Morphology Of Apatite Research Articles

The apatite-forming ability of bioactive glasses – A comparative study in human serum and Kokubo's simulated body fluid

Currently, the apatite-forming ability evaluation of a biomaterial employs Kokubo's simulated body fluid (SBF) as a testing medium. As the conventional SBF simulates only the ionic composition and pH of human serum (HS), this study aimed to compare the apatite formation in SBF and HS on the sol-gel-derived bioglass (BG) 83S2 and commercial 45S5 as well as to verify the influence of preincubation of BG in both fluids on cytocompatibility towards human fetal osteoblast cell line hFOB 1.19. The apatite formation in HS was hindered, regardless of the type of used BG. Relatively higher apatite-forming ability was noticed for BG83S2. In direct contact test, both BGs were cytocompatible towards osteoblasts, regardless of the type of used fluid. In the case of extracts; however, only the extract obtained from BG83S2 preincubated in HS did not show the cytotoxic effect. The evaluation of apatite-forming ability in SBF appears to be a fast screening method for comparing the apatite-forming ability of various bioglasses. Nonetheless, SBF is unable to precisely imitate the morphology and crystallinity of apatite observed during the assay in HS, as well as it does not mimic the changes in profiles of osteogenic ions.

Temperature effect in physicochemical and bioactive behavior of biogenic hydroxyapatite obtained from porcine bones

Biogenic hydroxyapatite (BHAp) is a widely used material in the biomedical area due to its similarities with the bone tissue mineral phase. Several works have been spotlighted on the thermal behavior of bone. However, little research has focused on determining the influence of calcination temperature in the physicochemical and bioactive properties of BHAp. In this work, a study of the physicochemical properties’ changes and bioactive response of BHAp produced from porcine femur bones using calcination temperatures between 900 to 1200 °C was conducted. The samples’ structural, morphological, and compositional changes were determined using XRD, SEM, and FTIR techniques. XRD results identified three temperature ranges, in which there are structural changes in BHAp samples and the presence of additional phases. Moreover, FTIR results corroborated that B-type substitution is promoted by increasing the heat treatment temperature. Likewise, samples were immersed in a simulated biological fluid (SBF), following the methodology described by Kokubo and using ISO 23317:2014 standard, for 3 and 7 days. FTIR and SEM results determined that the highest reaction velocity was reached for samples above 1000 °C, due to intensity increasing of phosphate and carbonate bands and bone-like apatite morphologies, compared to other temperatures evaluated.

Mafic microgranular enclaves from the Tieshan batholith, eastern China: Implications for petrogenesis of magma associated with Fe-Cu skarn mineralization

Mineralogy, geochemistry, and geochronology of the mafic microgranular enclaves (MMEs) and their host diorite from the Tieshan batholith, Edong district, eastern China, were studied to constrain their petrogenesis and relationship with Fe-Cu skarn mineralization. The MMEs are diorite in composition and characterized by mixed apatite morphologies (elongated thin needles and stubby prismatic form) and bladed biotite, as well as clots of host diorite and megacrystic alkali-feldspar xenocrysts. The MMEs have similar zircon U-Pb age as their host diorite (~139 Ma). Most of the major and trace elements of the MMEs show a linear trend on Harker diagrams and plot along the low-silica trend of the host diorite. They are also characterized by enrichment of LREE and large ion lithophile elements (LILE), but are depleted in high field strength elements (HFSE). The MMEs display similar initial Sr isotopes and εNd(t), and slightly lower εHf(t) compared to that of host diorite. These results indicate that the Tieshan batholith formed via partial melting of an enriched lithospheric mantle, which is believed to be in equilibrium with a garnet-bearing residue (>50 km), followed by contamination of low crustal materials and fractional crystallization, whereas the MMEs appear to be the products of magma mixing. The presence of Cu- and Ni-bearing minerals in the MMEs probably indicates upper mantle or lower crust accumulation of sulfide which may have played a key role in controlling the formation of the parental magma associated with the skarn-porphyry Cu deposit (148 to 135 Ma) from the Middle-Lower Yangtze River metallogenic belt (MLYRMB). In contrast, the thinner, normal crust (~30 km) at ~ 130 Ma, believed to be in equilibrium with a plagioclase-rich residue, was either unsuitable for producing Cu-bearing accumulations or failed to transfer the deep accumulations to shallower levels to form Cu-bearing skarn systems, resulting in Fe-only mineralization. This may imply that skarn-porphyry Cu deposits prefer to form under > 50 km crustal settings, whereas Fe skarns may preferentially occur under normal (~30 km) crustal thickness.

