Preparation and characterization of alpha-tricalcium phosphate cements incorporated with polyamino acids

Abstract

Polymeric calcium phosphate cements (PCPCs) derived from biodegradable polyamino acids, such as polyaspartic acid (PAA) and poly-gamma-glutamic acid (gamma-PGA), were prepared in an attempt to improve their cohesion strength and injectability. The characteristics of the calcium phosphate cements (CPCs), such as dynamic viscosity, paste injectability, initial setting time, compressive strength and cell compatibility, were assessed. The dynamic viscosity increased significantly with gamma-PGA incorporation but decreased with PAA incorporation. The injectability increased with the concentration of polyamino acids and that of the CPCs mixed with gamma-PGA reached 94%. The initial setting time decreased with the gamma-PGA concentration in the cement liquid and reached approximately 10-15 min when the gamma-PGA concentration was 1-2 wt%. The compressive strength (CS) of CPCs after 1 week-incubation decreased with the incorporation of PAA and gamma-PGA. gamma-PGA incorporation deteriorated the CS more than PAA incorporation because the dissolution of alpha-tricalcium phosphate (alpha-TCP) was retarded. Saos-2 cells grown on CPCs with polyamino acids spread more than those grown on the CPC without them.