MODIFICATION OF CALCIUM PHOSPHATE FOAM CERAMICS WITH BIOAPATITE IN SBF SOLUTION

Получена многофазная кальцийфосфатная пенокерамика, представленная Д -трикальцийфосфатом (65 %) и Д -пирофосфатом кальция (25 %), включающая гидроксиапатит ( 5 %) и а -трикальцийфосфат ( 5 %), пористостью 60 - 64 % со сквозной архитектурой пенополиуретана. Нанесение слоя гидроксиапатита приводило к увеличению содержания гидроксиапатита до 25 %, а -трикальцийфосфата до 40 %, и повышению статической прочности до 0,03 МПа при снижении пористости до 49 %. Нанесение второго слоя гидроксиапатита способствовало повышению содержания гидроксиапатита до 40 %, статическая прочность достигала 0,05 МПа при пористости 40%. Формирование биоапатита в виде слоя «пеносфер» размером от 2 до 10 мкм происходило в процессе модифицирования всех видов пенокерамики в растворе SBF в течение 21 - 28 суток. Модифицированная кальцийфосфатная пенокерамика, обогащенная а -трикальцийфосфатом и гидроксиапатитом, характеризовалась максимальной статической прочностью 0,08 МПа при пористости 38%. The multiphase calcium phosphate foam ceramics, represented by р -tricalcium phosphate (65 %) and р -calcium pyrophosphate (25 %), including hydroxyapatite (5 %) and а -tricalcium phosphate (5%), with 60 - 64% porosity and a through architecture of polyurethane foam was obtained. The application of a layer of hydroxyapatite led to an increase in the content of hydroxyapatite to 25 %, а -tricalcium phosphate to 40%, and an increase in static strength to 0,03 MPa with a decrease in porosity to 49%. The application of the second layer of hydroxyapatite promoted an increase in the content of hydroxyapatite to 40%, the static strength reached 0,05 MPa at a porosity 40 %. The bioapatite formation in the shape of «foam spheres» with a size from 2 to 10 pm occurred in the process of modifying all types of foam ceramics in a SBF solution during 21 - 28 days. The modified calcium phosphate foam ceramics enriched with а -tricalcium phosphate and hydroxyapatite, was characterized by the maximum static strength 0,08 MPa at a porosity 38 %.

APATITES FORMATION ON ELECTRODEPOSITED CALCIUM PHOSPHATES IN THE Ca(NO3)2 / NH4H2PO4 AND CаCOз / Ca(H2PO4)2 SYSTEMS

Методом электрохимического осаждения на титановых пластинах при комнатной температуре в двухэлектродной ячейке при постоянной плотности тока 30 мА/см и времени осаждения 10 мин получены кальцийфосфатные покрытия: брушитные в системе Ca (NO )/ NH H PO при pH = 4 и композитные (брушит/кальцит/апатит) в системе CaCOjCa (HPO ) при pH = 5. Выдерживанием кальцийфосфатных покрытий обоих типов в модельном растворе SBF в течение 1 месяца определяли апатитообразующую способность (биоактивность). Новообразованный аморфизированный апатитовый слой после термообработки при 800°С кристаллизовался в Д -трикальцийфосфат/гидроксиапатит на брушитных покрытиях и в гидроксиапатит на композитных покрытиях за счет присутствия кальцита, карбонат-ионы которого являются инициаторами образования гидроксиапатита, а также апатитных наночастиц в исходном покрытии. Полученные кальцийфосфатные покрытия перспективны в качестве биопокрытий повышающих остеоинтеграцию металлических имплантатов. Calcium phosphate coatings on titanium plates were obtained by electrochemical deposition at room temperature in a two-electrode cell at a constant current density of 30 mA/sm and a deposition time of 10 min, and brushite coatings from Ca (NO )/NHHPO system at pH = 4, and composite (brushite/calcite/apatite) coatings from the CaCO/ Ca(HPO) system at pH = 5. The apatite-forming ability (bioactivity) was determined by soaking both types of calcium phosphate coatings in a model SBF solution during month. The newly formed amorphized apatite layer after heat treatment at 800 °С crystallized into p -tricalcium phosphate/hydroxyapatite on brushite coatings and hydroxyapatite on composite coatings due to the presence of calcite, whose carbonate ions initiate formation of hydroxyapatite, as well as apatite nanoparticles in the initial coating. The obtained calcium phosphate coatings are promising as biocoatings capable to increase osseointegration of metal implants.

Research of the biological activity of cooper-doped hydroxyapatite samples

The paper considers in vitro and in vivo research of the biological activity of cooper-doped hydroxyapatite samples (CuHAp). Samples were obtained by microwave-assisted liquid-phase synthesis. Kinetic of the calcium ions sedimentation on CuHAp samples from SBF solution does not depend from cooper ions quantity. Implantation of CuHAp samples induces local rejection reaction. The reaction severity incises with increase of cooper ions quantit.

Enhancing Ossiointegration And Corrosion Properties of Ti6Al4V Alloy By Coating With Chitosan – Collagen- Hydroxyapatite For Biomedical Applications

In this research, Ti-6Al-4V alloy samples were coated with 4 gm strontium hydroxyapatite with 2 gm from chitosan and (2,4,6) gm from collagen and the samples heat treated at 150 ºC in muffle furnace for one hour under air atmosphere. The sample were tested by XRD,FTIR,SEM and corrosion test was also achieved. The samples were immersed in a laboratory prepared simulated body fluid (SBF) solution for two weeks, the samples treated at 150 ºC in muffle furnace for one hour under air atmosphere to get more bonding for new layer . The samples tested by XRD,FTIR,SEM and corrosion test was also achieved after immersing . The sample coated with 6 gm collagen showed maximum growth of hydroxyapatite formed from simulated body fluid SBF and corrosion characteristics was much improved.

