Hydroxyapatite Formation Ability Research Articles

Neodymium (III)-containing poly(lactide-co-glycolide)-coated robocast bioactive glass scaffolds for photothermal therapy and bone regeneration

In this study, trivalent neodymium-doped silicate-based 13–93 bioactive glass scaffolds were prepared by the robocasting method using sol-gel-derived bioactive glass powders for tissue engineering applications. Sintered scaffolds were coated by borate-based 13-93B3 bioactive glass-containing polylactide-co-glycolide solution. The produced composite scaffolds’ mechanical, morphological, and structural characteristics were thoroughly examined, as their in vitro bioactivity in cell culture media and simulated body fluid. Furthermore, the scaffolds’ amoxicillin adsorption and release behavior was examined over time. The outcomes demonstrated that it was feasible to effectively create periodic, mesh-like-patterned robocast glass scaffolds utilizing Nd3+-doped sol-gel-derived bioactive glass powders. The scaffolds’ compressive strengths ranged from 10.02 MPa to 18.6 MPa, with the PLGA-coated scaffolds exhibiting the highest strength values. All of the scaffolds that were submerged in simulated body fluid for 28 days showed hydroxyapatite formation. The presence of borate glass on the surface of the silicate-based glass scaffolds improved the hydroxyapatite formation ability. The quantity of drug adsorption for all types of scaffolds was measured to be between 4 and 9% whereas the cumulative drug release was in the range of 58 to 96%. Borate glass particle-containing PLGA coating enhanced the drug delivery behavior.

Preparation of Titanium–Calcium Alloy Films and Evaluation of Hydroxyapatite Formation Ability

Preparation of Titanium–Calcium Alloy Films and Evaluation of Hydroxyapatite Formation Ability

Improvement of hydroxyapatite formation ability of titanium-based alloys by combination of acid etching and apatite nuclei precipitation.

The authors aimed to improve hydroxyapatite formation ability of Ti6Al4V, Ti-15Mo-5Zr-3Al alloy, Ti-12Ta-9Nb-6Zr-3V-O alloy (Gummetal®) and commercially pure Ti (cpTi) mesh by a combination of acid etching and apatite nuclei precipitation. Surfaces of specimens were etched with H2SO4 for pores formation on the specimens. Thus-etched specimens were soaked in an alkalinised simulated body fluid (SBF), which was adjusted at higher pH than that of conventional SBF and this solution was subsequently heated. By this treatment, apatite nuclei were precipitated in the pores of the specimens. By a soak in the conventional SBF to check hydroxyapatite formation ability, hydroxyapatite was covered the entire surfaces of the specimens within 1 day and high hydroxyapatite formation ability was successfully shown. The adhesion strength of the hydroxyapatite film formed in the above SBF test showed larger value as increasing the surface roughness of the specimens by adjusting the above acid etching condition depending on the kinds of Ti-based alloys. This is because the adhesion of the hydroxyapatite film occurred by the mechanical interlocking effect. In addition, this method showed shape selectivity of the materials because similar hydroxyapatite formation ability could be introduced to the cpTi mesh.

Impartation of hydroxyapatite formation ability to ultra-high molecular weight polyethylene by deposition of apatite nuclei.

The authors aimed to impart hydroxyapatite formation ability to ultra-high molecular weight polyethylene (UHMWPE) by deposition of apatite nuclei (ApN) by the following two methods. The first method was electrophoretic deposition (EPD). A porous UHMWPE was placed between electrodes in the ApN-dispersed ethanol and constant voltage was applied. By this treatment, the ApN were migrated from anode-side surface to the cathode one through the pores by an electric field in the pores of the UHMWPE and deposited inside the pores. The second method was direct precipitation (DP) of the ApN. A porous UHMWPE was soaked in a simulated body fluid (1.0SBF) with higher pH than the physiological one and subsequently, its temperature was raised. By this treatment, the ApN were precipitated in the pores of the UHMWPE directly in the reaction solution. For both methods, the ApN-deposited UHMWPE showed HAp formation ability not only on the top surface but also inside the pores near the surface of the porous UHMWPE in 1.0SBF although the adhesion strength of thus-formed HAp layer was higher in the case of the EPD in comparison with the DP, oxygen plasma treatment before the DP enabled to achieve a similar level of the HAp layer adhesion to the EPD.

