Production and characterisation of a collagen-calcium phosphate composite for use as a bone substitute

A composite for use as a bone substitute has been produced by the precipitation of calcium phosphate onto a collagen matrix. A collagen sheet is used as a membrane separating reservoirs of calcium and phosphate ions. The ions diffuse through the membrane and calcium phosphate precipitation occurs on and within the collagen matrix. Composites containing octacalcium phosphate or hydroxyapatite have been produced by varying the precipitation pH. If the correct balance of phosphate and calcium ion concentrations is achieved, precipitation occurs through the entire cross-section of the collagen sheet, giving a composite microstructure analogous to bone. The composite stiffness increases with increasing mineral content, reaching 2.8 GPa with 39 wt % mineral, when measured dry.