Minocycline Modification Of Gelatin-fluorapatite Nano-composite For Bone Repairment

Objective To bionic synthesise a new antibacterial composite materials for bone repairment and establish the bionic design platform of the antibacterial biological functional human hard tussue repair materials. Based on the previous studies, this paper discusses the modification of minocycline to the structure of the gelatin-fluoriapatite and evaluate its biological effects.Methods Base on the biological mineralization theories of the inorganic ctystal growth controlled by organic matrix, a new material was synthdsised by using the bionic chemical materials synthesis technology. A certain amount of acidic solution of hydroxyapatite(wt%,1.67%,5g HA dissolved in the1M HCl300ml) and sodium fluoride(0.4183g NaF was added into the solution above) solution was added into gelatin solution(wt%,0.67%,2g Gel dissolved in the1M NaOH300ml) drop by drop. Thirty minutes later, different amounts of minocycline (0mg:M-000;50mg:M-050;100mg:M-100;200mg:M-200;300mg:M-300) solution was added into the reaction system respectively, and kept the system at about40℃and pH8for1-2h, then aged overnight at pH7-8to obtain the composite of gelatin-flourapatite-minocycline nano-hydrocolloid. A part of the nano-hydrocolloid was dried to obtain "Gel-FA-M" particles and obtain the gelatin-flourapatite-minocycline composites."Gel-FA-M" composite was characterized by FTIR, XRD, SEM, TEM and thermal analysis. The BMSCs was cultured with the materials for assessing its cell biocompatibility. The materials was implanted in to the dog root bifurcate lesions to evaluate the effect of periodontal bone repair. Results The SEM, TEM, FTIR XRF and the XRD spectra showed the formation of low-crystallinity FA, and the effect of minocysline incorporation to the growth of flourapatite crystal. TG and DSC demonstrated that the material was composed of organic and inorganic composition, and the rate of the inorganic component was approximate87%. The corporation of the minocycline had effcct to the fluorapatite crystal growth, with the amount of the minocycline increasing, the rate of the length(c axis) to the width (a axis) increased, but when the rate increased a critical point it induced significantly. The result showed that the superstandard amount of minocycline inhibited the growth of the crystal length. The minocycline showed the ability of relesse in vitro, and it can maintain the effective antimicrobial effect in two weeks. The composite materials had good cell compatibility, promoting the proliferation and osteoblast differentiation of BMSCs. Dog root bifurcate alveolar bone defect model showed that complex materials had good bone repair function, and the content of minocycline affected the bone repair efficiency.Conclusions Biomimetic synthesis "Gel-FA-M" composite was combination of organic and inorganic components, fluorapatite crystal was evenly distributed among the gelatin; The amount of minocycline added affected fluorapatite crystal size as well as growth dirction; The minocycline modified composite material can slowly release antibacterial drugs and maintain effective antimicrobial concentration in two weeks; The composite material showed a good compatibility to BMSCs, but the composite material containing a high levels of minocycline showed mild inhibitory to the BMSCs; The repair of the dog root bifurcatf alveolar bone defect displayed that the biomimetic synthesis had good bone repair effect and it was a quite promising antibacterial bone repair and bone regeneration materials.