Heparin as a biomimetic template on nanoapatite rods with tunable aspect ratio: synthesis and biocompatibility

In this study, heparin was used as a natural organic template to prepare nanoscale needle- or rod-like (nanorod) carbonate-based apatite. The characteristic phase and selected area electron diffraction patterns confirmed that the nanorods grew in the preferred crystallographic orientation, that is, the [0001] direction of the c-axis of apatite. As a result of the heparin-templated apatite nanoparticles, the apatite morphological variations revealed that the presence of heparin was potentially incorporated with Ca2+ cations, thereby inhibiting a-axis growth, increasing the aspect length-to-width ratio of the apatite nanorods, and effectively changing the precipitate form into uniform nanoscale rod-like shaped apatite. From the infrared spectra, the hexagonal structure template mediated by heparin was B-type carbonated calcium-deficient hydroxyapatite (CDHA), which indicated that heparin demonstrated regulated growth in the processed template of carbonated CDHA. Cell viability analysis showed that cytotoxicity was caused by the influence of specific nanoscale aspect ratios of the rod-like apatite morphology or by tuning a large aspect ratio of rod-like shaped apatite with a large quantity of heparin incorporation, resulting in fast ion dissolution by rapidly raising the pH. Overdosed heparin used as a template to prepare apatite nanoparticles led to highly negatively charged nanorods that caused cytotoxicity. We propose the optimal group of synthetic HAP@Hep25K within the proper heparin concentration, which showed the intended morphology of apatite nanorods and exhibited biocompatibility.

Preparation, characterization, and in vitro and in vivo biocompatibility evaluation of polymer (amino acid and glycolic acid)/hydroxyapatite composite for bone repair

A composite of hydroxyapatite (HA) and polymers prepared from amino acids and glycolic acid (PAG) was synthesized using an in situ melting polycondensation method. The in vitro degradability and bioactivity of the composite were evaluated, as well as its in vitro and in vivo biocompatibility based on subcutaneous and osseous implantation of samples in New Zealand white rabbits for 8 weeks. The results showed that the PAG/HA composite had higher degradability than PAG and showed a typical apatite morphology after immersion in simulated body fluid for 5 d. Both the PAG/HA composite and PAG alone showed excellent in vitro biocompatibility. In the rabbit model, PAG/HA composite could induce formation of new bone tissue after 4 weeks implantation, mainly owing to the excellent in vivo bioactivity of the implant. These results suggest that PAG/HA composites have the potential to guide bone regeneration and could be used as biodegradable biomaterials for bone repair.

Characterization of weld seam surface and corrosion behavior of laser-beam-welded AISI 2205 duplex stainless steel in simulated body fluid

In this study, AISI 2205 duplex stainless steel was joined with laser welding. Base material and laser-welded samples were kept in simulated body fluid (SBF) for 1, 3, 7, 14, 21, and 28 days. This research investigated microstructure, hydroxyapatite (HA) structure formed on surfaces, surface topography, and corrosion properties of samples which were kept in SBF. Characterization studies were performed by using microhardness, optical microscope, macroscope, SEM–EDS, XRD, and atomic force microscope. According to results, it was found out that HA accumulation was higher on base material surface when compared to weld seam surface, and also calcium-deficient carbonate HA structure with low crystallinity was observed on all surfaces. Very low corrosion rates due to very low weight losses were detected in all samples kept in SBF. The results showed us that heat input changes had an important effect on surface roughness values (Ra), apatite morphology on weld seam surfaces, and corrosion behaviors. Overall, it is considered that laser-welded duplex stainless steel can be used as an implant material depending on surface characterization and corrosion behaviors.

