Decomposition Of HA Research Articles

Research progress on the role of imbalanced high and low molecular weight hyaluronic acid in respiratory system inflammation caused by atmospheric particulate matter

Atmospheric particulate matter has an association with respiratory system inflammation, and low molecular weight hyaluronic acid (LMW-HA) is a key biomarker of inflammatory cascade reaction. This review summarized the possible pathways and biomarkers of atmospheric particulate matter causing respiratory system inflammation through high molecular weight hyaluronic acid (HMW-HA)/LMW-HA imbalance, including the synthesis and decomposition of HA, the reduction of particulate matter and HMW-HA, the increase of LMW-HA, and the relationship between LMW-HA and respiratory system inflammation. Furthermore, inhibitors and therapeutic drugs targeting certain biomarkers were further listed. This review could shed light on the mechanism of respiratory system inflammation caused by atmospheric particulate matter and the weak points that need attention in subsequent research.

Degradable magnesium-hydroxyapatite interpenetrating phase composites processed by current assisted metal infiltration in additive-manufactured porous preforms

• Introduction of novel hydroxyapatite-magnesium interpenetrating phase composites. • Produced by ceramic additive manufacturing and liquid metal infiltration. • Magnesium provides mechanical strength in the range of cortical bone. • An osteoconductive hydroxyapatite scaffold is generated after magnesium degradation. • The structural and biological properties are controlled through the digital design. This work explores ceramic additive manufacturing in combination with liquid metal infiltration for the production of degradable interpenetrating phase magnesium/hydroxyapatite (Mg/HA) composites. Material extrusion additive manufacturing was used to produce stoichiometric, and calcium deficient HA preforms with a well-controlled open pore network, allowing the customization of the topological relationship of the composite. Pure Mg and two different Mg alloys were used to infiltrate the preforms by means of an advanced liquid infiltration method inspired by spark plasma sintering, using a novel die design to avoid the structural collapse of the preform. Complete infiltration was achieved in 8 min, including the time for the Mg melting. The short processing time enabled to restrict the decomposition of HA due to the reducing capacity of liquid Mg. The pure Mg-base composites showed compressive yield strength above pure Mg in cast state. Mg alloy-based composites did not show higher strength than the bare alloys due to grain coarsening, but showed similar mechanical properties than other Mg/HA composites that have significantly higher fraction of metallic phase. The composites showed faster degradation rate under simulated body conditions than the bare metallic component due to the formation of galvanic pairs at microstructural level. Mg dissolved preferentially over HA leaving behind a scaffold after a prolonged degradation period. In turn, the fast production of soluble degradation products caused cell metabolic changes after 24 h of culture with not-diluted material extracts. The topological optimization and reduction of the degradation rate are the topics for future research.

Digital light processing porous TPMS structural HA & akermanite bioceramics with optimized performance for cancellous bone repair

In recent years, amorphous bioglass is used to improve the bioactivity of HA (Ca 10 (PO 4 ) 6 (OH) 2 ). Nevertheless, bioglass crystallizes and reacts with the matrix to form a complex phase composition during sintering, resulting in an unclear mechanism for tailoring the properties of HA bioceramics. In this work, TPMS structural HA ceramics fabricated by digital light processing (DLP) were doped by akermanite (Ca 2 MgSi 2 O 7 ) to better tailor the porosity, bioactivity and mechanical strength. After sintering above 1000 °C, Mg 2+ ions from akermanite substitute Ca 2+ ions in HA, leading to the decomposition of HA into β-TCP. This process increases the porosity of bioceramics. Additionally, liquid phases sintering caused by akermanite gives rise to the densification and enhancement of grain bonding, thereby reinforcing the mechanical strength of scaffolds. For in vitro bioactivity, as the content of akermanite increases from 0 wt% to 20 wt%, carbonated hydroxyapatite firstly deposits onto the surfaces of scaffolds and then disappears, because excessive Mg 2+ prevent the hydroxyapatite crystallization. Finally, bioceramics with 5 wt% and 10 wt% of akermanite and sintering at 1100 °C exhibit a high porosity of over 80% and an appropriate compressive strength of over 2 MPa, while achieving an enhanced in vitro bioactivity and good biocompatibility. After optimization, this kind of porous scaffolds can be well applied to the repair of cancellous bone defect.

