Fluorohydroxyapatite Research Articles

In vitro corrosion and cytocompatibility of Mg-Zn-Ca alloys coated with FHA

In the field of orthopedics, it’s crucial to effectively slow down the degradation rate of Mg alloys. This study aims to improve the degradation behavior of Mg-Zn-Ca alloys by electrodepositing fluorohydroxyapatite (FHA). We investigated the microstructure and bond strength of the deposition, as well as degradation and cellular reactions. After 15–30 days of degradation in Hanks solution, FHA deposited alloys showed enhanced stability and less pH change. The strong interfacial bond between FHA and the Mg-Zn-Ca substrate was verified through scratch tests (Critical loads: 10.73 ± 0.014 N in Mg-Zn-0.5Ca alloys). Cellular studies demonstrated that FHA-coated alloys exhibited good cytocompatibility and promoted the growth of MC3T3-E1 cells. Further tests showed FHA-coated alloys owed improved early bone mineralization and osteogenic properties, especially in Mg-Zn-0.5Ca. This research highlighted the potential of FHA-coated Mg-Zn-0.5Ca alloys in orthopedics applications.

Surface modification of AZ31 Mg alloy by diopside/fluorohydroxyapatite/graphene oxide nanocomposite coating: Corrosion and bioactivity evaluations

There is a high research demand to enhance magnesium-based orthopedic implants' biocompatibility and corrosion resistance. This work reports the development of a nanocomposite ceramic coating based on diopside (Dio) / fluorohydroxyapatite (FHA) / graphene oxide (GO) via the electrophoretic deposition (EPD) method on the AZ31 Mg alloy substrate. FESEM, EDS, XRD, and FTIR were employed to characterize the physicochemical properties of the synthesized diopside and fluorohydroxyapatite ceramic nanoparticles and the EPD ceramic films. The introduction of GO in the Dio/FHA composite film eliminated pores and cracks, improved coating quality, and reduced the film thickness. AFM confirmed a decrease in surface roughness from 184.6 nm to 171.8 nm and wettability enhanced by contact angle reduction from 52.1° to 38.3°. Electrochemical polarization and EIS analyses indicated an 83% boost in corrosion resistance and a 52% reduction in corrosion current density in Dio/FHA/GO vs. Dio/FHA sample. Bioactivity evaluation after five days of immersion in simulated body fluid (SBF) was suggestive that the synergistic effect of Dio, FHA, and GO caused the most abundant apatite formation in Dio/FHA/GO film. The antibacterial activity findings showed that the Dio/FHA/GO coating could function as an antibacterial nanocomposite coating against S. Aureus and E. Coli. Overall, the Dio/FHA/GO EPD film is a highly potential ceramic biomedical coating to improve the corrosion resistance, surface properties, bioactivity, and antibacterial behavior of Mg alloys.

Effect of Fluorohydroxyapatite on Biological and Physical Properties of MTA Angelus.

This study aimed to assess the effect of addition of fluorohydroxyapatite (FHI) on biological and physical properties of mineral trioxide aggregate (MTA) Angelus. In this in vitro, experimental study, nano-FHI powder was first synthesized, and the morphology and chemical structure of particles were evaluated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Three groups were evaluated in this study: MTA Angelus, MTA modified with 10% FHA, and MTA modified with 15% FHA. After mixing, the materials were applied to ring molds (10 mm diameter, 1 mm height), and the setting time of the three groups was evaluated according to ISO6876 and ASTMC266-03 with a Gillmore needle. The pH was measured using a pH meter at 24 and 48 hours and 7 days after mixing. The cytotoxicity of the materials was assessed in freshly mixed form and after 1 and 7 days using the methyl thiazolyl tetrazolium (MTT) assay according to ISO10993-5. Data were analyzed by one-way and repeated measures ANOVA and Tukey's test (alpha = 0.05). The addition of FHA to MTA significantly decreased the initial setting time (P < 0.05) and had no significant effect on cell viability (compared with pure MTA Angelus) at 1 and 7 days. However, modified MTA groups in freshly mixed form showed significantly lower cell viability (P < 0.05). The pH remained alkaline at all time points. Addition of 15% FHA to MTA Angelus decreased its setting time with no adverse effect on cell viability (except for fresh form) or pH.

