Enzymatically hardened calcium phosphate biocement with phytic acid addition.

Novel enzymatically hardened tetracalcium phosphate/monetite cements were prepared applying phytic acid/phytase (PHYT/F3P) mixture as hardening liquid after dissolving in acetic acid solution (CX cement). Properties of the cements were compared with classic cement hardened with 2% NaH2PO4 (C cement) and cement hardened with acetic acid solution (CAC cement) only. In the microstructure of CX cement, columnar growth of hydroxyapatite particles was found in the form of walls around hydroxyapatite agglomerates originated from tetracalcium phosphate which were mutually separated by a material depleted low density zone. Wet compressive strengths (CS) of all cements were practically identical contrary to about 30% higher dry CS's of CX and CAC cements due to specific microstructure. It was verified noncytotoxic character of CX cement extracts and positive effect of CX cement on ALP activity and cell behavior during cultivation. The final Ca/P molar ratio and setting time of cement were effectively controlled by the amount of phytic acid and the change in PHYT/F3P mass ratio, or reaction time in hardening liquid, respectively.