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A laminin-apatite composite layer with reduced surface roughness was successfully formed on a substrate of ethylene vinyl alcohol copolymer in a calcium phosphate solution supplemented with MgSO 4 as an inhibitor of apatite crystal growth. The obtained composite has potential as a material for percutaneous devices with improved resistance to bacterial infection.

Fibronectin (FN) and type I collagen (Col), which are kinds of extracelluar matrices, were coprecipitated with calcium phosphate to form a composite layer on a hydroxyapatite (HAP) ceramic using a supersaturated calcium phosphate solution (CP solution). The amounts of protein immobilized in the layers were determined to be 20.97±3.04 µg·cm-2 for FN, 5.26±0.19 µg·cm-2 for Col and 21.72±2.30 µg·cm-2 for simultaneously immobilized FN and Col. When osteoblastic MC3T3-E1 cells were cultured on the HAP ceramics with the composite layer containing FN and/or Col, calcified tissue was formed through the activity of the cells. The result showed that the composite layer accelerated the differentiation of MC3T3-E1 to bone-forming cells. It is assumed that osteoblastic cells in alveolar bone migrated and differentiated on the surface of the tooth roots when the artificial tooth roots were covered with the composite layer.

Fibronectin (FN)-apatite composite layers were formed on a hydroxyapatite (HAP) ceramic using supersaturated calcium phosphate (CP) solutions. The surface roughness of the composite layer could be controllable by changing the magnesium (Mg) concentration in the CP solution. The higher the Mg concentration, the smaller the apatite crystals in the layer were. The thickness of the layer formed in the CP solution containing 1.5 mM Mg decreased to 68% that formed in the Mg-free CP solution. The amount of FN immobilized in the layer was almost constant regardless of Mg concentration in the CP solution in the range from 0 to 1.5 mM. The results of the present study revealed that a thin FN-apatite composite layer with a smooth surface and a high protein content is formed in a CP solution at a Mg concentration of 1.5 mM.

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