Corrosion resistance studies of copper and magnesium-doped fluorohydroxyapatite coatings on titanium biomaterial

This study discusses the contribution of Cu2+ and Mg2+, two biologically important ions substituted into the structure of fluorohydroxyapatite. FHA, a partial substitution of fluorine ion in HA has received a great attention because it improves the corrosion resistance of orthopedic implants. Copper, Magnesium and copper-Magnesium doped fluorohydroxyapatite (FHA) coatings were electrochemical deposited on titanium (Ti) using a cyclic voltammetry technique. The coatings properties were identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The corrosion behavior of coated and uncoated samples, immersed for 7 days in aerated simulated body fluid (SBF) in a presence of 0.2 g/l human serum albumin (HAS) was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The synergetic effect of albumin and doped elements on the degradation of Ti was studied. As a result of these investigations, it is revealed that: fluoride, copper and magnesium were successfully incorporated into apatite lattice structure. The additions of ions in FHA crystal matrix reduced the crystallite size, increased the crystallinity and changed the structure of F-hydroxyapatite. All the electrochemical techniques employed demonstrated that the coatings that were produced offered superior protection against corrosion for titanium when exposed to artificial body fluids. The nano-Mg-FHA coating improves effective protection to Ti and presents the highest corrosion resistance. The outcomes of this investigation were also compared with already published works to validate the research results.

Long-Term Outcomes of Implants Placed in Maxillary Sinus Floor Augmentation with Porous Fluorohydroxyapatite (Algipore® FRIOS®) in Comparison with Anorganic Bovine Bone (Bio-Oss®) and Platelet Rich Plasma (PRP): A Retrospective Study.

Purpose: The objective of this retrospective study was to evaluate the long-term clinical outcomes of bone regeneration procedures using algae-derived plant hydroxyapatite (Algipore® FRIOS®) compared with demineralized anorganic bovine bone (Bio-Oss®), in combination with autologous blood-derived PRP. Materials and Methods: Partially edentulous patients with severe atrophy of posterior maxillary treated by means of the split bone technique in a two-stage grafting procedures were observed for up to seven years after implants placement. After surgeries, the natural porous fluorohydroxyapatite (FHA) (Algipore® FRIOS®; Group, n = 29) or anorganic bovine bone (Bio-Oss® Group, n = 28) with autogenous bone in a 50:50 composite ratio with PRP, were administered in a 2.8-mm critical-size defect (CSD). Four months later, implants were placed at second-stage surgery. Results: A sample of fifty-seven consecutive patients who required sinus augmentation was included in the study, and 57 implants were placed. There was no drop out or loss of follow-up of any case. Clinical and radiographic examinations revealed a comparable pattern of newly formed bone in both groups after seven years of functional loading for implants placed after sinus augmentation using porous fluorohydroxyapatite and anorganic bovine bone. No significant difference in marginal bone loss was found around implants in both groups. Conclusions: The favorable implant outcomes suggest both biomaterials are suitable for sinus grafting in severely atrophic maxillae.

Effect of topically applied silver compounds on the demineralisation of hydroxyapatite

ObjectivesThis study investigates the demineralization inhibitory mechanisms of AgNO3, AgF and silver diamine fluoride (SDF) using a previously used hydroxyapatite (HAP) caries demineralization model system. MethodsHAP discs were allocated into three groups (n = 3) and immersed in demineralization solution (buffered pH 4.0, 0.1 mol/L acetic acid) for 4 h. Each disc was treated topically with either 3.16 M AgNO3, 3.16 M AgF or 3.16 M SDF using a micro-brush. The discs were then demineralized for a further 4 h. Calcium, silver, and fluoride ion selective electrodes (ISEs) were used to monitor the changes in each ion concentration at 1 min intervals throughout. Demineralization inhibition was calculated as the percentage reduction in the rate of calcium ion loss from HAP (PRCLHAP). Characterization of similarly treated HAP powder was carried out with Magic Angle Spinning-Nuclear Magnetic Resonance ResultsThe mean PRCLHAP for each treatment group was; AgF (72.3 + 4.8%), SDF (69.7 + 5.3%) and AgNO3 (14.9 + 2.7%). Ag3PO4 was detected in all HAP powders. CaF2 and fluorohydroxyapatite (FHA) were detected only in powders treated with either AgF or SDF.The demineralization inhibitory efficacy of topically applied AgNO3 results from the formation of a Ag3PO4 barrier. Whereas, the demineralization inhibitory efficacy of topically applied AgF, and SDF, results from the formation of a barrier composed of Ag3PO4, CaF2, and FHA. SignificanceIn addition to their anti-microbial properties, clinical topical application of silver compounds for caries preventative treatment is due to their ability to form acid-resistant barriers composed of silver phosphate. When fluoride is present, this barrier also contains CaF2 and FHA, additionally protecting the mineral.