Additively Manufactured Polyetheretherketone (PEEK) with Carbon Nanostructure Reinforcement for Biomedical Structural Applications

This study is focused on carbon nanostructures (CNS), including both carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), reinforcement of medical‐grade polyetheretherketone (PEEK), and in vitro bioactivity for biomedical structural applications. CNS/PEEK scaffolds and bulk specimens, realized via fused filament fabrication (FFF) additive manufacturing, are assessed primarily in the low‐strain linear‐elastic regime. 3D printed PEEK nanocomposites are found to have enhanced mechanical properties in all cases while maintaining the desired degree of crystallinity in the range of 30–33%. A synergetic effect of the CNS and sulfonation toward bioactivity is observed—apatite growth in simulated body fluid increases by 57% and 77%, for CNT and GNP reinforcement, respectively, doubling the effect of sulfonation and exhibiting a fully‐grown mushroom‐like apatite morphology. Further, CNT‐ and GNP‐reinforced sulfonated PEEK recovers much of the mechanical losses in modulus and strength due to sulfonation, in one case (GNP reinforcement) increasing the yield and ultimate strengths beyond the (non‐sulfonated) printed PEEK. Additive manufacturing of PEEK with CNS reinforcement demonstrated here opens up many design opportunities for structural and biomedical applications, including personalized bioactivated surfaces for bone scaffolds, with further potential arising from the electrically conductive nanoengineered PEEK material toward smart and multifunctional structures.

Evaluation of strontium-containing hydroxyapatite as bone substitute in sheep tibiae.

With the advancement of research in biomaterials, it has been suggested that the best osteoconductivity of hydroxyapatite would be achieved if its crystal were closer to the structure, size and morphology of biological apatite, that is why nano-hydroxyapatite (nano-HA) is of great importance. current interest. Strontium ions are known to reduce bone resorption, induce osteoblastic activity and stimulate bone formation. The aim of this study was to evaluate biocompatibility and osteoconduction in surgical defects filled with nano-hydroxyapatite microspheres containing 1% strontium (nano-SrHA), stoichiometric nano-HA microspheres (nano-HA) compared to the clot (control) . Four Santa Inês sheep, weighing an average of 32 kg, were anesthetized and submitted to three 2 mm diameter perforations in the medial face of the tibia. The surgical defects were filled with blood clot, microspheres of Sr-HA 1% and microspheres of HA. After 30 days the samples were drawn (6 mm), decalcified, processed for inclusion in paraffin and stained with hematoxylin and eosin (HE) for histological evaluation with light microscopy. All groups revealed bone neoformation from the periphery to the center of the defect, with the nano-SrHA group being less intense among those studied. Presence of a discrete mononuclear inflammatory infiltrate in all experimental groups. Giant foreign body cells were only observed in the HA group. Areas of bone neoformation were observed in close contact with both biomaterials. According to the results obtained, microspheres of HA and SrHA 1% are biocompatible and have osteoconductive properties.

Typomorphic characteristics of apatite morphology of carbonate-bearing variations of complex ores in the context of Kovdor deposit

The authors highly appreciate consultative support provided by Professor B.I. Pirogov both in the process of analytical generalization of the obtained results and while the paper writing.

Effect of surface chemical modifications on the bioactivity of carbon fibers reinforced epoxy composites

Carbon fibers reinforced epoxy (CF/epoxy) composites have been used in orthopedic and dental implants. However, the inert surface of CF/epoxy composites cannot show ability of forming direct bone bonding with autologous bone during implantation. In order to improve the bioactivity of CF/epoxy composites, the different chemical modifications (concentrated sulfuric acid (97 wt%), CaCl2 solution, concentrated sulfuric acid (97 wt%) + CaCl2 solution) were used to modify its original surface. The bioactivity of modified CF/epoxy composites was evaluated by in vitro apatite formation ability in simulated body fluids (SBF). The result showed that -SO3H and Ca2+ were introduced on the of sample surface after chemical modification. Samples modified with concentrated sulfuric acid (97 wt%) and CaCl2 solution showed the best bioactivity. In addition, a uniform and dense apatite coating was formed on the surface of functionalized CF/epoxy composites after soaking in SBF and the presence of -SO3H would significantly improve the bond between the coating and the substrate. The transformation process of apatite morphology during its formation and the mechanism of apatite formation on the functionalized CF/epoxy composites were also analyzed systematically.

