Bioactivity of PEEK GRF30 and Ti6Al4V SLM in Simulated Body Fluid and Hank’s Balanced Salt Solution

In recent years, scientists have defined two main paths for orthopedic implant fabrication: searching for new materials with properties closest to natural bone in order to reduce the stress-shielding effect or creating individually adapted geometry of the implant with the use and Rapid Prototyping methods. Therefore, materials such as PEEK GRF30 and Ti6Al4V selective laser melting (SLM) are of interest. They are defined as materials suitable for implants, however, the knowledge of their bioactivity, a feature which is one of the most desirable properties of biomaterials, is still insufficient. Using Simulated Body Fluid and Hank’s Balanced Salt Solution, the bioactivity of PEEK GRF30 and Ti6Al4V SLM was assessed, as well as commercial Ti6Al4V as a reference material. Ten cylindrical samples of each material were prepared and immersed in solutions per period from 2 to 28 days at 37 °C. Optical analysis of the changes on the examined surfaces suggested that right after 2-day crystals with different morphologies were formed on each material. Further analysis of the chemical composition of the altered surfaces confirmed the formation of a calcium phosphate layer on them, however, the Ca/P ratio was slightly different from 1.67. On the basis of the obtained results, it can be concluded that both PEEK GRF30 and Ti6Al4V SLM are characterized by appropriate—comparable to Ti6Al4V—bioactivity.

Features of solubility and cytocompatibility in vitro of bone cements based on calcium sulfate containing phosphate ions

Cement materials have based on calcium sulfate were obtained, which have introduced up to 20 mol. % of phosphate groups to improve their cytocompatibility and solubility. It was found that during exposure of cement materials based on calcium sulfate, containing of 0, 5, 10 and 20 mol. % phosphate - groups, in model solutions SBF (Kokubo solution, simulating the composition of human blood plasma) and DPBS (Dulbecco's phosphate-buffered saline) in dynamics up to 28 days of were formation of a calcium-phosphate layer on the surface of the samples. At the same time, in SBF solution, the process of recrystallization of sulfate and phosphate phases occurs more pronounced than in DPBS solution. In vitro studies on the cell culture of the human osteosarcoma line MG-63, cement samples showed cytocompatibility with the presence of moderate surface matrix properties

Adaptable metamaterials based on biodegradable composites for bone tissue regeneration

The influence of lattice and shell type architecture on the mechanical properties of biodegradable polymer scaffolds designed to create structures for bone tissue engineering is investigated. Varying the topology of nodal connections allows you to control the relative rigidity of the metamaterial in the range from 0.004 to 0.123. The possibility of creating permeable scaffolds using thermally extruded 3D printing based on polymers of different elasticities - polylactide and polyurethane is shown. The use of “unit cells” of various types makes it possible to fabricate structures such as shells based on polylactide with a compressive strength of 1.5 to 19.7 MPa. Shells with a cubic type architecture based on polyurethane can be almost reversibly deformed at values of technical deformation of more than 50 %. The developed approaches for obtaining polymer metamaterials and modifying their surface with calcium phosphate layer using an artificial interstitial fluid can increase the hydrophilicity of materials.

Synthesis of Magnesium- and Silicon-modified Hydroxyapatites by Microwave-Assisted Method

Nanopowders of hydroxyapatite (HA), modified by magnesium (MgHA) and by silicon (SiHA) were obtained by liquid-phase microwave synthesis method. X-ray diffraction and IR spectroscopy results showed that Mg2+ and SiO44− ions were present in the synthesized products both as secondary phases and as part of the HA phase. Whitlockite was found in the magnesium-modified HA (MgHA) and larnite was found in the silicon-modified HA (SiHA); ion substitution for both materials resulted in solid solutions. In the synthesized samples of modified HA, the increase of particle size of powders was in the order HA < SiHA < MgHA, which was calculated through data specific surface area and measured pycnometric density of the powders. The Lewis acid sites (Ca2+, Mg2+, Si4+) were present using spectral probes on the surface of the samples of HA, MgHA, and SiHA, and the acidity of these sites decreased in the order SiHA > MgHA > HA. The rates of calcium phosphate layer deposition on the surface of these materials at 37 °C in the model simulated body fluid solution showed similar dependence.

Characterization and Preparation of Calcium Phosphate Model Toothpaste for Tooth Enamel Remineralization

Calcium phosphates are excellent biomaterial for hard tissue regeneration and replacement. Recently, nanohydroxylapatite (HAp) has been intensively studied as remineralization agent for tooth enamel protection and remineralization. In this research, we developed model toothpaste composition, determined viscosity and investigated weather different processed – spray-dried (spCDHAp), lyophilized (lyoCDHAp), wet precipitated (paste-like consistence, pCDHAp) – calcium deficient hydroxyapatite (CDHAp) affect bovine tooth enamel remineralization. Model toothpastes components were CDHAp, 2-hydroxyethylcelluloce, glycerol and water. Viscosity varied from 2.5 to 40 Pa∙s. Model toothpastes with 20 wt% CDHAp showed thixotropic behaviour, thereby we examined them as potential tooth remineralization pastes. After in vitro remineralization enamel surface changes were detected, the texture of demineralized surface and bundles of HAp crystals were not observed. It was suggested, that new calcium phosphate layer was formed on the enamel. In conclusion, CDHAp is very promising material for enamel regeneration, but different pretreatment of CDHAp (resulting as different morphology of agglomerates) did not give distinctive remineralization results.

Composite Calcium Phosphate Coatings on Mg Alloy for Medicine

The high-tech method of creating anticorrosion calcium phosphate coating on the magnesium alloy MA8 (MgMnCe) has been developed. As was demonstrated by the volumetry method the sealing of the layer formed on the surface of Mg alloy using plasma electrolytic oxidation by superdispersed polytetrafluoroethylene substantially reduced the rate of the corrosion process. Here, the surface of the calcium phosphate layer containing hydroxyapatite (Ca/P = 1.61) remains biologically active. Studies of architectonics of the surface of innate immune cells have been performed in vitro.

Bioactivity and Physico-Chemical Properties of Composites on Basis of Hydroxyapatite with Lactic and Glycolic Acids Oligomers

A new methodin situfor producing of biocompatible composites based on hydroxyapatite and oligomers of lactic and glycolic acid is described. Their thermo-mechanical, physical-chemical and biological properties are studied as well. The formation of bonds between hydroxyapatite with lactic and glycolic oligomers in composites are confirmed by IR spectroscopy of the samples, including those obtained in the Soxhlet apparatus. The formation of calcium-phosphate layer on the composite's surface containing hydroxyapatite was shown by SBF-investigation. The scaffolds based on lactic acid oligomer do not stimulate formation of a calcium-phosphate layer and they are subjected to destruction by the way of hydrolysis.