The Osteo-inductivity Of Zinc Doped Calcium Phosphate Coating On "Tixos^TM"

Objective:To construct nano scaled Calcium phosphate coatings doped with differentconcentration of Zinc on novel implant system--“Tixos”; To evaluate thesebio-coatings’ effect on MG-63cells’ early adhesion, proliferation, differentiation andmatrix mineralization in cell model and thus screen out the most effective doped Zincconcentration.Methods:Calcium phosphate coatings doped with different concentrations of Zinc wereconstructed on “Tixos” implants by Chronopotentiometry-electrochemical depositionprocess. Single cells group served as blank control, simply “Tixos” worked asnegative control and Zinc doped Calcium phosphate coatings with differentZn/(Zn+Ca) mole ratios (0,10%,20%and30%) were used as experimental groups.After materials and cells co-culture, at1hour cell adhesion amounts were tested byDAPI staining, at1,4and7day CCK-8was used to evaluate the influence ofbio-materials on cells’ proliferation, at7day we accessed intra-cellular AKP activityin quantity, at14day total cellular protein concentrations were evaluated by BCAmethod, bone formation related genes--RUNX2, OCN and Osterix’ mRNA expressionlevels were tested by Real-Time PCR and meanwhile the expression of those proteinsworking in the process of matrix mineralization were tested by Westernblot.Results:1.Zinc doped Calcium phosphate coating on “Tixos” can promote MG-63cells’early adhesion at1hour after co-culture. Among these bio-coatings,20%Zn-HA and30%Zn-HA groups’ positive effect on cells’ adhesion was more obvious; 2.Zinc doped Calcium phosphate coating on “Tixos” can promote MG-63cells’early proliferation at4,7day after co-culture, while the most substantial promotionwas from20%Zn-HA group at7day;3.Compared with the blank and negative control groups, experimental groupscould upregulate AKP activity in MG-63cells among which20%doped Zinc couldexert the most obvious promotive effect;4.Compared with control groups,20%Zn-HA group could dramatically promotetotal protein expression;5.20%Zn-HA group could also up-regulate RUNX2、OCN、Osterix mRNAexpression level at9,14day after co-culture;6. During early and late stage of mineralization,20%Zn-HA positively regulatedthe expression of osteogenesis-related proteins--Collagen I and BSP.Conclusion:1.Zinc doped Calcium phosphate coatings on “Tixos” can enhanceosteoblast-like cells’ early adhesion, proliferation, early and late stage differentiationand matrix mineralization;2.Among different concentrations of Zinc doped in HA coatings,20%mole ratiois the most effective in terms of promoting bone formation;3.The bioactivity of Zinc ion is concentration-dependent,30%mole ratio Zincdoped in HA coating maybe is cytotoxic;4.Osteoblast-like cells prefer to attach on nanoscale rough surface instead ofsharp edged surface.