape,making the material more suitable for medical applications in the area of irregular shape defects.Through macroscopic and microscopic interface observation and compressive strength test,the self-healing ability of single crosslinked hydrogel is inferred that the rapid healing of fractures can be achieved by adding Ca²⁺in CS-MA/SA-SH hydrogel system,and the healing efficiency is about 76.2%.And this method also applies to the gel material and stent cut between the realization of gel-stent integrated materials.By using the characteristics of the hydrogel system,the hydrogel two-grade plastic properties are given:the first-order shape is given by Michael reaction chemical crosslinking in situ,and then by the ion cross-linking fixation,the two-level shape is given to better adapt to the biomedical field applications with high implant shape requirements.Secondly,through the use of a special three-dimensional network structure of hydrogels,the template of protein fiber bundles in biomineralization was simulated,with hydrogel as the“basestone”and calcium glycerophosphate?CaP?and calcium chloride as the The source of Ca²⁺and PO4^3-.In this paper,a novel"enzymatic mineralization method"is designed,which uses alkaline phosphatase?ALP?to cleave phosphate groups in CaP,and induce calcium phosphate salt deposition during biomineralization to generate phosphoric acid.The role of calcium nuclei in mineralization in vitro in hydrogels,to obtain high-purity natural biomineralization products-Hydroxyapatite?Hydroxyapatite,HAP?.In this experiment,a hydrogel containing four different concentration gradients of inorganic substances with total mass ratios of 0%,30%,50%,and 70%was set up to explore the introduction of different calcium and phosphorus salts and the mineralization time for gels.Nature and the effect of mineralization results.In the subsequent physical and chemical analysis of the first series,this mineralized hydrogel with calcium and phosphorus salts not only demonstrated the excellent properties of the original hydrogel,but also showed good biomineralization performance.The hydroxyapatite material with lamellar,petal-like and rod-like appearance has a mineralized product composition and morphology that is closer to that of natural hydroxyapatite as the mineralization time is prolonged and the concentration of the added inorganic substance is increased.It is proved that this material has a huge platform and application prospect in the repair of human hard tissue defects,and it has both the hydrogel in situ rapid prototyping performance and the potential to simulate mineralization.Finally,using the gel material obtained from the experiment,we can seal the tube by sealing the transverse longitudinal surface of the donated human teeth from the hospital.To observe the mineralization of the closed tooth body in simulated body fluids,through high power scanning electron microscope,EDS and other tests found that in the dental tube,healthy enamel area,coating the mineral water gel before and after the tooth difference is huge,mineralization results are obvious,and mineralization of the resulting sediments as hydroxyapatite,And the morphology is consistent with the pure in vitro simulation experiment,close to the human nature of hydroxyapatite morphology,can successfully closed the small tube,improve the enamel surface state,and thus prevent the healthy teeth in the enamel damage in the case of further external fungal infection to the dentin region caused by tooth sensitivity or pain.The experimental results show that the hydrogel material has high clinical application potential in oral cavity defect,not only the material itself is easy to be coated,but also the sealing protection effect of the tooth is remarkable.