Design and evaluation a kind of functional biomaterial for bone tissue engineering: Selenium/mesoporous bioactive glass nanospheres

Conventional treatments of bone tumor involve removal followed by radiation and chemotherapeutic drugs that may have limitations and cause secondary damage. The development of functional filling biomaterial has led to a new strategy for tumor therapy. In this study, a novel therapeutic ion selenium doped mesoporous bioactive glasses (Se/MBG) nanospheres were successfully synthesized by a facile sol–gel technique using cetyl trimethyl ammonium bromide (CTAB) as the template, which had uniform spherical morphology (≈ 400 nm), high surface area (>400 m2/g) and mesopore volume (≈0.30 cm3/g). Results showed that hydroxyapatite formation ability and controllable doxorubicin (DOX) release and distinct degradation of Se/MBG nanospheres depended on the dose of Se4+. In vitro cell cultures showed that both Se/MBG and DOX-Se/MBG nanospheres had the culture time and dose dependent cytotoxicity to MG63 osteosarcoma cells. But DOX-Se/MBG nanospheres reduced the acute cytotoxicity to MG63 because of the co-operative effect of Se and DOX. Meanwhile, Se/MBG nanospheres were found to have selective cytotoxicity to cancer cells (MG63) and normal cells (MC3T3-E1), indicating that the prepared Se/MBG nanospheres had cell recognition function. These all note that the synthesized Se/MBG nanospheres can be used as a filling biomaterial for the bone tissue engineering.

Preliminary studies of the effect of doping of chromium oxide in SiO2-CaO-P2O5 bioceramics for bone regeneration applications.

Bioceramics of composition xCr2O3∙(43-x) CaO∙42SiO2∙15P2O5 (x varying from 0 to 8 mol%) have been synthesized in the laboratory by using sol-gel technique. The morphology and structure has been determined by using Powder X-ray Diffraction, Fourier Transform Infrared and Raman spectroscopy and Field Emission Scanning Electron Microscopy. The in vitro bio mineralization behavior has been assessed by immersion in simulated body fluid for 7 days. The results obtained in our studies have indicated excellent hydroxyapatite formation ability of our samples. Drug delivery property of synthesized samples has been checked by using UV-spectroscopy of antibiotic 'gentamicin'. The in vitro drug release profile was fitted best in the Higuchi model with the highest value of coefficient of determination (R2 = 0.9970). Antimicrobial properties have been evaluated from minimum inhibitory concentration and time kill assay values. The cellular response has been investigated by using human osteosarcoma MG 63 cell line. Also to check charge on the synthesized samples, Zeta potential studies have been conducted and it has been observed that samples carry negative charge when immersed in simulated body fluid. Negative surface charge provide suitable environment for cell adhesion and proliferation. Experiments have been undertaken to explore suitable composition with an objective of development of suitable implant material for bone regeneration applications.

Development of Bioactive Apatite Nuclei-Precipitated Ti-12Ta-9Nb-6Zr-3V-O Alloy

Ti-12Ta-9Nb-6Zr-3V-O alloy, one of the shape-memory alloys with lower Young’s modulus in comparison with conventional titanium alloy, was treated with sulfuric acid to form roughened surface on the substrate. In order to impart hydroxyapatite formation ability to the Ti-12Ta-9Nb-6Zr-3V-O alloy, apatite nuclei (AN) were precipitated on the roughened surface using simulated body fluid (SBF) adjusted at higher pH than physiological condition. By this treatment, AN-precipitated Ti-12Ta-9Nb-6Zr-3V-O alloy was obtained. The AN-precipitated Ti-12Ta-9Nb-6Zr-3V-O alloy showed high hydroxyapatite formation ability in physiological SBF.

