Stereolithographic fabrication of three-dimensional permeable scaffolds from CaP/PEGDA hydrogel biocomposites for use as bone grafts.

Polyethylene glycol diacrylate-based hydrogels filled with calcium phosphates (CaP, Ca/P < 1.5) were stereolithographically fabricated as three-dimensional permeable biocomposites for bone tissue regeneration, probed by several instrumental techniques (including scanning electron microscopy, infrared and UV-vis spectroscopy), and subjected to rheological/mechanical property analysis. As the CaP content increased from 0 to 10 wt%, Young's modulus and mechanical strength increased from 4 to 11 kPa and from 34 to 167 kPa, respectively.

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

A technique for colloidal forming of CaPO macroporous bioceramics, based on low-pressure injection molding (LPIM) of a glycerol-water slip containing CaPO and Ca(НPO) into a plastic mold fabricated via FDM 3D-printing, was proposed. Chemical reaction between the solid phases of the water containing slip - CaPO and Ca(НPO), resulting in brushite (CaHPO·2HO) 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(PO) and sintered in liquid-phase regime, demonstrated a compressive strength of 1.

Experimental Evaluation of the Properties of 3D Porous Bone Substitute Based on Calcium Phosphate on the Model of Monocortical Diaphysial Femur Defect in Rats.

A new alloplastic high-permeable material based on tricalcium phosphate with Kelvin architectonics created by stereolithographic 3D-printing was studied in vivo. A monocortical defect of the femur was modeled in rats and the material was implanted into the defect area. In 24 weeks, the animals were euthanized and histological examination of the defect area was performed.

The Interplay of manganese and nitrate in hydroxyapatite nanoparticles as revealed by pulsed EPR and DFT.

The interplay of oppositely charged substitutions in the structure of hydroxyapatite (HAp) nanopowders is investigated on the atomic level by pulsed electron paramagnetic resonance (EPR) technique and ab initio density functional theory calculations. Benefits of EPR to determine Mn(2+) ions in nano-HAp samples are demonstrated. A simple approach based on the measurements of electron spin relaxation times allowed observing the strong influence of fast-relaxing Mn(2+) ions on the relaxation characteristics of the nitrate ions (NO3(-)/NO3(2-)) incorporated in trace amounts.

Combination of EPR measurements and DFT calculations to study nitrate impurities in the carbonated nanohydroxyapatite.

We demonstrate the application of the combined experimental-computational approach for studying the anionic impurities in hydroxyapatite (HAp). Influence of the carbonation level (x) on the concentration of the NO3(2-) radicals in the HAp nanocrystals of Ca10-xNax(PO4)6-x(CO3)x(OH)2 with x in the range 0 < x < 2 and average sizes of 30 nm is investigated by different analytical methods including electron paramagnetic resonance (EPR). Stable NO3(2-) radicals are formed under X-ray irradiation of nano-HAp samples from NO3(-) ions incorporated in trace amounts during the wet synthesis process.