Fluorapatite and fluorohydroxyapatite apatite surfaces drive adipose-derived stem cells to an osteogenic lineage

PurposeHydroxyapatite (HA) scaffolds are common replacement materials used in the clinical management of critical-sized bone defects. This study was undertaken to examine the potential benefits of fluoridated derivatives of hydroxyapatite, fluorapatite (FA), and fluorohydroxyapatite (FHA) as bone scaffolds in conjunction with adipose-derived stem cells (ADSCs). If FHA and FA surfaces could drive the differentiation of stem cells to an osteogenic phenotype, the combination of these ceramic scaffolds with ADSCs could produce materials with mechanical strength and remodeling potential comparable to autologous bone. This study was designed to investigate the ability of the apatite surfaces HA, FA, and FHA produced at different sintering temperatures to drive ADSCs toward osteogenic lineages. Methods: HA, FHA, and FA surfaces sintered at 1150 °C and 1250 °C were seeded with ADSCs and evaluated for cell growth and gene and protein expression of osteogenic markers at 2 and 10 days post-seeding. Results: In vitro, ADSC cells were viable on all surfaces; however, differentiation of these cells into osteoblastic lineage only observed in apatite surfaces. ADSCs seeded on FA and FHA expressed genes and proteins related to osteogenic differentiation markers to a greater extent by Day 2 when compared to HA and cell culture controls. By day 10, HA, FA, and FHA all expressed more bone differentiation markers compared to cell culture controls. Conclusion: FA and FHA apatite scaffolds may promote the differentiation of ADSCs at an earlier time point than HA surfaces. Combining apatite scaffolds with ADSCs has the potential to improve bone regeneration following bone injury.

A modified TEGDMA-based resin infiltrant using polyurethane acrylate oligomer and remineralising nano-fillers with improved physical properties and remineralisation potential

ObjectivesThis study aimed to modify an experimental triethylene glycol dimethacrylate (TEGDMA) based resin infiltrant using PUA oligomer and two remineralising fillers, including fluorohydroxyapatite (FHA) and fluoride-doped bioactive glass (FD-BG), to improve the mechanical and physical properties and induce remineralising potential. Materials and methodsThe polyurethane acrylate oligomer (PUA) was synthesised and characterised. Experimental resin infiltrant was prepared by mixing 10% of synthesised PUA with 88% TEGDMA. Water contact angle, penetration coefficient, and penetration depth were then measured. The FHA and FD-BG fillers were synthesised and characterised. To prepare nano-filled resin infiltrant, 5% of each powder was mixed with the prepared resin infiltrant. The prepared resin infiltrants were characterised to evaluate their degree of conversion, mechanical properties, water sorption, and solubility. The ion release of filled resin was also assessed. The non-infiltrated and infiltrated enamel specimens underwent fourteen days of pH-cycling, and a surface microhardness was done to assess the resistance to demineralisation. ResultsThe results showed that the addition of PUA to TEGDMA increased the mechanical properties and decreased water sorption and solubility. The addition of synthesised FD-BG fillers to resin infiltrant significantly improved the resistance to demineralisation of enamel samples compared with other groups (p ≤ 0.001). The FHA fillers also improved the resistance to demineralisation; however, the produced changes were not statistically meaningful (p > 0.05). ConclusionsBased on the results, the PUA+TEGDMA+ FD-BG/FHA composite can be used as an alternative material for pure TEGDMA in enamel infiltration approaches owing to its better mechanical properties, lower water sorption and solubility, and also remineralisation potential. Clinical SignificanceA resin infiltrant with remineralisation potential, lower water sorption and solubility and higher mechanical properties may enhance the management of early caries lesions.