A comparative study of physico-mechanical, bioactivity and hemolysis properties of pseudo-wollastonite and wollastonite glass-ceramic synthesized from solid wastes

This study aims to synthesize pseudo-wollastonite and wollastonite base glass-ceramic from solid wastes, and a comparative study of their physico-mechanical, bioactivity, and hemolysis properties is conducted. The stoichiometric amount of chicken eggshells derived CaO (~99%), and rice husk ash (RHA) derived nano SiO2 (~99%) is used as ingredients for the formulation of wollastonite. The pseudo-wollastonite (α-W) is synthesized by sintering the ingredients at 1200 °C for 4 h, and wollastonite glass is made through the quenching method after melting of the ingredients at 1400 °C. The wollastonite glass-ceramic (GC) is prepared by control heat-treatment of wollastonite glass at 1200 °C for 1 h. Numerous characterizations like X-ray diffraction (XRD), scanning electron microscopy (SEM), apparent porosity and bending strength of α-W and GC are comparatively investigated. The GC is composed of the collaborative pseudo-wollastonite nucleation (~35%) and amorphous phases. α-W and GC show the apparent porosity about 4.23 % and 2.77 %, bending strength about 108 MPa and 139 MPa, and an average grain size about 2.30 μm and 0.60 μm, respectively. The obtained results exhibit that the waste-derived both α-W and GC have excellent bioactivity and good hemolysis index (<2%). Moreover, GC shows slightly more hydroxyapatite (HA) layer formation ability than α-W in the simulated body fluid (SBF) solution. This comparative study of α-W and GC is recommended that the GC is offering more promising characteristics for biomedical applications.

Characterization and Investigation of Biological Properties of Ag-Doped TiO2 Coatings Fabricated on Titanium

In present study, Ag-doped TiO 2 bioceramic coatings were fabricated on cp-Ti by plasma electrolytic oxidation (PEO) and physical vapor deposition (PVD). The phase composition, surface microstructure, elemental composition, surface topography, wettability and chemical state of the PEO and Ag-doped TiO 2 surfaces were characterized by using powder- and thin film-X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface profilometer and contact angle measurement system (CAM), respectively. The PEO coating’ surface was porous and rough due to the nature of process. The Ti, anatase-TiO 2 , rutile-TiO 2 and Ag 2 O phases were detected on the Ag-doped PEO surfaces by TF-XRD while The Ti, anatase and rutile phases were obtained on the PEO surfaces. The surface morphology structure of the PEO coating was not changed by PVD process. The Ti, O, P and Ag elements were observed on the Ag-doped PEO surfaces by EDS. Also, the amount of Ag existed on the surface was below cytotoxic limit. The Ag-doped PEO surfaces indicated better hydrophilic character to the PEO surface owing to increasing polarity of the surfaces. In vitro hydroxyapatite-forming ability was evaluated by immersion in simulated body fluid (SBF) at 36.5 ° C for 28 days. The Ag-doped PEO surfaces showed good hydroxyapatite formation ability compared to the PEO surface. The antibacterial activity was evaluated by exposing the samples to Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ) and they were compared by the reaction of the pathogens to Ag-doped PEO with the PEO controls. The antibacterial ability of the Ag-doped PEO surfaces was significantly improved respect to the PEO surfaces for S. aureus and E. coli .

Preparation of a novel bone wax with modified tricalcium silicate cement and BGs

Amino-grafted and vaterite-contained tricalcium silicate cement (A-V-C3S) was composited with 58S bioglass/chitosan/carboxy methyl cellulose (BG/CS/CMC, referred as BGs) to surmount the non-absorbability and infection problems of traditional bone wax. Its material, bioactive, biocompatible and antibacterial properties were systematically characterized. The results revealed that A-V-C3S/BGs possessed self-setting, injectable, mechanical and degradable abilities. A-V-C3S/BGs (1:1 g/g) was optimum owing to its higher compressive strength (9.91 MPa) and lower pH value (7.6 to 8.1) in the test groups. In vitro immersion experiment demonstrated that A-V-C3S/BGs had good hydroxyapatite formation ability, and its excellent cell adhesion, low cytotoxicity and superior cell proliferation were verified by mouse embryonic osteoblast precursor cells in cell tests. Compared with A-V-C3S, antibacterial experiment illustrated the significantly enhanced antibacterial property of A-V-C3S/BGs to Staphylococcus aureus and Escherichia coli.