Construction of corrosion resistant and osteogenic multiphase reinforced Titanium/hydroxyapatite nanocomposites prepared by spark plasma sintering

ABSTRACT Poor corrosion resistance and osseointegration of titanium/hydroxyapatite (Ti/HA) composites or coatings limit their application of long-term implants. In this study, spark plasma sintering was employed to fabricate Ti/HA nanocrystalline composites, in which HA was proposed to improve osseointegration of Ti alloys and surface-functionalized nanocarbons (graphene nanoflakes (GNFs) and carbon nanotubes (CNTs)) were proposed to improve corrosion resistance and osteogenicity of Ti/HA nanocomposites. The microstructures indicated that phase transition of Ti, HA decomposition and chemical reaction occurred during sintering and typical microstructural characteristics such as porosity, dislocations, polycrystalline compounds or secondary compounds were present in the Ti/HA nanocomposites. The electrochemical behavior showed that Ti/HA nanocomposites containing graphenes (0.5 GNFs and 0.4CNT/0.1GNFs) had better corrosion resistance compared to other composites (0.5 CNTs and nonreinforced). The embedded graphene acted as an efficient barrier against ionic diffusion, thus causing an effective shielding against corrosion. In vitro cytocompatibility and osteogenesis evaluation demonstrated that 0.4CNT/0.1GNF-reinforced Ti/HA nanocomposites led to optimal osteoblast adhesion and proliferation, support of osteogenic differentiation and osteogenic activity. In summary, overall, considering the corrosion resistance, cytocompatibility and osteogenesis of the Ti/HA nanocomposites, 0.4CNT/0.1GNF-reinforced Ti/HA nanocomposites had acceptable corrosion resistance and optimal cytocompatibility and osteogenicity, making it a potentially feasible bone implant biomaterial.

The Effect of Bioactive Glass and Sintering Conditions on the Properties of Titanium-Hydroxyapatite Composites

Titanium-hydroxyapatite (Ti-HA) based composites have been widely investigated as viable materials to be used in dentistry. However, sintering of these composites is very challenging due to decomposition of HA and oxidation of Ti. The objective of this study was to investigate the effect of incorporating a bioactive glass in Ti-HA composites sintered in different atmospheric conditions. The bioactive glass was prepared and added to different percentages of Ti-HA mixtures and divided into two groups. Samples in Group 1 were sintered with air atmosphere, while samples in Group 2 were sintered with vacuum furnace. All samples were later subjected to XRD, SEM, density, micro-hardness, and compression strength tests. XRD results showed that in Group 1, the major phases were assigned to Ti and HA while the minor phases were assigned to oxidised Ti. Whereas, Group 2 showed that the major phases were assigned to HA and the minor phases showed decomposition of HA to Ca3(PO4)2(TCP) and Ca4(PO4)2O (TTCP). Oxidized Ti was also present in this group. In terms of density, micro-hardness and compression strength, statistical analyses showed that samples in Group 1 have a significant difference (p = 0.000) as compared to those in Group 2. Sintering Ti-HA composites incorporated with BGby using air atmosphere furnace could reduce the decomposition of HA and oxidation of Ti, thus improve the density, micro-hardness and compression strength of the composites.

Effects of hydroxyapatite addition on the bioactivity of Ti-Nb alloy matrix composite fabricated via powder metallurgy process

This study investigates the bioactivity of titanium-niobium-hydroxyapatite (Ti-Nb-HA) composite prepared by mechanical alloying and powder metallurgy with variable HA content from 0 to 15 wt.%. Increasing the HA content weakened the X-ray diffraction intensity of β phase along with the noticeable presence of α phase and phases of TiO2, and Ti2P. The composite displayed good bioactivity in Hanks’ Balanced Salt Solution (HBSS) with the highest bioactivity exhibited by the 15 wt.% HA after a 30-day immersion with observed additional phases of CaTiO3 and CaO. Signs of HA decomposition, which led to an enhancement in the bioactivity, were remarked. The dispersion of HA particles in the Ti-Nb alloy matrix accelerated the apatite formation based on the accumulation of Ca, P and O elements on the composite surface. The presence of OH− and PO43- denoted the formation of calcium phosphate (apatite) with a hydrophilic surface. Based on the immersion test, only the 15 wt.% HA composite experienced a weight loss while the other composites gained weight.