A multilayer biomimetic chitosan-gelatin-fluorohydroxyapatite cartilage scaffold using for regenerative medicine application

In the present study, pure chitosan and gelatin solutions are blended at four various ratios with the addition of Fluorohydroxyapatite (FHA). The specimens are fed into the Freeze-Drying (FD) apparatus to produce porous architectures. The X-ray Diffraction (XRD) and the Scanning Electron Microscopy (SEM) are used for analyzing the solutions and finding the best solution regarding the number of beads and droplets, yielded fibers, and morphological uniformity. The flow rate, voltage, and distance from the needle to the collector are variate in the selected specimen for examining the impact processing parameters on fibers morphology and nanofibers diameter. The in-vitro biocompatibility examination is executed with human skin fibroblasts to distinguish the cell proliferation level on the scaffolds. The results obtained by XRD and SEM confirmed that the specimen containing 70% and 30% chitosan and gelatin, respectively, includes the minimum number of beads, droplets, yielded fibers, and the maximum morphological uniformity. Then, the in-vitro biocompatibility tests confirmed high and acceptable biological properties for the specimen. For more details, the experimental tests report that S1 has the maximum displacement value of 207.64 nm, while S4 represents the lowest displacement value of 175.87 nm. Moreover, the numerical study indicated that the scaffold compressive strength increases from 22.8 MPa (S1) to 31.2 MPa (S4) with the addition of 30 wt % FHA nanoparticles. Nanoindentation finite element simulation proved that the indenter penetration decreases from 215.54 nm to 181.46 nm with the addition of 30 wt % FHA nanoparticle. As a consequence, Chitosan-gelatin/FHA/30 wt % FHA (S4), has the best mechanical properties.

Evaluation of fluorohydroxyapatite/strontium coating on titanium implants fabricated by hydrothermal treatment.

Titanium and its alloys are considered as appropriate replacements for the irreparable bone. Calcium phosphate coatings are widely used to improve the osteoinduction and osseointegration ability of titanium alloys. To further improve the performance of the calcium phosphate-coated implants, strontium (Sr) was introduced to partially replace the calcium ions. In this study, the effect of Sr ion addition on the fluorohydroxyapatite (FHA)-coated Ti6Al4V alloy was investigated and all the coatings were treated under hydrothermal condition. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the phases and microstructures, respectively. Shear tests were done to evaluate the bond strength of the coating layer. MTT, adhesion, and alkaline phosphatase tests were performed to evaluate the biocompatibility and osteogenic behavior of the samples. Results showed that the average crystallite size for the strontium-doped FHA samples was 48nm and the bond strength had increased 13.15% in comparison with FHA-coated samples. Analysis of variance showed p value for all MTT tests at more than 0.322 and there was not any evidence of cell death after 7days. The results of the ALP test showed that the increase of the cell activity in Sr samples from day 7 to 14 is three times higher than the FHA ones.

Characterization of porous fluorohydroxyapatite bone-scaffolds fabricated using freeze casting

With the increasing demand for orthopedic and dental reconstruction surgeries, there comes a shortage of viable bone substitutes. This study was therefore designed to assess the efficacy of porous fluorohydroxyapatite (FHA) as a potential bone substitute. For this, porous FHA scaffolds were fabricated using the freeze casting technique. They were then sintered at 1250, 1350 and, 1450°C, and microstructural, mechanical, and in vitro properties were analyzed. The microstructure analyses revealed the porosity remained constant within the temperature range. However, the pore size decreased with increasing sintering temperature. The greatest compressive strength and elastic modulus were obtained at 1450°C, which were 13.5±4.0MPa and 379±182MPa, respectively. These are comparable values to human trabecular bone and other porous scaffolds made using hydroxyapatite. This analysis has thus helped to attain an understanding of the mechanical and material properties of freeze-cast FHA scaffolds that have not been presented before. In vitro studies revealed an increasing rate of human osteoblast cell proliferation on freeze-cast FHA scaffolds with increasing sintering temperature, suggesting improved osteogenic properties. Additionally, osteoblasts cells were also shown to proliferate into the interior pores of all freeze-cast FHA scaffolds. These results indicate the potential of porous FHA scaffolds fabricated using the freeze-casting technique to be utilized clinically as bone substitutes.