Effect of different chemical treatments on hydroxyapatite formation of carbon fibers reinforced carbon and SiC dual matrices composites

In this study, the carbon fibers reinforced carbon and SiC dual matrices (C/C-SiC) composites with 3D needle-punched structure were fabricated by liquid silicon infiltration (LSI). This work focused on the effects of different chemical treatments (aqueous of HF/HNO3, aqua regia and CaCl2 solution) on apatite formation under biomimetic condition. Samples were characterized by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR) and so on. The ability of hydroxyapatite formation was evaluated by simulated body fluid (SBF) immersion test. The formation mechanism of apatite layer grown on modified C/C-SiC composites was also revealed. The results showed that modified sample surfaces were consisted of groups OH, COOH or/and Ca2+ ions. These negatively functional groups attracted surrounding Ca2+ ions to form and anchor the nucleus. The Ca2+ ions contributed to the apatite nucleation and proliferation by increasing apatite saturation. The SBF results showed that a homogeneous precipitation layer of apatite formed on C/C-SiC after about two weeks under the combined actions of aqua regia and CaCl2. This suggested treatments of aqua regia and CaCl2 solution led to positive results in terms of apatite formation of modified C/C-SiC compared to the native C/C-SiC material.

Novel bone wax based on tricalcium silicate cement and BGs mixtures

Classic bone wax is effectively hemostatic and low-cost, but it has shortcomings like infection and nonabsorbability. A novel self-curing bone wax was developed by mixing tricalcium silicate (C3S) cement and 58S bioactive glass/chitosan/carboxy methyl cellulose (BG/CS/CMC, referred to as BGs) to overcome these problems. It was found that the addition of BGs improved anti-washout and operational properties of C3S, and C3S had good self-curing and mechanical behavior. C3S/BGs with a mass ratio of 2:1 possessed better material performance in the setting time, mechanical strength, and injection property in the test group. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) confirmed the hydroxyapatite (HAp) formation ability of C3S/BGs. The cell compatibility was investigated in vitro by culturing mouse embryonic osteoblast precursor cells (MC3T3-E1) in the extract of C3S/BGs. The results showed that the bone wax compound presented low cytotoxicity and good cell proliferation.

Preparation and characterization of PCL-coated porous hydroxyapatite scaffolds in the presence of MWCNTs and graphene for orthopedic applications

Macro-channeled porous hydroxyapatite (HA) scaffolds were fabricated by a polymer foam replication method. Composites were prepared by coating the surface of HA scaffolds with polycaprolactone (PCL) in the presence of graphene nanopowders (in the form of flakes) and multi-walled carbon nanotubes (MWCNTs) at different concentrations. Compression strength of the scaffolds was investigated as a function of additive concentration. Results revealed that the use of PCL coating increased the mechanical strength of HA scaffolds. Besides, addition of graphene or MWCNTs further improved the compression strength of the constructs when they were used at 0.25 wt% and a decrease was observed at higher graphene and MWCNT concentrations. Highest mechanical performance was obtained in composite HA scaffolds involving MWCNTs. In vitro acellular bioactivity experiments revealed that both graphene and MWCNT-incorporated HA scaffolds showed higher bioactivity in simulated body fluid compared to bare scaffolds. However, HA formation ability was more pronounced with MWCNTs compared to graphene nanoflakes where they were possibly acted as an effective nucleation sites to induce the formation of a biomimetic apatite. Additionally, scaffolds prepared in the study were found to be nontoxic to the mouse bone marrow mesenchymal stem cells.

