Preparation And Performance Of Gelatin/glycine Modified Nano-hydroxyapatite Enamel Repair Membrane

Dental caries are one of the most common oral diseases in humans,And usually it is irreversible and permanent.For early caries,remineralization is generally used for treatment.At present,fluoride is the most widely used remineralization material,but the use of fluoride is limited due to the toxicity and the dental fluorosis.Based on the above content,In this paper,gelatin(GE)and glycine modified nano-hydroxyapatite(HAP-Gly)were used as raw materials to prepare a enamel remineralized film with porous structure by electrospinning method to induce inorganic matter in demineralized enamel.Then characterize the effect of enamel remineralization.The main research contents and results include:(1)Using gelatin(GE)as raw material,GE fiber was prepared by electrospinning technology,and the optimal spinning parameters of GE were explored by orthogonal experiment.The GE electrospun fibers are crosslinked with1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDC)and glutaraldehyde(GA)respectively,A crosslinking method is preferred for use in the preparation of subsequent materials.The orthogonal experimental results show that when the concentration of GE solution is 24%,the positive pressure of spinning is 22KV,and the receiving distance is10cm,the spinning effect is the best.Comparing the two cross-linking methods,it can be seen that the mechanical properties of EDC cross-linking are better,the degree of cross-linking is higher,and there is no cytotoxicity,which is beneficial to subsequent applications.(2)Glycine-modified nano-hydroxyapatite(HAP-Gly)powder was prepared by co-titration using calcium hydroxide,phosphoric acid and glycine(Gly)as raw materials.The composition and structure of the powder were characterized by X-ray diffractometry(XRD)and transmission electron microscopy(TEM).The results show that the HAP-Gly powder prepared in this experiment has no other heterogeneous phase and has high purity.However,since Gly has a certain influence on the crystallization properties of HAP,the diffraction peak of the modified HAP is significantly broadened;HAP-Gly is a cluster-like rod structure with a length of about 50-130nm and a diameter of about 5-15nm;The cytotoxicity of HAP-Gly powder was confirmed to be non-cytotoxic.(3)GE/HAP-Gly composite fiber membranes were prepared by electrospinning using GE and HAP-Gly as raw materials,and their structures were observed by scanning electron microscopy(SEM)and inductively coupled plasma atomic emission spectrometry(ICP-AES).And mineralization performance is tested.The SEM results show that the HAP-Gly powder particles are agglomerated inside or on the surface of the GE fiber,which causes the surface of some fibers to protrude,which makes the surface roughness of the material increase,which is beneficial to promote protein adsorption and cell adhesion and proliferation.The results of ICP-AES test show that the GE/HAP-Gly composite membrane can continuously release calcium and phosphorus ions,which provides good conditions for remineralization of demineralized enamel.(4)The GE/HAP-Gly fiber membrane was attached to the surface of the demineralized enamel to study its effect on remineralization of the enamel surface.The enamel surface remineralization was investigated by microhardness test,scanning electron microscopy,X-ray diffraction,etc.The results showed that the microhardness value(HV)of the enamel surface was increased after remineralization with the fiber membrane.40.6kg/mm~2,the crack on the enamel surface of the demineralized tooth has been significantly reduced,and the apatite crystal lattice has recovered to a certain extent,which proves that the GE/HAP-Gly fiber membrane has a certain effect on the remineralization of enamel.