| Reseach Background: people in the production, life, movement, and so oft-enencountered in the process of accidental injury, thus making different kinds, different degreeof fractures. At the same time, the damage of bo-ne tissue and bone defect caused by variousdiseases become more and more serious with the coming of aging society. This kind offracture, bo-ne defect caused by disease, accidents is the clinical common diseases, w-ith thedevelopment of biomedicine, promoting bone tissue repair of bio-medical materials forextensive clinical need to obtain the development o-pportunity. Currently in clinicalbiomedical material mainly includebiomed-ical metal materials, biomedical organicmaterials (mainly refers to the organic polymer materials), biomedical inorganicnon-metallic materials (mai-nly refers to the biological ceramics, biological glass and carbonmaterials) and biomedical composite materials, etc. Biomedical metal materials in manybiological materials, due to the high strength, toughness, fatigue re-sistance, good processingperformance, are more applicable to restore and replace human bone. But ordinarybiomedical metallic materials in huma-n environment ionization, electrolytic release harmfulion, or metal materi-al and debris caused by bone rubbing will cause allergy, cancer andsid-e effects, even implant failures because of body fluids of metal material corrosionfunction.Therefore, the research and development of new metal base creature implantmaterials is necessary and is very urgent.the development of Biomedical material requireshuman beings seek a kind of bone tissue repair materials which is similar to humanskeleton and biological properties, is able to give full play to the fixed function after theimplant, and can promote tissue repair, accelerate the healing of the body and other surgicalmaterials. And when the human body completely healed, the implanted biological materialsto be automatic degradation, be absorbed by human body, not on the body to produce sideeffects, and has good easy process characteristics. Based on the above requirements, theadvantages of magnesium and the magnesium alloy highlighted increasingly come out, andthe other metal can’t replace it that has very big development space in the new biologicalmaterial field. Compared with the traditional metal materials, magnesium alloy has obviousadvantages. First of all,metal magnesium resources are abundant, easily obtained, low price.Secondly metal magnesium density is low, only1.74g/cm3, and the same to the densityof the human (1.75g/cm3). Magnesium strength and fatigue resistance are better than lightbiological materials apatite,and magnesium and other commonly used metal matrix implant materials (such as titanium alloy, stainless steel) compared with the elastic modulus closer tonatural bone tissue, using magnesium alloys as internal fixation materials on fracture repairprocess avoid stress shelter effect of the implant materials on large drgree.At the same time,magnesium or indispensable element of human body, magnesium ions trace releasebeneficially to human body and harmless, and it can promote the metabolism of the calciumand vitamin, human bone growth, meanwhile adjust the muscle and neural activity,and serveas a catalyst in the role in the body. Although magnesium and magnesium alloy has manyadvantages, magnesium widely used in clinical still need a lot of experiments, because ofits shortcomings will also is very obvious. And compared with titanium alloy, stainless steel,metal matrix material, magnesium materials fragility is bigger, plasticity, deformabilityare worse in t fluid environment of he human body is easy corrosion, degradation,and limitsthe clinical application of large scope. Researchers work hard through the various methods toenhance the magnesium alloy toughness, corrosion resistance, organization, mechanicalproperties and biocompatibility, developing the Mg-Zn, Mg-Ca, Mg-Zn, Mn departmentalloy in recent years, in the field of biomedical materials excellent performance, but eachhas some defects, and new development which meets the requirements of the human bodyimplanted magnesium alloy is imperative. This article introduced the Mg-Zn-Ca-Y alloyadoping a bone of Ca element, the role of beneficial Zn elements, and increase the corrosionresistance of the magnesium alloy of rare earth elements as alloying elements Y, through theappropriate ratio, using traditional melting forging technology to make new Mg-Zn-Ca-Yalloy. This experiment through the Mg-Zn-Ca-Y alloy proceeds cell toxicity tests, in theorganization of the alloy cells compatibility test toxicity, and to make the preliminaryevaluation organization compatibility, a visit to the implantation as biomedical materials inthe possibility of clinical application, to provide the scientific basis for the development ofa new generation of biomedical materials.Objective:This study is to evaluate the vitro and in vivo biocompatibility ofMg-Zn-Ca-Y alloys and provide a scientific basis for improving the alloy melting processand mading suitable for clinical application of a new calcium, magnesium, zinc, yttriumalloy.Methods:The Mg-Zn-Ca-Y alloy extracts and mouse fibroblasts (L929cells) weremixed together and cultured,we use inverted phase contrast microscope to observe cellmorphology, quantify cytotoxic and calculate the relative value-added rate(RGR),then wewould got Preliminary evaluation of the cytotoxicity of the magnesium alloy. Mg-Zn-Ca -Y alloy specimens were implanted in the sacral spine muscle of the Japanese white rabbitsto observe rabbits in general and the implantation point organization.One month later,we useoptical microscope to observe Magnesium alloy surrounding muscle tissue inflammatorychanges in the situation.three months later,six months later,we use scanning electronmicroscopy to observe the thickness of fiber membrane on Magnesium alloy,then we gotpreliminary evaluation of the magnesium alloy in vivo biocompatibility.Result: The Mg-Zn-Ca-Y alloy extracts and mouse fibroblasts (L929cells) weremixed together and cultured24hours,48hours,72hours,the RGR was more than%in allgroups and cytotoxieity scoring is in grade1. There were signifieant differe-nce betweenexperimental group， positive group and negative group(P<0.05) whilethere were nosignificant difference between negative group and extraeting liquids g-roup(P>0.05).AfterMg-Zn-Ca-Y alloy specimens were implanted in the sacral spine muscle of the Japanesewhite rabbits,there were no swelling and secretions on i-ncision.One month later,I found thatthere were no obvious degradation, no bubbles,but the surrounding tissue formed a fibrousmembrane surround the specimen and Magnesium alloy surface was oxidized black.Thethickness of fiber membrane was0.4millimeter.Three months later,the specimen surface wasstill smooth and oxidized black,there were no excessive gas production and degradation. Sixmonths later, the specimen surface was also oxidized black,no gas production,but thespecimen began to degrade. The results of scanning electron microscopy showed thatdifferent part-s of specimen were all in line with the requirements of less than30micron.Conclusion:The Mg-Zn-Ca-Y alloys showed no cytotoxicity.It have goodbiocompati-bility, which were suitable as a biomedieal material. |
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