RF magnetron-sputtered coatings deposited from biphasic calcium phosphate targets for biomedical implant applications

Bioactive calcium phosphate coatings were deposited by radio-frequency magnetron sputtering from biphasic targets of hydroxyapatite and tricalcium phosphate,sintered at different mass%ratios.According to Raman scattering and X-ray diffraction data,the deposited hydroxyapatite coatings have a disordered structure.High-temperature treatment of the coatings in air leads to a transformation of the quasi-amorphous structure into a crystalline one.A correlation has been observed between the increase in the Ca content in the coatings and a subsequent decrease in Ca in the biphasic targets after a series of deposition processes.It was proposed that the addition of tricalcium phosphate to the targets would led to a finer coating's surface topography with the average size of 78 nm for the structural elements.

Biocompatibility of biphasic α,β-tricalcium phosphate ceramics in vitro

The biocompatibility of biphasicα,β-tricalcium phosphate ceramics,obtained by annealing a compact preform based onβ-tricalcium phosphate powder,was studied in vitro.It was found that within 10–30 days the adhesion of primary dental pulp stem cells located on the surface of biphasicα,β-tricalcium phosphate ceramics is suppressed.Decrease of the cell number on the surface of biphasicα,β-tricalcium phosphate ceramics,most likely,can be associated with both the pH level(acidic)as a result of hydrolysis of the more soluble phase ofα-tricalcium phosphate and with the nature of surface that changes as a result of the formation and growth of hydroxyapatite crystals.

Colloidal forming of macroporous calcium pyrophosphate bioceramics in 3D-printed molds

A technique for colloidal forming of Ca2P2O7 macroporous bioceramics,based on low-pressure injection molding(LPIM)of a glycerol-water slip containing Ca2P2O7 and Ca(Н2PO4)2 into a plastic mold fabricated via FDM 3Dprinting,was proposed.Chemical reaction between the solid phases of the water containing slip-Ca2P2O7 and Ca(Н2PO4)2,resulting in brushite(CaHPO4·2H2O)formation,led to consolidation of the casting and preserved its complex architecture in the course of mold burning-out.Macroporous ceramics of Kelvin structure(70%macropores with the sizes from 2 up to 4 mm),based on a pre-defined composition with 10 wt%Ca(PO3)2 and sintered in liquid-phase regime,demonstrated a compressive strength of 1.4±0.1 MPa at a density of 22±2%.In vitro tests on bioactivity in SBF solution,as well as on resorption of the ceramics in model solution of citric acid,were carried out.

Structural modification of titanium surface by octacalcium phosphate via Pulsed Laser Deposition and chemical treatment

In the present study, the Pulsed Laser Deposition (PLD) technique was applied to coat titanium for orthopaedicand dental implant applications. Calcium carbonate (CC) was used as starting coating material.The deposited CC films were transformed into octacalcium phosphate (OCP) by chemical treatments. Theresults of X-ray diffraction (XRD), Raman, Fourier Transform Infrared Spectroscopy (FTIR) and scanningelectron microscopy (SEM) studies revealed that the final OCP thin films are formed on the titaniumsurface. Human myofibroblasts from peripheral vessels and the primary bone marrow mesenchymalstromal cells (BMMSs) were cultured on the investigated materials. It was shown that all the investigatedsamples had no short-term toxic effects on cells. The rate of division of myofibroblast cells growing onthe surface and saturated BMMSs concentration for the OCP coating were about two times faster than ofcells growing on the CC films.