Bioorthogonal surface modified α-TCP-based bone filler for enhancement of apatite formation and bioactivity

The aim of the present study was to investigate the effect of click chemistry reactants on morphology and physico-chemical properties of alpha tricalcium phosphate (α-TCP)-based powders. The powders were synthesized by solid-state reaction. The powders were modified with azide and cycloalkyne to form triazole as a consequence of reactions of these molecules. The presence of the band related to the triazole ring and the click molecules in powder structure was confirmed by Fourier transform infrared (FTIR) and Liquid chromatography- mass spectroscopy (LC-MS) analyses. Based on scanning electron microscopy (SEM) observations, the modified powder exhibited a different microstructure and morphology of apatite precipitates after one day and 7 days of soaking in distilled water and SBF solution, respectively, with respect to unmodified powder. According to the acellular in vitro test, X-ray diffraction (XRD) patterns represented triple characteristic peaks of hydroxyapatite (HA) in modified powder compared with control. Besides, the tendency of conversion of α-TCP to HA is more enhanced for modified powder as well. The SEM analysis depicted the plate-like and needle-like morphology of HA on the surface of modified and control powders, respectively. Since plate-like morphology of HA enhances bone generation and is found in trabecular bone, therefore, a future design can be considered for triazole-modified α-TCP-based fillers as good candidates for bone substitute application.

Characterization and biological properties of a novel synthesized silicon-substituted hydroxyapatite derived from eggshell.

In the present study, the effect of adding different concentrations of silicon on physical, mechanical and biological properties of a synthesized aqueous precipitated eggshell-derived hydroxyapatite (e-HA) was evaluated. No secondary phases were detected by X-ray diffraction for the specimens e-HA and e-HA containing silicon (Si-e-HAs) before and after heating at 1200°C. A reduction in the crystallite size and a-axis as well as an increase in c-axis was occurred when silicon replacement was happened in the structure of e-HA. The presence of Si-O vibrations and carbonate modes for Si-e-HAs was confirmed by Fourier transform infrared spectroscopy analysis. The range of porosity and density was varied from 25% and 2.4 g cm-3 to 7% and 2.8 g cm-3 for e-HA and Si-e-HAs. The values of Young's modulus ( E) and compressive strength were varied for e-HA and Si-e-HAs. The porous structure of the samples was reduced when they were heated as e-HA kept the porous microstructure containing some dense areas and Si-e-HAs possessed a rough surface including slight levels of microporosity. The acellular in vitro bioactivity represented different apatite morphologies for e-HA and Si-e-HAs. The G-292 osteoblastic cells were stretched well on the surface with polygon-shaped morphology for 0.8Si-e-HA after 7 days of culture. According to MTT assay and alkaline phosphatase test, the maximum cell activity was related to 0.8Si-e-HA. The minimum inhibitory concentration for 0.8Si-e-HA and e-HA was estimated to be about 3.2 and 4.4 mg/mL, respectively. In overall, the sample 0.8Si-e-HA exhibited a higher bacteriostatic effect than e-HA against gram-negative bacterial strain Escherichia coli.

FTIR and electron microscopy observed consequences of HCl and CO2 interfacial interactions with synthetic and biological apatites: Influence of hydroxyapatite maturity

HCl and CO2 are active participant molecules in the re-modeling phase of bone materials of vertebrates, wherein old bone is dissolved (resorbed) by osteoclast cells (HCl acid and collagenase secreting cells) and new bone becomes deposited (mineralized) by osteoblast cells. The mineralization process results in the deposition of mature (i.e., non-carbonated) or immature (i.e., partially carbonated) hydroxyapatite (HAP), which may involve CO2-carbonation, depending on the function of the perceived bone (e.g., non-dissolvable tooth enamel bone or dissolvable skeletal bone). The present investigation adopted a surface chemical approach to examine impacts of interfacial interactions of wet HCl vapor (at 673 K) and CO2 gas molecules (at 298 K) on the chemical composition and particle morphology of synthetic and biological apatite (AP) materials of varied contents of mature HAP. Studies employing X-ray powder diffractometry, Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray micro-probing were carried out. Accordingly, high relative crystallinity, extent of hydroxylation and Ca/P atomic ratio were found to discern synthetic from biological APs. Furthermore, results obtained helped revealing that (i) compositional (atomic ratios, and extents of hydroxylation and carbonation) and morphological (particle shape and agglomeration) parameters are more diagnostic to the HAP maturity than the geometric structural (crystallization and crystallinity) parameters, (ii) the higher the maturity of the contained HAP, the higher is the resistance of chemical integrity and morphology of the AP material particles to the HCl-acidification, and (iii) a preceding CO2-carbonation lessens HAP-maturity of the AP materials thus rendering them more vulnerable to retrogressive chemical and morphological consequences of the acidification.