Presintered Titanium-Hydroxyapatite Composite Fabricated via PIM Route

Ti6Al4V-HA composites have been recognized for their potential for biomedical implantation purposes. In the present study, Ti6Al4V-HA composites were fabricated by Powder Injection Molding (PIM) route. Ti6Al4V-HA feedstock at a ratio of 87:13 vol.% was prepared by using a binder system consisting of palm stearin (PS) and polyethylene (PE). The Critical Powder Volume Percentage (CPVP) value for Ti6Al4V-HA was 68 vol.%. Ti6Al4V-HA feedstock was developed at 66 vol.% powder loading. Ti6Al4V-HA feedstock showed pseudoplastic behaviour with a low viscosity and low activation energy of flow and was successfully injected into a tensile bar shape. The debinding process involved a solvent and thermal debinding operation. The debonded parts were sintered at 1300 °C, and the influence of the presintering stage on the physical and mechanical properties of the sintered parts was investigated. It was proven that the presintering stage was able to restrain the transformation of Ti6Al4V into Ti3Al (α2) as well as the decomposition of HA. These are key findings ideas for the designing of sintering parameters, where the decomposition of HA becoming the main problem in the sintering of Ti6Al4V-HA composites at a high temperature. The obtained results also showed that the sintered parts had a porous structure, which looked promising for their use in biomedical implantations. purposes.

Mechanical performance and in-vitro biological behaviors of boronized Ti6Al4V/HA composites synthesized by microwave sintering

The boronized Ti6Al4V/hydroxyapatite (HA) composites were synthesized by microwave sintering of the mixture of Ti6Al4V, HA and TiB2 powders at 950–1100 °C for 30 min, with an emphasis on the effects of sintering temperature on the properties of the resulting composites. It was found that at temperatures lower than 1050 °C, the composite specimens were not well sintered, causing high porosities in the composites. At 1050 °C, the Ti6Al4V grain boundaries were interconnected and intensified by TiB, resulting from the in situ reaction of TiB2 with Ti in the alloy. As the temperature increased to 1100 °C, there was apparent decomposition of HA to Ca3(PO4)2 which hindered complete densification of the composites. Because of these phase and microstructural transformations in association with the "lens effect" of microwave, the composite sintered at 1050 °C exhibited the optimal mechanical performance. Additionally, it possessed a small water contact angle, indicating its good hydrophilicity. By immersing this composite in the simulated body fluid (SBF), evident HA precipitation occurred on its surface, showing its great bioactivity. The findings confirmed that by controlling the sintering temperature properly, satisfactory mechanical performance and bioactivity can be obtained for this new type of biomaterial for implantation.

Microstructural, mechanical and biological properties of hydroxyapatite - CaZrO3 biocomposites

The biofunctionalization of metal implants with bioactive ceramics arises as an appealing strategy for promoting their osseointegration, without impairing implants’ good mechanical resistance. In this work, biocomposites of hydroxyapatite - CaZrO3 were obtained by rate controlled sintering and their microstructure, mechanical properties, biological as well as the effect of stoichiometric calcium zirconate dopant on the decomposition of HA were analysed. The results obtained showed that the addition of CaZrO3 stabilizes the hydroxyapatite at least up to 1300 °C and inhibits the appearance of the α- and β-TCP phases. Moreover, the mechanical properties of the hydroxyapatite were improved with 10 wt% of CaZrO3, despite the increase of porosity. The in vitro assays demonstrated that the biocomposites were biocompatible, since they favoured human osteoblast cells adhesion and proliferation. All the data obtained emphasize the potential of these biocomposites for the aimed biomedical application.

