Environmental Behavior Of Magnesium And Titanium Metals Under Typical Simulated Body Fluids

Evaluation of the properties is an important part of biomaterials study,whether the materials can use clinical depend on it.However,with the development of materials and in vitro simulation tests of biodegradable materials,it is found that the results often are quite different from those in vivo.Therefore,in view of two common biomaterials,magnesium and titanium,the in vitro evaluation methods and biocompatibility of biomaterials were investigated by changing in vitro environmental factors and the surface state of materials in this paper.（1）with magnesium metal as the research object,examines the difference of evaluation in vitro and in vivo evaluation of typical and simulated body fluid environment,analyzes the influence of local micro environment,explore the evaluation of organic and inorganic SBF differences,as well as by surface laser modification to improve biological activity.The results show that the simulated corrosion rate of magnesium metal implants is much higher than that of animal test.In the medium of PBS and SBF,in the medium of PBS and SBF,the corrosion rate of pure magnesium is very fast,and a serious pitting phenomenon occurs in the medium containing chloride ion.In the presence of calcium ions,the corrosion rate increases because of the poor densification of the corrosion products produced on the substrate surface.When the local solution contact between the sample surface and the solution interface is not enough,the ions cannot be replenish to the interface in time when the reaction is consumed,just like in the intramedullary environment,the corrosion rate of the sample will be greatly reduced.After adding 0.05g/L bovine serum albumin,protein solution through the influence of inorganic ions to the surface mass transfer,which will further affect the formation of corrosion product film,the film had poor density change is good film density,thereby preventing further corrosion.And hierarchical structures with microscale rings and cauliflower-like clusters as well as nanoscale ripples on the Mg surface were fabricated by laser diffraction and interference structuring,which provides a suitable environment for cell growth in cell growth and protein adsorption test,and is conducive to improve the surface bioactivity.（2）Taking titanium as the object of study,the influence of gravity and dynamic flow on the formation of bone like phosphor layer on titanium surface was explored,and the growth of bone like apatite was promoted through surface roughening.The results show that vertical gravity factors are more influential than horizontal gravity free factors,and bone like apatite on titanium surface accelerates deposition,and the growth of bone like apatite is uneven.In the static environment,the formation of bone like apatite on the titanium surface was delayed under the dynamic environment.This is due to the fact that under the dynamic environment,Ca²⁺,HPO₄^2-and PO₄^3-ions have been taken away under the condition of not nucleating,resulting in late formation of apatite in dynamic environment.The rate of formation of bone like apatite is more clear and dense than that of 120 rpm,which is equivalent to the dynamic state of normal physiological flow rate in the body when 360 rpm is equivalent to the dynamic state in the body which is larger than the normal physiological flow velocity.Sandblasting treatment increased the surface roughness of titanium,reduced the growth and cracking of calcium phosphorus layer,and promoted the growth of surface bone apatite,and promoted the formation of bone like apatite.