Microstructural Investigation of Fluoroapatite Hydrothermally Converted from Hydroxyapatite Synthesized from Crocodile Eggshell

Fluoro/hydroxyapatite (FHAp) were prepared by hydrothermal at 150 °C for 24 hours with different of starting materials. The conversion of hydroxyapatite (HAp) and tricalcium phosphate to FHAp showed the rod-like shape with 200 nm. While, the morphology of FHAp from crocodile eggshell as CaCO3 form with different in phosphorus and fluoride source showed the unique structure evolution from rod-like hexagonal crystals, dumbbell to ball shape. Two distinctive morphology, first when using NaF as fluoride source with (NH4)2HPO4 precursor show the large cubic structure in high magnification it is tufted hexagonal crystal and it bundle like structure. As the pH value decreases in NH4F, it increases crystal size. For H3PO4 as phosphate precursor found that unique structure evolution from rod-like hexagonal crystals to dumbbell structure and then form the sphere assembly with a size of several micrometers.

Incorporation of Hydroxyapatite into Glass Ionomer Cement (GIC) Formulated Based on Alumino-Silicate-Fluoride Glass Ceramics from Waste Materials

Glass ionomer cement (GIC) is a well-known restorative material applied in dentistry. The present work aims to study the effect of hydroxyapatite (HA) addition into GIC based on physical, mechanical and structural properties. The utilization of waste materials namely clam shell (CS) and soda lime silica (SLS) glass as replacements for the respective CaO and SiO2 sources in the fabrication of alumino-silicate-fluoride (ASF) glass ceramics powder. GIC was formulated based on ASF glass ceramics, polyacrylic acid (PAA) and deionized water, while 1 wt.% of HA powder was added to enhance the properties of the cement samples. The cement samples were subjected to four different ageing times before being analyzed. In this study, the addition of HA caused an increment in density and compressive strength results along with ageing time. Besides, X-ray Diffraction (XRD) revealed the formation of fluorohydroxyapatite (FHA) phase in HA-added GIC samples and it was confirmed by Fourier Transform Infrared (FTIR) analysis which detected OH‒F vibration mode. In addition, needle-like and agglomeration of spherical shapes owned by apatite crystals were observed from Field Emission Scanning Electron Microscopy (FESEM). Based on Energy Dispersive X-ray (EDX) analysis, the detection of chemical elements in the cement samples were originated from chemical compounds used in the preparation of glass ceramics powder and also the polyacid utilized in initiating the reaction of GIC.

Surface Modification of Biodegradable Mg-Based Scaffolds for Human Mesenchymal Stem Cell Proliferation and Osteogenic Differentiation.

Magnesium alloys with coatings have the potential to be used for bone substitute alternatives since their mechanical properties are close to those of human bone. However, the surface modification of magnesium alloys to increase the surface biocompatibility and reduce the degradation rate remains a challenge. Here, FHA-Mg scaffolds were made of magnesium alloys and coated with fluorohydroxyapatite (FHA). Human mesenchymal stem cells (hMSCs) were cultured on FHA-Mg scaffolds and cell viability, proliferation, and osteogenic differentiation were investigated. The results showed that FHA-Mg scaffolds display a nano-scaled needle-like structure of aggregated crystallites on their surface. The average Mg2+ concentration in the conditioned media collected from FHA-Mg scaffolds (5.8–7.6 mM) is much lower than those collected from uncoated, Mg(OH)2-coated, and hydroxyapatite (HA)-coated samples (32.1, 17.7, and 21.1 mM, respectively). In addition, compared with hMSCs cultured on a culture dish, cells cultured on FHA-Mg scaffolds demonstrated better proliferation and comparable osteogenic differentiation. To eliminate the effect of osteogenic induction medium, hMSCs were cultured on FHA-Mg scaffolds in culture medium and an approximate 66% increase in osteogenic differentiation was observed three weeks later, indicating a significant effect of the nanostructured surface of FHA-Mg scaffolds on hMSC behaviors. With controllable Mg2+ release and favorable mechanical properties, porous FHA-Mg scaffolds have a great potential in cell-based bone regeneration.