Crystallization behavior of low-cost biphasic hydroxyapatite/β-tricalcium phosphate ceramic at high sintering temperatures derived from high potential calcium waste sources

Abstract This paper reported the formation of biphasic hydroxyapatite, (HA) and β-tricalcium phosphate, (β-TCP) sintered at various sintering temperature from waste material. The phase stability of HA ceramic was investigated by imposing the high sintering temperature in order to study the transformation of the single phase of HA to biphasic HA/β-TCP ceramic. The evolution microstructure of HA and biphasic HA/β-TCP ceramic was studied at various sintering temperature reach up to 1400 °C. The single phase of HA was observed from 200 to 1200 °C and the secondary phase β-TCP appears due to the decomposition of partial HA at 1300–1400 °C. The optimum temperature for a single phase of HA was identified after sintering at 1200 °C to produce HA with high mechanical hardness about 5.11 GPa. This is clearly related to the phase stability and morphology of HA. The particles size of HA as-synthesized were recorded in nano range scale at ∼9 to 20 nm. However, the average particle sizes become larger and compact between ∼0.21 and ∼3.3 μm from 600 to 1200 °C. Thus, the sintering temperature gives an impact on the phase stability, microstructure and microhardness of HA derived from high potential waste sources.

Phase, mechanical and bioactivity properties of hydroxyapatite-calcium titanate composite

This research synthesizes hydroxyapatite-calcium titanate composites (HA-CT) using conventional route technique. The synthesis procedure involves two steps: (i) synthesis nanoparticle of HA and the fine powder of CT and (ii) synthesis the HA-CT composites ceramic, respectively. The nanoparticle of HA was synthesized through the co-precipitation method with control pH at 8. The fine powder of CT was prepared by molten salt synthesis. The densification, phase formation, microstructure, and mechanical properties of the HA-CT composite samples were investigated. The decreasing decomposition of HA in HA-CT composites at high temperature sintering is related to the increase of CT content. The HA-CT composites showed improvement properties of densification, Vickers hardness, Knoop hardness and Young’s modulus with the maximum value as 91.20 GPa for CT 0.15 mol% in HA-CT samples. The fracture toughness resulted in data shown that the fracture toughness behavior of the HA-CT composites was controlled by the CT contents as well as grain size and porosity. The information of microstructures by SEM analysis indicated that the CT content produced a notable decrease in grain size of the HA-CT composites.

Comparative study on microstructure and corrosion behavior of nanostructured hydroxyapatite coatings deposited by high velocity oxygen fuel and flame spraying on AZ61 magnesium based substrates

Hydroxyapatite coatings are biocompatible, osteoconductive and create a corrosion resistance surface on magnesium-based implants. Thermal decomposition of HA during thermal spraying limits its application. To overcome the challenges associated with thermal decomposition of HA during thermal spraying, high velocity oxygen fuel spraying with a good thermal stability for HA is proposed. In this work, the traditional flame spraying was compared to high velocity oxy-fuel (HVOF) for HA depositions on magnesium alloy substrates. The effect of process on microstructure, morphology, corrosion behavior and cellular response of HA layers were evaluated. X-ray diffraction analysis showed that the amount of secondary phases in the HVOF deposited sample was less than that in the flame sprayed coatings. Elemental weight percentage of calcium in corroded surfaces was 21% and 34.5% for HVOF and flame sprayed coatings, respectively. Contrary to the results of the electrochemical impedance spectroscopy measurements for HVOF coating performed during the early hours of immersion in the simulated body fluid (SBF), flame sprayed coating exhibited lower corrosion rate after 5 h immersion in SBF solution.

Influence of the addition of carbonated hydroxyapatite and selenium dioxide on mechanical properties and in vitro bioactivity of borosilicate inert glass

Five nanocomposite samples containing different percentages of carbonated hydroxyapatite (CHA), selenium dioxide (SeO2) and inert glass (IG) have been prepared using high-energy ball milling method with the aim of improving the in vitro bioactivity of these nanocomposites. Fourier transform infrared (FTIR) spectroscopy along with X-ray diffraction (XRD) technique was applied on both nanopowders and the sintered nanocomposites to record the structural changes and examine the resultant sintered phases. Mechanical properties were measured by ultrasonic non-destructive technique. In order to assess the bioactivity of the sintered specimens, they were soaked in simulated body fluid for 14 days and then, they were investigated by FTIR and scanning electron microscopy (SEM). Both FTIR and XRD spectra showed that the glasses encouraged the partial HA decomposition to tricalcium phosphate (TCP) and calcium silicate (CaSiO3) phases. The formation of the latter phase along with the remainder HA contents was responsible for good bioactivity and appropriate mechanical properties of the investigated nanocomposites. The successive addition of selenium dioxide to these nanocomposites led to further improvement of their bioactivity without any recorded changes in the mechanical properties. Based on the abovementioned results, the prepared nanocomposites can be used in various tissue-engineering applications.