Control of surface potential and hydroxyapatite formation on TiO2 scales containing nitrogen-related defects

The hydroxyapatite (HAp) formation ability and related surface potentials of rutile-type TiO2 scales formed on Ti are controlled by varying the Ti heat treatment conditions in a N2 atmosphere containing a trace amount of O2. The zeta potentials of the samples heated at 873 and 973 K for 1 h are large negative and positive values, respectively, where HAp formation on the surface is enhanced in both cases. Upon longer heat treatment at those temperatures, the HAp forming ability diminishes and the zeta potential becomes more neutral. Kelvin probe force microscopy indicates that, under dry conditions, the surface charges on the TiO2 scales formed at 873 and 973 K in 1 h are positive and negative, respectively, opposite to the signs of the zeta potentials measured under wet conditions. Scanning transmission electron microscopy, electron energy loss spectroscopy, and calculations of defect formation energies reveal that nitrogen atoms incorporated into TiO2 during scale formation produce the charged defects (NO)O−1 and (N2)O+2 for the scales formed in 1 h at 873 and 973 K, respectively. In the case of longer treatments, nitrogen-related defects presumably transform into more stable states, such as N2 gas, in voids, resulting in a neutral surface. The present findings lead to physical models of surface charge distributions that elucidate the relationship between nitrogen-related defects, charged surfaces, and HAp formation mechanisms.

Bioactive pedicle screws prepared by chemical and heat treatments improved biocompatibility and bone-bonding ability in canine lumbar spines.

BackgroundTitanium (Ti)-6Al-4V alloy, which is widely used in spinal instrumentation with a pedicle screw (PS) system. However, significant clinical problems, including loosening and back-out of PSs, persist. During the last decade, a novel technology that produces bioactive Ti from chemical and heat treatments has been reported that induces the spontaneous formation of a hydroxyapatite (HA) layer on the surface of Ti materials. The purpose of this study was to study the effect of bioactivation of Ti-6Al-4V PSs on the ability of HA formation in vitro and its biocompatibility and bone-bonding ability in vivo.MethodsTi-6V-4Al alloy PSs were prepared and bioactivated by NaOH-CaCl2-heat-water treatments. The HA-forming ability of bioactive PSs in simulated body fluid (SBF) was evaluated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). Six 11-month-old female beagle dogs were used for the in vivo study. Bioactive and control (without bioactivation) PSs were left and right randomly placed from L1 to L6. One and three months after surgery, lumbar spines were removed for biomechanical and histological analyses.ResultsIn vitro: The surface analysis of bioactive PSs by FE-SEM and EDX showed substantial HA deposits over the entire surface. In vivo: The mean extraction torque was significantly higher for bioactive PSs compared to controls PSs (P<0.01); there was no significant difference in pull-out strength between control and bioactive PSs. Histologically, the contact area between bone tissue and screw surface showed no significant trend to be greater in bioactive PSs compared to control PSs (P = 0.06).ConclusionsBioactive PSs prepared by chemical and heat treatments formed layers of HA on the surface of screws in vitro that improved biocompatibility and bonding ability with bone in vivo. Bioactive PSs may reduce screw loosening to overcome the obstacles confronted in spinal instrumentation surgery.

Metallurgical properties and biomimetic HA deposition performance of Ti-Nb PIM alloys

Ti-Nb alloys are potential candidates owing to their excellent mechanical properties and high corrosion resistance for bioactive implant applications compared to other metallic materials. The purpose of this work is to investigate the effect of the Nb amount on the microstructure, mechanical properties, corrosion behavior and hydroxyapatite (HA) formation ability of Ti-Nb alloys produced via powder injection molding. According to the phase/microstructure studies, including XRD analyses, optical microscope, and SEM imaging, all of the alloys are composed of α+β phases, and with the increment of Nb content, β phase stability increases. Also, it is observed that Nb content has significant effects on the mechanical properties of the considered alloys. While the hardness/Transverse rupture strength values of Ti-Nb alloys (303-340HV, 992-440 MPa) are higher than that of the titanium (269HV, 300 MPa), the elastic modulus is measured as lower than (100–115 GPa) that of the titanium (132–140 GPa). The increment of Nb content causes to decrease of the hardness, bending strength and elastic modulus of Ti-Nb alloys. Also, the addition of Nb contributed to the improvement of corrosion resistance and induced to increase of hydroxyapatite formation ability.

