バイオミメティック法による有機高分子表面へのアパタイト層のコーティング

Abstract

A dense and uniform layer in any thickness of highly biologically active bone-like apatite layer can be formed on the surfaces of any kind. of solid materials in any shape at the normal temperature and pressure by the following biomimetic method: First, a substrate is placed on or in CaO-Si02 based glass particles soaked in a simulated body fluid(SBF) with ion concentrations nearly equal to those of human blood plasma in order to form a lot of apatite nuclei on the surface of the substrate. Then, the substrate is soaked in another solution highly supersaturated with respect to the apatite e.g. that with ion concentrations 1.5 times those of SBF (1.5SBF) in order to make the apatite nuclei grow on the substrate in situ. Thus obtained apatite-organic polymer composites are expected to be useful as the bone-repairing materials as well as soft tissue-repairing materials. In these applications, adhesive strength of the apatite to the substrate is an important property. In the present study, effect of NaOH treatment of the substrate before the nucleation treatment on the adhesive strength of the apatite layer formed by the biomimetic method was investigated. Polyethyleneterephthalate (PET), polymethylmethacrylate(PMMA) and polyamide 6(Nylon 6) increased the adhesive strengths from 3.5 to 8.6, from 1.1 to 3.4 and from 0.6 to 5.3 MPa, respectively, by the 5N-NaOH pre-treatment for 10 min, whereas polyethylene(PE) polyethersulfone(PESF) and polytetrafluoroethylene(PTFE) did not increase it. The increase in the adhesive strength for the former three kinds of polymers was attributed to the formation of the carboxyl group which has high polarity and forms strong bond to the apatite by hydrolysis of ester group in PET and PMMA and amido group in Nylon 6 with the NaOH treatment.