Investigation the impact of ZTA addition on the properties of nano biogenic hydroxyapatite.

The target of the recent study is to achieve a significant inexpensive and eco-friendly way for getting ZTA/HA composites, based on the nano-HA derived from the eggshell biogenic source. Combining simultaneously the porous structure; which is considered as a bone formation key, with developed mechanical properties and adequate biocompatibility, is another purpose of this study. Furthermore, the impact of ZTA addition from 10-30 mass-%, fabricated by uniaxial pressing and sintering at 1200-1300 °C for 2 h, on the physical and mechanical properties, microstructure and phase composition of ZTA/HA composite bodies was investigated. The results demonstrated that the increasing of ZTA content increases the bodies' apparent porosity and decreases the bulk density due to the decomposition of HA into β-TCP. Where the formation of β-TCP possessed the predominant impact on the mechanical properties of the sintered ZTA/HA composites. ICP, SEM, EDX and thin film XRD results of composites containing 20 mass-% ZTA affirmed the excellent bioactivity of the bodies.

Microstructure, phase compositions and in vitro evaluation of freeze casting hydroxyapatite-silica scaffolds

Hydroxyapatite-silica (HA-SiO2) scaffolds with different SiO2 content (0, 2, 5 and 10wt% SiO2) were fabricated by freeze casting. After sintering, the scaffolds maintained the interconnected unidirectional pore channels by removing the frozen ice crystals via sublimation. X-ray diffraction (XRD) analysis indicated that SiO2 promoted the decomposition of HA to tricalcium phosphate (TCP), comprised of α-TCP and β-TCP, which became more apparent with the increase of SiO2 content. The microstructure observation of scanning electron microscope (SEM) showed that the scaffolds surface feature had great changes in terms of grain size and grain boundary with the addition of SiO2. Moreover, the addition of SiO2 could increase the porosity and pore size of the scaffolds, even allowing it to reach a maximum as the SiO2 content increased to 5wt%. Compression tests investigated the variation in the compressive strength of the scaffolds with the increase in the SiO2 content, which showed first decreasing and then increasing behavior. In vitro evaluation results in simulated body fluid (1.5×SBF) revealed that the introduction of SiO2 enhanced the growth rate of bone-like layer, especially the scaffold with 5wt% SiO2, which exhibited faster growth rate of bone-like layer than the other scaffolds. The XRD and fourier transformed infrared spectroscopy (FT-IR) characterization confirmed that the bone-like layer formed on the scaffold surface was a carbonate-containing hydroxyapatite bone-like layer.

Wet chemistry approach to the preparation of tantalum-doped hydroxyapatite: Dopant content effects

Tantalum-doped hydroxyapatite (Ta-doped HA) nanopowders with different Ta contents were synthesized by a wet-chemical precipitation route. The structure modification and charge compensation mechanism were investigated by various characterization techniques. Due to the smaller size of tantalum ions compared to the Ca2+ size, it was assumed that the tantalum ions occupy either the Ca2+ and/or the interstitial positions in the HA lattice, where the charge imbalance from to this substitution was compensated by the Ca2+ vacancies. From the XRD patterns, the as-synthesized nanopowders were poorly crystalline apatite in the absence and presence of different dopant contents. The hexagonal HA and tricalcium phosphate (β-TCP) phases as biphasic calcium phosphate mixtures were formed after heating at 900°C. In addition to the β-TCP phase, minor extra phases such as calcium oxide (CaO) and calcium pyrophosphate (Ca2P2O7) were identified from the HA decomposition. The FTIR results indicated that the decrease of structural hydroxyl groups depended on both tantalum oxyanions and carbonate contents. In the XPS profile, the Ta 4f peak of the doped sample could be decomposed into four main components, which showed different oxidation states for tantalum (TaO2 oxide). According to the TEM observations, the doped calcined powder at 900°C was composed of uniform nanoneedles with an average length and width of 120 ± 50 and 10 ± 5nm, respectively.