Sol-gel derived terbium-containing mesoporous bioactive glasses nanospheres: In vitro hydroxyapatite formation and drug delivery

Terbium (Tb) doped mesoporous bioactive glasses (Tb/MBG) nanospheres were successfully synthesized by a facile sol-gel method using cetyl trimethyl ammonium bromide (CTAB) as the template. Results indicated that Tb/MBG had spherical morphology (100–200nm), higher specific surface area (250–350m2/g) and narrow mesopore size distribution (2–3nm). In order to investigate the effects of Tb on the in vitro bioactivity, prepared Tb/MBG nanospheres were soaking in simulated body fluid (SBF) for 3 days, and results indicated incorporation Tb ions in the MBG nanospheres could improve the hydroxyapatite formation ability. In addition, Tb/MBG nanospheres showed controlled release property of anti-cancer drugs (DOX) and distinct degradation in PBS with different pH values. Their release mechanism can be explained by Fickian diffusion according the Higuchi model, and the delivery of DOX from Tb/MBG nanospheres can be dominated by changing the doping concentration of Tb and the values of pH. In addition, the cytotoxicity of Tb/MBG nanospheres was assessed using a cell counting kit-8 (CCK-8), and results showed that the synthesized Tb/MBG nanospheres at low concentration had no significant cytotoxicity in MC3T3 cells. These all note that this material is a promising candidate for the therapy of bone tissue regeneration.

Effect of pores formation process and oxygen plasma treatment to hydroxyapatite formation on bioactive PEEK prepared by incorporation of precursor of apatite

When bioinert substrates with fine-sized pores are immersed in a simulated body fluid (SBF) and the pH value or the temperature is increased, fine particles of calcium phosphate, which the authors denoted as ‘precursor of apatite’ (PrA), are formed in the pores. By this method, hydroxyapatite formation ability can be provided to various kinds of bioinert materials. In this study, the authors studied fabrication methods of bioactive PEEK by using the above-mentioned process. First, the fine-sized pores were formed on the surface of the PEEK substrate by H2SO4 treatment. Next, to provide hydrophilic property to the PEEK, the surfaces of the PEEK were treated with O2 plasma. Finally, PrA were formed in the pores by the above-mentioned process, which is denoted as ‘Alkaline SBF’ treatment, and the bioactive PEEK was obtained. By immersing in SBF with the physiological condition, hydroxyapatite formation was induced on the whole surface of the substrate within 1day. The formation of PrA directly contributed to hydroxyapatite formation ability. By applying the O2 plasma treatment, hydroxyapatite formation was uniformly performed on the whole surface of the substrate. The H2SO4 treatment contributed to a considerable enhancement of adhesive strength of the formed hydroxyapatite layer formed in SBF because of the increase of surface areas of the substrate. As a comparative study, the sandblasting method was applied as the pores formation process instead of the H2SO4 treatment. Although hydroxyapatite formation was provided also in this case, however, the adhesion of the formed hydroxyapatite layer to the substrate was not sufficient even if the O2 plasma treatment was conducted. This result indicates that the fine-sized pores should be formed on the whole surface of the substrate uniformly to achieve high adhesive strength of the hydroxyapatite layer. Therefore, it is considered that the H2SO4 treatment before the O2 plasma and the ‘Alkaline SBF’ treatment is an important factor to achieve high adhesive strength of hydroxyapatite layer to the PEEK substrate. This material is expected to be a candidate for next-generation implant materials with high bioactivity.

Fabrication of MTA-like cements and their mechanical, handling, and setting properties in relation to the choice of setting solution

Mineral trioxide aggregate (MTA) has been used as root-end filling material in dentistry due to its excellent sealing ability as well as biocompatibility. However, some drawbacks of MTA cements, including low cohesive property and long setting time, have limited their widespread applications. In this research, we evaluated the effect of three setting solutions, namely distilled water, malic acid, and chitosan solution on the mechanical, handling, and setting properties of the cements. The chitosan-containing cements showed superior setting time and handling properties over the water- and malic-acid-containing cements. The mechanical strength of water- and chitosan-containing cements was almost similar but significantly improved as compared to malic-acid-containing cements. Our results from morphology and chemical analysis showed that the chitosan-containing MTA cements improved the hydroxyapatite-formation ability as compared to those which were made by water and malic acid. It was concluded that the chitosan-containing MTA cements have an excellent potential to be acceptable as root-end filling materials.

Development of bioceramic bone scaffolds by introducing triple liquid phases

Abstract