Equisetum Hyemale - Derived Unprecedented Bioactive Composite for Hard and Soft Tissues Engineering

Although Bioactive Glasses (BG) has been progressively optimized, their preparation still uses toxic reagents and calcination at high temperatures to remove organic solvents. The drawbacks related to the BG synthesis were overcome by treating the ashes from the Equisetum hyemale plant in an ethanol/water solution to develop a bioactive composite [glass/carbon (BG-Carb)]. The BG-Carb was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and its chemical composition was assessed by inductively coupled plasma – optical emission spectroscopy (ICP-OES). Brunauer-Emmett-Teller (BET) gas adsorption analysis showed a specific surface area of 121 m2 g-1. The formation of hydroxyapatite (HA) surface layer in vitro was confirmed by Fourier-transform infrared spectroscopy (FTIR)analyse before and after immersion in simulated body fluid (SBF) solution. The Rietveld refinement of the XRD patterns and selected area electron diffraction (SAED) analyses confirmed HA in the sample before the immersion in SBF solution and after immersion in SBF solution; and increase of the HA layer on the sample surface, after the immersion in SBF solution. The BG-Carb samples showed no cytotoxicity on MC3T3-E1 cells and osteo-differentiation capacity similar to the positive control. Altogether, the BG-Carb material data reveals a promising plant waste-based candidate for hard and soft tissue engineering.

The Effect of Liquid Phase Concentration on the Setting Time and Compressive Strength of Hydroxyapatite/Bioglass Composite Cement

Composite scaffolds of hydroxyapatite (HAp) nanoparticles and bioactive glass (BG) have been applied as appropriate materials for bone tissue engineering. In this study, hydroxyapatite/bioglass cement in different ratios was successfully fabricated. To prepare HAp and HAp/BG cement, synthesized HAp and HAp/BG powder were mixed in several ratios, using different concentrations of sodium hydrogen phosphate (SP) and water as the liquid phase. The liquid to powder ratio used was 0.4 mL/g. The results showed that setting time increased with BG content in the composite. The results also showed that with the addition of bioglass to the HAp structure, the density decreased and the porosity increased. It was also found that after immersion in simulated body fluid (SBF) solution, the compressive strength of the HAp and HAp/BG cements increased with BG concentration up to 30 wt.%. SEM results showed the formation of an apatite layer in all selected samples after immersion in SBF solution. At 30 wt.% BG, greater nucleation and growth of the apatite layer were observed, resulting in higher bioactivity than pure HAp and HAp/BG in other ratios.

Slurry Coating of Hydroxyapatite on Zirconia Substrate

Zirconia dental implants require excellent biocompatibility and high bonding strength. In this study, we attempted to fabricate biocompatible zirconia ceramics through surface modification by hydroxyapatite (HA) slurry coating. A hydroxyapatite slurry for spin coating was prepared using two sizes of hydroxyapatite particles. The hydroxyapatite slurry was obtained by adjusting the solid loading, pH range, and dispersant content. The surface roughness of the HA-coated layers on the zirconia substrate depended on the change in microstructural evolution and coating thickness. With repeated coating, the coating thickness gradually increased for both small and large particles. The specimen with two coatings had the maximum surface roughness but displayed different values depending on the size of the HA particles. High surface roughness (Ra; 0.49 μm) could be obtained from the slurry of small particles compared with that of the large particles (Ra; 0.35 μm). During a 14 days in vitro experiment in SBF solution at pH 7.4, no changes were observed in the surface microstructure of the HA coating layer on the zirconia substrate.

Bioactivity Improvement of Zirconia Substrate by Hydroxyapatite Coating Using Room Temperature Spray Processing

Zirconia ceramics has a bioinert property with low bioactivity. So, it is necessary to improve its low bioactivity by the surface modification using effective coating methods. In this study, we fabricated the hydroxyapatite-coated zirconia substrate by room temperature spray processing to improve the bioactivity of the zirconia implant and investigated its coating effect on the biological performance of zirconia substrate via an in vitro test in simulated body fluid (SBF) solution. Before the room temperature spray coating was completed, size-controlled hydroxyapatite powder that had an average size of 4.5 μm, was obtained by the calcination and milling of a commercial powder. By controlling the processing parameters, such as spraying distance, and deposition cycles, we fabricated homogeneous and dense hydroxyapatite coatings on zirconia substrate. Surface morphology, coating thickness, and microstructure were dependent on deposition cycles, and were related to surface roughness and bioactivity. Zirconia substrates with wave-patterned and roughened hydroxyapatite coatings demonstrated high bioactivity in their in vitro tests. Via the immersion test in an SBF solution, surface dissolution and new precipitates of hydroxyapatite were observed on coated zirconia substrate, indicating the degree of bioactivity.

Electrochemical evaluation of the hydroxyapatite coating synthesized on the AZ91 by electrophoretic deposition route

The hydroxyapatite layer was deposited on the commercial magnesium alloy of AZ91 by electrophoretic deposition route, and the corrosion behavior of applied layers was studied by polarization and electrochemical impedance spectroscopy at the Simulated Body Fluid (SBF) solution. The best corrosion resistance improvement was obtained for the sample synthesized at 40 V within 4 minutes. Also, the morphology of coated samples was studied by atomic force microscopy (AFM) and the surface parameters were measured. It could be concluded that the calculated values for surface parameters including surface roughness, maximum peak height, maximum pit depth, and maximum peak have a meaningful relationship with corrosion resistance.