Sintering effects of mullite-doping on mechanical properties of bovine hydroxyapatite

In this study, sintering effects on microstructural behavior of bovine derived hydroxyapatite doped with powder mullite are considered in the temperature range between 1000°C and 1300°C. Results show that maximum values of both compressive strength and microhardness are achieved in the samples sintered at 1200°C for all mullite additions of 5, 7.5, 10 and 12.5wt%. Moreover, above 1000°C, decomposition of HA and new phase formations such as whitlockite and gehlenite play a major role in both compressive strength and microhardness properties which increase up to 10wt% mullite reinforcement.

Thermal stability of a modified sol-gel derived hydroxyapatite nanopowders

Hydroxyapatite Ca10(PO4)6(OH)2 (HA) powder was successfully synthesized by a modified sol-gel method using a solution of calcium nitrate in ethanol, along with a solution of diammonium hydrogen phosphate in water and NH4OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The powder was subjected to furnace and microwave heating to compare the decomposition of HA and study the crystallite sizes. It was found that microwave heated powders were pure HAP up to 230°C with absence of secondary phases. However, XRD patterns show that furnace heated powders convert completely to β-TCP when treated at 750°C and 1000°C. This result was confirmed by the absence of hydroxyl bands in the FT-IR spectra for these temperatures.

Microstructure, stability and biocompatibility of hydroxyapatite – titania nanocomposites formed by two step sintering process

In the present work, we report the characterization of TiO2-hydroxyapatite (HA) nanocomposites obtained by a two-step sintering (TSS) process of a mixture of HA and titanium hydride (TiH2) powders. The reactions underwent by TiH2 in the presence of HA and hydrogen release, and subsequently, titanium oxidation was examined by thermal analysis. A longer holding time in the second sintering stage enabled obtaining a homogenous TiO2-HA (36% rutile) composite with a thermal expansion coefficient of 11.46·10−6C−1 in the 40–1000°C range. Unconventional TSS process hinders HA decomposition to detrimental tricalcium phosphate (TCP). Wear rate of ceramics was determined by tribological measurements and the material biocompatibility was evaluated using MTT assay. Overall, cell viability results correlated with morphological observations indicated a good biocompatibility of HA-based composites at all tested concentrations. Incorporation of the TiO2 phase in HA by TSS process was found to be an efficient way to prepare bioceramics with improved performances.

Spin-coating synthesis and characterization of Zn-doped hydroxyapatite/polylactic acid composite coatings

Abstract Zn-doped hydroxyapatite/polylactic acid (HA/PLA) composite coatings fabricated by spin-coating technique have rarely been studied by other researchers in recent years. In this study, Zn-doped hydroxyapatite (Zn-doped HA) powder were synthesized by chemical precipitation method, and then Zn-doped hydroxyapatite/polylactic acid (Zn-doped HA/PLA) composite coatings were coated on stainless steel substrates using a spin-coating technique for the first time. The effects of heat treatment in air at 600 °C on the composition and morphology of Zn-doped HA/PLA composite coatings with a series of molar ratios of zinc (0 mol%, 5 mol%, 10 mol%, 15 mol% and 20 mol%) were studied. The obtained samples were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results showed that Zn 2 + ions had replaced the partial Ca 2 + ions and were doped into hydroxyapatite lattice successfully. The synthetic hydroxyapatite nanoparticles showed rod-like morphology, whereas the substitution of the Zn ions restrained the growth of Zn-doped HA crystal and decreased its size. The surface morphology of Zn-doped HA/PLA composite coatings after sintering at 600 °C for 1 h exhibited a uniform, porous structure with a thickness of 60 μm or so. The introduction of PLA in composite coatings could keep metal substrates from catalyzing the decomposition of HA caused by high temperature heat treatment.