Chemical stability, antibacterial and osteogenic activities study of strontium-silver co-substituted fluorohydroxyapatite nanopillars: A potential multifunctional biological coating

The hydroxyapatite (HA) coating doped with multiple ions has attracted much attention due to its potential to impart various functions (antibacterial and osteogenic activity, etc.) to plastic surgery and dental implants. In this work, novel nano fluorohydroxyapatite (FHA) coatings substituted simultaneously with Sr2+ and Ag+ (SrAgFHA) were designed and successfully synthesized by one-step electrodeposition. Ag was used to impart antibacterial ability to SrAgFHA, and Sr can balance the potential cytotoxicity of Ag, thereby improving the cell compatibility of the composite coating. The SrAgFHA coating was consisted of closely aggregated/fused hexagonal columnar nanorods of ~100–150 nm. The nano-coating has higher corrosion resistance than FHA coating and uncoated Ti. Due to the doping of F, SrAgFHA nanorods have a complete single crystal structure and exhibit low degradability, which can ensure the long-term and slow release of Sr2+ and Ag+ ions. This nanorod coating with a low roughness and zeta potential was superhydrophobic and displayed good in vitro bioactivities, such as excellent apatite forming ability, which proves the osteoconductive nature. The results of electrochemical impedance spectroscopy confirmed that by electrodepositing the SrAgFHA coating on the Ti surface, the corrosion resistance was significantly improved. SrAgFHA coating has the best antibacterial effect and osteogenesis ability, for example, the broad-spectrum antibacterial effect on E. coli and S. aureus is 96.5 and 96.8%, respectively, and it can induce osteoblast adhesion, proliferation and differentiation. The rabbit bone defect experiment showed that a large amount of new bone was formed around the SrAgFHA coated implant, and its early bone integration ability was the strongest. In summary, SrAgFHA strikes a balance between superior corrosion resistance, cytocompatibility and excellent antibacterial properties. The multi-element co-doped HA coating has huge clinical application potential in anti-infective repair.

Pulsed electrodeposition of Ag+ doped prosthetic Fluorohydroxyapatite coatings on stainless steel substrates.

In order to reinforce the antibacterial character of fluorohydroxyapatite (FHA) prosthetic layers on 316L stainless steel (316L SS), Ag+ ions (an antibacterial agent) are included in the electrodeposition medium to be incorporated in the FHA layers created by pulsed protocol. The doped coatings (Ag-FHA) with different concentrations of silver ions (5, 10, 20, 40 and 100ppm) were characterized electrochemically (polarization curves and electrochemical impedance spectroscopy) in simulated body fluid (SBF) solution and microbiologically against two pathogenic bacteria (Staphylococcus aureus and Escherichia coli). XPS, EDX and Raman spectroscopies were used to complement these evaluations. Whatever the concentration of incorporated Ag+ ions, the FHA morphology, structure and composition are not affected. The XPS and EDX results confirm the Ag+ presence within the apatite crystals, mostly concentrated at the extreme surface of the coatings. They also show the lowering of the stoichiometry of the coatings, confirmed by Raman analyses. The corrosion studies indicate that the prosthetic coatings act as a barrier against corrosion of the 316L SS alloy. Moreover, the results of the microbiological tests show that a content of 40ppm of silver, introduced into the prosthetic coatings, inhibits the bacterial growth. Lower concentrations showing only a partial inhibition. In conclusion, using a pulsed current mode in the electrodeposition processes generates Ag-FHA/316L SS systems suitable for biomedical applications.

Synthesis of alginate/carbon nanotube/carbon dot/fluoroapatite/TiO2 beads for dye photocatalytic degradation under ultraviolet light

Fewer toxic and cost-effective catalysts such as organic-inorganic polymer composites are highly necessary for the water purification. This work describes the sono-assisted fabrication of photocatalyst including multi-walled carbon nanotubes (CNTs), carbon dots (Cdots), magnesium fluorohydroxyapatite (FA), and TiO2 nanoparticles (NPs) (CNT/Cdot/FA/TiO2) for methylene blue (MB) degradation in the water solution. This hybrid was employed for the reinforcement of crosslinked alginate (CAlg) and fabrication of CAlg/CNT/Cdot/FA/TiO2 composite. The photocatalytic behavior of this composite was examined for the MB degradation. To examine TiO2 NPs effect on the as- products, the mentioned samples were prepared without TiO2, as well. Photodegradation yields of the samples followed in the order of CNT/CD/FA/TiO2 > TiO2 NPs > CAlg/CNT/Cdot/FA/TiO2 composite > pure FA. The outcomes indicated that the TiO2 hybridization not only could postpone the recombination of photo-created electron-hole pairs but also prevented aggregation of TiO2 NPs, which led to enhancement in the photodegradation yield of MB.

