The in situ synthesis of biphasic calcium phosphate scaffolds with controllable compositions, structures, and adjustable properties

In this study, biphasic calcium phosphate (BCP) porous scaffolds with controllable phase compositions, controllable macropore percentages, and this adjustable properties were in situ prepared by sintering a series of composites consisted of calcium phosphate cement (CPC) and porous resin negative mold made from rapid prototyping (RP) technique. The CPC pastes were formed by mixing a power mixture of tetracalcium phosphate and anhydrous dicalcium phosphate with liquid phase of diluted phosphate acid solution. Results show that the phase composition was easily adjustable by controlling both weight ration of the powder mixture to the liquid phase (P/L) and concentration of the liquid phase. The macropore structure of the BCP scaffold can be regulated by using different RP negative molds. Through in vitro compressive strength (CS) and immersion tests, it was demonstrated that both macropore percentage and phase composition played importatn role in the CS also the dissolving rates of the scaffolds. As the macropore percentages of the scaffold increased, its CS decreased but the dissolving rate increased; also, as the weight ratio of hydroxypatitet to tricalcium (HA/TCP) in the scaffold increased, the CS first increased. The CS values of the BCP scaffolds with a HA/TCP weight ration of 59:41 were 5.84 +/- 1.16 MPa for a total porosity of similar to 67.67% containing a macropore percentage of 30%, and 3.34 +/- 0.79 MPa for a total porosity of similar to 70.90% containing a macropore percentage 50%, respectively, comparable to the corresponding levels of human cancellous bone (2-12 MPa). (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 88A: 34-42, 2009