The Functionalization of Calcium Phosphate Materials of Protein-based Biologically Active Molecules

Recent approaches to the calcium phosphate (CaP) materials functionalization with drugs and biomolecules have been actively developed for bone defect reconstruction. However, the current techniques are low efficient in context of drug incorporation and non-controlled release from the materials. Eventually, continuous therapeutic effect in bone defect area couldn’t be achieved. The aim of this work was to develop an effective method for biologically active molecules incorporation onto the surface of CаP materials, and to study the dynamics of its release. Octacalcium phosphate (OCP), β-tricalcium phosphate (β-TCP) and β-tricalcium phosphate with biomimetic calcium phosphate layer (β-TCPmod.) were used as ceramic bioactive carriers. Bovine serum albumin (BSA) was used as a model compounds. BSA incorporation on the ceramics surface was performed by biomimetic co-precipitation from several buffer solutions containing the incorporated compound. The efficiency of biomolecules incorporation was evaluated by measuring BSA concentrations in solutions before and after materials incubation. The release of the incorporated molecules from the materials was investigated for 6 days. The structure and composition of the obtained materials were studied by application of XRD, FTIR, SEM, BET methods. It was shown that the OCP specific surface (surface area, (SBET)) was almost in 12 times higher than SBET of β-TCP. By using biomimetic approach the increase of β-TCP surface area in 1.6 times was achieved; this enhanced protein incorporation more than 3 times. The BSA biomimetic co-precipitation together with CaP on the OCP surface proved to be more effective than its adsorption from salt free solutions. The study of BSA release revealed that only 45% of loaded albumin released during 6 days of observation. Therefore, the effective method of CaP functionalization was developed. Based on biomolecules incorporation by biomimetic co-precipitation from CaP solutions, it provided a low rate of its release.