Interaction between felsic granitoids and mafic dykes in Bundelkhand Craton: A field, petrographic and crystal size distribution study

In Bundelkhand Craton of central India, mafic dykes intruded when granitoids was partly crystallized. Cuspate–lobate boundary along the contact of granitoids and mafic magma indicates magma mingling in outcrop scale while textural evidence of mingling is represented by acicular apatite morphologies, titanite–plagioclase ocelli and ophitic–subophitic texture, mafic clots, resorbed plagioclase, and hornblende–zircon associations. Mingling also caused thermal exchange and fluid activity along the boundary between two coeval magmas. Crystal size distribution analyses for hornblende in the mafic rocks yield concave up curves which is also consistent with interaction of felsic and mafic magmas.

A Simulated Body Fluid Evaluation of TiO₂ Barrier Oxide Layer Formed by Electrochemical Reaction.

The modified surface during implantation is considered to be an effective strategy to improve high adhesion of bone cell and osseointegration activity. In this paper, the TiO2 barrier oxide Layer has been fabricated by using the ion characteristic of an electrolytic solution, the surface characteristics have been investigated by EDS, XPS, and FE-SEM. From the analysis of the chemical states, phosphorus and calcium were observed in the TiO2 barrier layer, which were penetrated from the electrolyte into the oxide layer during deposit process. In addition, Ca 2p spectrum was identified into two peaks for Ca 2p3/2 and 2p1/2 at 347.4 and 351.3 eV, which are related to hydroxyapatite. Also, P spectrum was confirmed into two peaks for P1/2 and P3/2 levels with binding energy 134.2 and 133.4 eV, respectively. Thus, the incorporated phosphate species were found mostly in the forms of HPO-4, PO-3. From the result of biological evaluation in simulated body fluid (SBF), the apatite morphologies were effective for bioactive property on the modified surface.

Recurrence rates of urinary calculi according to stone composition and morphology.

Few studies have examined the relative risk of recurrence of different stone types. The object of the present study was to evaluate the tendency for stone recurrence as a function of major mineral composition of the stones and morphological characteristics of the stones. This study was carried out using 38,274 stones for which we had data available to specify if the stone was from the first or a subsequent urinary stone episode. Stones were analyzed for morphology by stereomicroscope and for composition by infrared spectroscopy. Overall, 42.7% of stones were from patients who had had a previous stone event, with these being more frequent in men (44.4%) than in women (38.9%, p < 0.0001). Age of first stone occurrence was lowest for dihydroxyadenine (15.7 ± 16.6years) and highest for anhydrous uric acid (62.5 ± 14.9years), with the average age of first stones of calcium oxalate falling in the middle (40.7 ± 14.6years for calcium oxalate dihydrate, and 48.4 ± 15.1years for calcium oxalate monohydrate, COM). By composition alone, COM was among the least recurrent of stones, with only 38.0% of COM stones coming from patients who had had a previous episode; however, when the different morphological types of COM were considered, type Ic-which displays a light color, budding surface and unorganized section-had a significantly greater rate of recurrence, at 82.4% (p < 0.0001), than did other morphologies of COM. Similarly, for stones composed of apatite, morphological type IVa2-a unique form with cracks visible beneath a glossy surface-had a higher rate of recurrence than other apatite morphologies (78.8 vs. 39-42%, p < 0.0001). Stone mineral type alone is insufficient for identifying the potential of recurrence of the stones. Instead, the addition of stone morphology may allow the diagnosis of highly recurrent stones, even among common mineral types (e.g., COM) that in general are less recurrent.

