Synthesis Of Novel Antibacterial Hydroxyapatite Nanofiber And Its Application In Dental Resin

Objectives:The antibacterial hydroxyapatite nanofiber,as a modified filler,was synthesized and added to the resin matrix to prepare a new dental resin with improved antibacterial activity and remineralization capability,with the view to proposing a strategy for functional design of dental resin.Methods:(1)Synthesis of novel antibacterial hydroxyapatite nanofiber.The silanized hydroxyapatite nanofibers(s-HAFs)were prepared by hydrothermal method.According to the mass ratio of s-HAFs:EM equal to 1:0.5 and 1:0.25,two types of new antibacterial hydroxyapatite nanofibers were prepared,denoted as s-HAFs@EM-50 and s-HAFs@EM-25,respectively.Scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),Simultaneous thermal analyzer(STA),Zeta potential and spectrophotometer were employed to characterize the micro-morphology,phase structure,chemical composition and drug loading capacity(LC)of the new antibacterial hydroxyapatite nanofiber.The antibacterial activity was evaluated by colony counting method and agar plate diffusion method.(2)Preparation of novel antibacterial and remineralized dental resin.Bis-GMA(Bisphenol A glycerolate dimethacrylate)and TEGDMA(Triethylene glycol dimethacrylate)were mixed evenly in equal proportions according to mass ratio to produce organic resin matrix.CQ(Camphorquinone)and 4E(4-dimethylaminobenzoate)with mass fraction of 0.2wt%and 0.8wt%,respectively,were added into the matrix.Then,the novel antibacterial hydroxyapatite nanofibers were incorporated at different mass fractions(0wt%,5wt%,10wt%,15wt%,and 20wt%)and mixed in the dark room.The novel antibacterial and remineralized dental resin was prepared.The mechanical property,antibacterial activity,remineralization capability and biosafety of the dental resin were evaluated.Results have been analyzed statistically(P=0.05).Results:(1)The novel antibacterial hydroxyapatite nanofiber was successfully synthesized.It was white solid cotton wool with fibrous morphology.The diameter of single fiber was about 100nm and the length is tens of microns,and there were EM nanoparticles attached on the fiber surface.According to FT-IR characterization,the silane coupling agent KH-570 was grafted onto nanohydroxyapatite fibers(HAFs),the graft rate was(6.12±0.28)%evaluated by TG analysis.Zeta potential results showed that the absolute values of s-HAFs@EM-25 and s-HAFs@EM-50 decreased,which were(-24.60±8.35)mV and(-28.13±0.38)mV,respectively,less than that of s-HAFs(-33.03±2.02)mV.The LC of s-HAFs@EM-25 and s-HAFs@EM-50 were(13.03±0.55)%and(34.07±1.52)%,respectively,and the antibacterial rates were 98.63%and 100%.Antibacterial activity was good.(2)The novel antibacterial and remineralized dental resin was prepared successfully.The bending strength and elastic modulus of the modified resin with 15wt%s-HAFs@EM-50 was(118.67±15.71)MPa and(2.02±0.3)GPa,respectively.Compared with the unmodified resin,the mechanical properties were significantly improved(P<0.05).The microstructure of the modified resin fracture is rough,and fiber bridging,nailing and pulling out could be observed.Resin contained with 15wt%novel antibacterial hydroxyapatite nanofibers,the antibacterial rate was more than 85%.Compared with the control resin,the antibacterial activity increased significantly(P<0.05).At the same time,the cytotoxicity test grade was 1,indicating no obvious cytotoxicity.The resin containing 15wt%s-HAFs@EM-50 was exposed to simulated body fluid(SBF)for 21 days,SEM showed that apatite mineralized layer was formed on the surface of the resin.Conclusions:Under this experimental condition,at the mass fraction of 15%,the mechanical property of the resin was improved,and the resin was endowed with antibacterial activity and remineralization capability,it also had good biosafety.This study provides a research guidance for the preparation of multi-functional dental resin materials.