| Objective:The paper studies the key technological conditions for the antibacterial modification of coral hydroxyapatite(Coral Hydroxyapatite,CHA)surface by using nanometer zinc oxide(nanometer zinc oxide,nmZnO)prepared by sol-gel method..According to the detection results of the synchronous thermal analyzer,the heat treatment conditions for preparing CHA/nmZnO composite materials are explored.The porous composite artificial bone material with good osteogenic activity and antibacterial property is prepared,and the degradation property of CHA/nmZnO composite material in vitro are also preliminarily studied.Methods:?Natural coral and diammonium hydrogen phosphate were used as raw materials to carry out a "hydrothermal reaction" in a special high-temperature high-pressure reaction kettle,with the reaction temperature:180? and reaction time:12 hours.After the reaction,the yellowish-white CHA particles were obtained by ultrasonic and water bath cleaning.The surface morphology and phase composition of the composite were analyzed by Scanning Electron Microscope(Scanning Electron Microscope,SEM)and X-Ray Diffractomer(X-Ray Diffractomer,XRD).?Used zinc nitrate as raw material and polyethylene glycol-6000(Polyethylene glycol 6000,PEG-6000)as dispersant to carry out antibacterial modification for the surface of CHA particles by sol-gel method;setting the reaction temperature at 70?,adjusting the PH value of the solution to be within the range of 6.2-6.4,the white porous antibacterial CHA/nmZnO composite material was obtained after ultrasonic cleaning,magnetic rotary stirring,thorough drying and heat treatment.Through XRD and SEM detection,the chemical element composition and surface morphology of the material were studied,and the effects of different raw material ratios and heat treatment conditions on the particle size and distribution of nano-particles on the surface of CHA/nmZnO were investigated.Finally,ideal antibacterial modification process conditions were determined and porous antibacterial CHA/nmZnO composite materials were prepared.Degradation experiments in vitro were conducted in accordance with ISO 10993-14:2001 standard,and Tris-Hcl degradation solution was prepared according to the standard recommended method.The experiment was conducted for 7 days.The experimental groups were divided into four groups:natural coral group,CHA particle group,CHA/nmZnO particle group and Bio-oss bone meal group.Three parallel experiments were set up in each group.The materials of each group were filtered and weighed on 1st day,3rd day and 7th day to respectively calculate the weight loss and degradation rate of each group,and the degradation performance of the composite was preliminarily explored based on the degradation rate of the materials.SEM was used to detect and analyze the surface morphology of the material before and after degradation;XRD was used to detect the change of chemical composition of samples before and after degradation..Results:? After the natural corals were cleaned&disinfected,ground&sieved and subjected to hydrothermal reaction,the yellowish-white porous CHA particles were obtained.XRD results show that the sample has hydroxyapatite characteristic peak,and the main characteristic peak is calcium carbonate characteristic peak.The results of SEM examination show that scaly substances are formed on the surface of the material,and the original pore structure of coral is not damaged.? In the process of antibacterial modification of CHA surface by sol-gel method,under the condition of the mass ratio of CHA,zinc nitrate and PEG-6000 is 48:4:5,the results of SEM detection show that round nanoparticles with uniform distribution are fused on the surface of the composite material,the particle sizes are all controlled below 70nm,no obvious agglomeration phenomenon is found,the CHA structure is not damaged,and the distribution of nanoparticles is also found in vugs,pores and other places.According to the results of Energy Dispersive X-ray Spectroscopy(Energy Dispersive X-Ray Spectroscopy,EDX),the round nanoparticles are nmZnO;XRD patterns show that the composite material has zinc oxide characteristic peak.According to degradation experiments in vitro,in four groups of materials,namely natural coral,CHA,CHA/nmZnO and Bio-oss,there are all degradation phenomena in different degrees after soaking in Tris-Hcl buffer solution for 7 days,with the degradation rate of 9.71%,7.84%,19.27%and 3.22%respectively.The porous CHA/nmZnO composite material has the best degradation performance among the four groups of samples.SEM results indicate that the pores and broken end edges of CHA/nmZnO group are the main degradation sites;the hydroxyapatite layer on the surface is partially disintegrated and fell off,exposing the internal calcium carbonate structure in the shape of bean dregs.The pore size at the pore-like structure is increased,and the overall appearance is pit-like.The main degradation reaction site of CHA group is the same as that of CHA/nmZnO group.The hydroxyapatite layer on the surface falls off slightly,and the inside is exposed in needle shape;the structural integrity of the pore wall is destroyed and the pore diameter is slightly increased.According to XRD test results,the chemical element composition of CHA particles has not changed before and after degradation;the characteristic peaks of ZnO and Ca(OH)2 in the degraded CHA/nmZnO antibacterial artificial bone composite disappear,which indicates that the nmZnO particles adhered to the sample surface and a small amount of CaO components converted in the heat treatment process are degraded in Tris-Hcl buffer solution,and the residual material after degradation is a mixed materials with calcium carbonate as the main characteristic peak and hydroxyapatite characteristic peak.Conclusions:CHA can be prepared by hydrothermal reaction principle,and the materal is mainly composed of calcium carbonate and hydroxyapatite.The sol-gel method can be used for antibacterial modification on CHA surface.Under the ideal modification conditions of,PH value within 6.2-6.4,the reaction temperature of 70?,the mass ratio of CHA,zinc nitrate and PEG-6000 in 48:4:5,The nano ZnO particles on the surface of the CHA/nmZnO composite are evenly distributed and the particle size is less than 70nm.The porous CHA/nmZnO artificial bone composite material can be degraded in Tris-Hcl buffer solution. |
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