Preparation and Characterization of Precipitated Nano Hydroxyapatite

Calcium Hydroxyapatite [Ca10(PO4)6(OH)2] is the main inorganic constituent of human rigid tissues. It constitentes the major component of bone and enamel. In our present work, hydroxyapatite was synthesized by chemical co- precipitation method with the addition of different concentrations of calcium nitrate tetra hydrate [Ca(NO3)2.4H2O] and phosphoric acid [H3PO4] using micro wave irradiation. Experiments were conducted under controlled environment maintaining required pH, concentration of solution and temperature. The Present report emphasises on the synthesis and characterization of the nano hydroxyapatite. The result of Fourier Transform Infrared Spectroscopy [FTIR] showed the existence of the functional group present in hydroxyapatite. Scanning Electron Microscope [SEM] explains the surface morphology, size and dimensions of hydroxyl apatite. Thermo Gravimetric Analysis and Differential Thermal Analysis [TGA/DTA] analysis confirms that the high thermal stability of hydroxyapatite is due to the variation in concentration and its hardness is maximum.

Melt-derived bioactive glass based on SiO2-CaO-Na2O-P2O5 system fabricated at lower melting temperature

This work addresses the development and fabrication of new bioactive glass composition based on SiO2-CaO-Na2O-P2O5 system that can be melted at lower melting temperature (1377 °C and 1348 °C) than 1400 °C through melt-derived route. All BG compositions did not show significant differences on their particle size while retaining their amorphous structure. Formation of Si-O-Si (tetrahedral) functional group indicated that silicate based glass structure was established as discovered by Fourier transform infrared spectroscope (FTIR). Apatite formation was observed on bioactive glass surface though being fabricated at lower melting temperature upon soaking in Tris-buffer solution. Feature of carbonate (C-O) and P-O functional group was discovered from FTIR for all glass composition. Present of crystalline peaks was detected in X-ray diffraction (XRD) though fewer peaks were observed for glass fabricated at lower melting temperature. Morphology of apatite in crystal cluster form on the glass surface was identified through scanning electron microscope (SEM).

Synthesis and characteristics of sol-gel bioactive SiO2-P2O5-CaO-Ag2O glasses

In this research, the effects of silver additions on the properties of bioactive glass (BG) were investigated. The synthesis of SiO2–CaO–P2O5–Ag2O bioactive glass was performed by the sol-gel route. The synthesized compounds were treated in simulated body fluid (SBF) for 3, 7, and 14days to study the bioactivity of the new glass composition. The obtained samples were evaluated by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma spectroscopy (ICP), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) analyses, MTT assay, and pH meter. Glass specimen with 2mol% of Ag2O exhibited a higher bioactivity when compared with samples containing 4mol% and 6mol% Ag2O. Finally, after 14days, the sample exhibited perfectly dispersed glacier shaped morphology of apatite. This type of morphology has not been previously reported.

Evaluation of bone formation on ultra-fine structures in simulated body fluid

Surface modifications are commonly utilized to adjust the properties of titanium and its alloy surface to the specific needs of medical applications, but there are disadvantages such as poor osteoconductive properties and low adhesion of bone cells to the implant surface. To overcome these limitations, the surface properties affecting osseointegration during implantation must be altered. In this study, we applied a new method for improving surface modifications based on the characteristics of an electrolytic solution.In electrolyte solution containing NaF in Na2SO4, uniform TiO2 nanopores formed and HAp nanoparticles were electrodeposited around the TiO2 nanopores. In the electrolyte solution containing NH4F in (NH4)H2PO4, coarse protrusions, including HAp nanoparticles, were regularly deposited onto the TiO2 barrier layer. The surface characteristics and distributed elements were investigated by energy-dispersive X-ray spectroscopy analysis, while analysis of the ultra-fine structure of the surface was carried out by field emission scanning electron microscopy. To investigate the behavior of the anion, chemical states were analyzed by X-ray photoelectron spectroscopy. The narrow spectra for Ti 2P, Ca 2p, and P 2p were similar and depended on the characteristics of the electrolyte solution. In addition, the Ca 2p spectrum showed two peaks for Ca 2p3/2 and 2p1/2 at 347.4 and 351.3 eV, respectively, which may be related to hydroxyapatite. Additionally, the P peak was deconvoluted into two peaks for P1/2 and P3/2 levels with binding energies of 134.2 and 133.4 eV, respectively. A soaking test showed that apatite morphologies were well-formed onto the modified surface at different times.