Fluorine-contained hydroxyapatite suppresses bone resorption through inhibiting osteoclasts differentiation and function in vitro and in vivo.

ObjectivesFluorine, an organic trace element, has been shown to unfavourably effect osteoclasts function at a low dose. Use of hydroxyapatite (HA) has been effective in exploring its roles in promoting bone repair. In this study, we used HA modified with fluorine to investigate whether it could influence osteoclastic activity in vitro and ovariectomy‐induced osteoclasts hyperfunction in vivo.Materials and methodsFluorohydroxyapatite (FHA) was obtained and characterized by scanning electron microscope (SEM). Osteoclasts proliferation and apoptosis treated with FHA were assessed by MTT and TUNEL assay. SEM, F‐actin, TRAP activity and bone resorption experiment were performed to determine the influence of FHA on osteoclasts differentiation and function. Moreover, HA and FHA were implanted into ovariectomized osteoporotic and sham surgery rats. Histology and Micro‐CT were examined for further verification.ResultsFluorine released from FHA slowly and sustainably. FHA hampered osteoclasts proliferation, promoted osteoclasts apoptosis, suppressed osteoclasts differentiation and function. Experiments in vivo validated that FHA participation brought about an inhibitory effect on osteoclasts hyperfunction and less bone absorption.ConclusionThe results indicated that FHA served as an efficient regulator to attenuate osteoclasts formation and function and was proposed as a candidature for bone tissue engineering applications.

Characterization and evaluation of fluoridated apatites for the development of infection-free percutaneous devices

The wound healing process in the soft tissues adjacent to percutaneous implants induces “epithelial downgrowth”, and subsequently, a sinus tract around the device. This provides an optimal environment for bacterial colonization and proliferation. In an attempt to arrest downgrowth and achieve epithelial attachment to a device surface, we have sought to mimic the most common and successful percutaneous organ, the tooth. Since teeth are composed of partially and fully fluoridated forms of hydroxyapatite (HA), it was hypothesized that the surface properties of fluoridated apatites, fluorohydroxyapatite (FHA) and fluorapatite (FA), would improve epithelial cellular adhesion and differentiation when compared to HA and titanium (Ti) surfaces. In this study, the apatites (HA, FHA, and FA) were synthesized and characterized. Following a high-temperature sintering treatment of these apatites, keratinocyte and fibroblast adhesion and differentiation properties were analyzed in vitro, revealing a statistically significant increase in keratinocyte adhesion and terminal differentiation on FA surfaces sintered at 1050–1150 °C as compared to Ti or HA. Moreover, fibroblasts displayed enhanced adhesion on FHA surfaces. This data suggests that percutaneous devices coated with, or fabricated from, fluoridated apatites may induce improved epithelial cellular adhesion and differentiation, potentially limiting deeply penetrating epithelial downgrowth and resultant bacterial ingress.

PEDOT/FHA nanocomposite coatings on newly developed Ti-Nb-Zr implants: Biocompatibility and surface protection against corrosion and bacterial infections

The fabrication of bioactive polymer nanocomposite coatings with enhanced biocompatibility and surface protection has been a topic of abundant concern in orthopaedic implant applications. Herein, we electrochemically prepared a novel poly (3,4-ethylenedioxythiophene) (PEDOT) based nanocomposite coatings with different contents of fluoro hydroxyapatite (FHA) nanoparticles on a newly developed Ti-Nb-Zr (TNZ) alloy; an appropriate approach to advance the surface features of TNZ implants. FTIR, XRD, and Raman analyses of the coating confirm the successful preparation of PEDOT/FHA nanocomposite, and XPS validate the chemical interaction between FHA and PEDOT matrix. SEM and TEM examination show the uniform distribution of spherical FHA nanoparticles inside the PEDOT matrix. Hardness and contact angle measurement results showed improving in the hardness and surface wettability of the coated samples respectively. Electrochemical corrosion tests specified that the PEDOT/FHA coatings exhibit higher corrosion protection than the pure PEDOT coatings. The fabricated nanocomposite coating supports the cell adsorption and proliferation of MG-63 cells. Moreover, antibacterial studies against Gram positive and negative bacteria reveal the enhanced antibacterial performance of the coated TNZ substrates. Our results show the potential applications of PEDOT/FHA nanocomposite as a most viable coating for the orthopaedic implants.