Given the alarmingly increasing rates of glaucoma worldwide and the lack of satisfactory treatments,there is a dire need to explore more feasible treatment options.Magnesium(Mg)is an essential element in maintaining t...Given the alarmingly increasing rates of glaucoma worldwide and the lack of satisfactory treatments,there is a dire need to explore more feasible treatment options.Magnesium(Mg)is an essential element in maintaining the functional and structural integrity of vital ocular tissues,but Mg and its alloys are rarely mentioned in ophthalmic applications.Our previous research found that hydroxyapatite-coated Mg(Mg@HA)shows the best biocompatibility and bioactivity,and exhibits the effect of inhibiting fibrosis after filtration surgery in the rabbit model,which is expected to be a promising material for glaucoma drainage device.In this study,we further demonstrated the anti-fibrosis effect of Mg@HA from the molecular signal level and the efficacy of implantation in the rabbit filtration surgery model.In vitro experiments showed the surface modification of Mg affects the adhesion behavior and the reorganization of cytoskeleton of Human Western blot analysis and immunofluorescence found that Mg@HA regulates the adhesion and motility of human Tenon’s capsule fibroblasts mainly by down-regulating the phosphorylation of Smad2 and Smad3 in the canonical transforming growth factor-beta(TGF-β)signaling pathway.By observing and recording the condition of filtering blebs and intraocular pressure after surgery,the effectiveness of Mg@HA applied in the rabbit filtration surgery model was further evaluated.In conclusion,the application of hydroxyapatite-coated Mg in the eye has good biocompatibility and has the potential to resist postoperative glaucoma filtration fibrosis,which may be mediated by the regulation of the TGFβ/Smad signaling pathway.展开更多
Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a phy...Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a physiological condition limits their wide applications.Hence,hydroxyapatite(HAp)coatings on Mg alloys have attracted much attention to address this corrosion issue and enhance the surface functionalities.In this paper,we present a review of HAp coating strategies on Mg alloys,including the sol-gel method,hydrothermal treatment,biomimetic coating,electrochemical deposition,electrophoretic deposition,and plasma electrolytic oxidation technique,and their recent progress to enhance the surface characteristics of Mg alloys.This review focused on aspects of coating morphology,hybrid formulations,and how they influence corrosion behavior as well as in vitro and in vivo performance.Moreover,we have discussed the future prospects of HAp-coating strategies,emphasizing on multifunctional,hybrid,and smart coatings for next-generation implant materials.展开更多
Magnesium is a candidate metal for biodegradable implant applications for its biodegradation tendency and excellent biocompatibility.Unfortunately,the high degradation rate of magnesium and also its localized degradat...Magnesium is a candidate metal for biodegradable implant applications for its biodegradation tendency and excellent biocompatibility.Unfortunately,the high degradation rate of magnesium and also its localized degradation in physiological conditions are the main issues for its successful implant applications.The degradation rate of magnesium has been reduced to some degree via alloying,but the localized degradation susceptibility is a great concern.For many years,hydroxyapatite(HAp),a biocompatible ceramic material,has been extensively used for bio-implant applications.Recently,a substantial amount of research has been carried out on coating HAp on magnesium-based materials for improved degradation resistance in particular and also to enhance the biocompatibility.This review article focuses on the different methods of HAp coating on magnesium-based materials and also the recent cutting-edge advancements made in the coating process for improved degradation resistance and biocompatibility.The mechanical stability of the HAp coated magnesium-based materials is also discussed.展开更多
A polymethyltrimethoxysilane（PMTMS）/hydroxyapatite（HA） hybrid coating was successfully fabricated on a magnesium alloy by hydrothermal treatment and immersion method. The microstructure and composition of the coat...A polymethyltrimethoxysilane（PMTMS）/hydroxyapatite（HA） hybrid coating was successfully fabricated on a magnesium alloy by hydrothermal treatment and immersion method. The microstructure and composition of the coating were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy.The physical properties were investigated using scratch testing. At the same time, the corrosion resistance was evaluated via electrochemical and immersion tests. The results demonstrated that the corrosion resistance of the silane hybrid coating was significantly enhanced compared with the naked magnesium alloy. Especially, the corrosion current density of the PMTMS/HA magnesium alloy was three orders of magnitude lower than that of the bare material.展开更多
Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechan...Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.展开更多
To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydroth...To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid（PASP） and ethylenediaminetetraacetic acid（EDTA） were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid（SBF） demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.展开更多
This work is focused on developing zinc-doped hydroxyapatite-zeolite(Zn HA-Zeo)and polycaprolactone(PCL)composite coatings on magnesium(Mg)substrate to improve the corrosion resistance and antimicrobial properties.Dip...This work is focused on developing zinc-doped hydroxyapatite-zeolite(Zn HA-Zeo)and polycaprolactone(PCL)composite coatings on magnesium(Mg)substrate to improve the corrosion resistance and antimicrobial properties.Dip-coating technique was used to coat Zn HA-Zeo/PCL on the Mg substrate at room temperature.The samples were subjected to field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Fourier transform infrared(FTIR),energy dispersive X-ray spectroscopy(EDX)and antimicrobial potential.Results demonstrated that composite coatings consist of HA,scholzite,zeolite,and PCL phases.EDX spectra indicated the presence of calcium(Ca),silicon(Si),aluminum(Al),zinc(Zn),phosphorus(P)and oxygen(O).The composite surface appeared in spherical-like microstructure on coating with thickness ranging 226-260μm.Zinc-doped HA-Zeo composite coating had a high corrosion resistance and provided sufficient protection to the Mg surface against galvanic corrosion.Doped Zn HA-Zeo coating samples exhibited superior disc inhibition by confirming antimicrobial activity against the E.coli as compared to HA-Zeo sample.Altogether these results showed that the Zn HA-Zeo coatings not only improved the corrosion resistance,but also enhanced the antimicrobial property and hence they can be used as suitable candidates for implant applications.展开更多
Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coat...Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coating was synthesized on Ti O2-coated Mg alloy by physical vapour deposition（PVD） assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction（XRD） analysis and field emission scanning electron microscopy（FE-SEM） images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O2 film with a thickness of 1 μm. The potentiodynamic polarization（PDP） and electrochemical impedance spectroscopy（EIS） tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid（SBF） solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone（3.86 mm） towards Escherichia coli（E. coli） compared with the Ti O2-coated Mg alloy（2.61 mm）. The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.展开更多
Magnesium-based biomaterials have been in extensive research for orthopedic applications for decades due to their optimal mechanical features and osteopromotive nature;nevertheless,rapid degradation restricts their cl...Magnesium-based biomaterials have been in extensive research for orthopedic applications for decades due to their optimal mechanical features and osteopromotive nature;nevertheless,rapid degradation restricts their clinical applicability.In this study,pristine magnesium was purified(P-Mg)using a melt self-purification approach and reinforced using indigenously synthesized nanohydroxyapatite(HAP,0.6 wt.%)and strontium substituted nanohydroxyapatite(SrHAP,0.6 wt.%)using a low-cost stir assisted squeeze casting method to control their degradation rate.Using electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD)examinations,all casted materials were carefully evaluated for microstructure and phase analysis.Mechanical characteristics,in vitro degradation,and in vitro biocompatibility with murine pre-osteoblasts were also tested on the fabricated alloys.For in vivo examination of bone formation,osteointegration,and degradation rate,the magnesium-based alloys were fabricated as small cylindrical pins with a diameter of 2.7 mm and a height of 2 mm.The pins were implanted in a critical-sized defect in a rat femur shaft(2.7 mm diameter and 2 mm depth)for 8 weeks and evaluated by microCT and histological evaluation for bone growth and osteointegration.When compared to P-Mg and P-MgHAP,micro-CT and histological analyses revealed that the P-MgSrHAP group had the highest bone formation towards the periphery of the implant and hence maximum osteointegration.When the removed pins from the bone defect were analyzed using GIXRD,they displayed hydroxyapatite peaks that were consistent with bio-integration.For P-Mg,P-MgHAP,and P-MgSrHAP 8 weeks after implantation,in vivo degradation rates derived from micro-CT were around 0.6 mm/year,0.5 mm/year,and 0.1 mm/year,respectively.Finally,P-MgSrHAP possesses the requisite degradation rate as well as sufficient mechanical and biological properties,indicating that it has the potential to be used in the development/fabrication of biodegradable bioactive orthopaedic implants.展开更多
AZ91/HA composite was prepared by AZ91 magnesium alloy and porous HA using squeeze casting method. The microstructure and mechanical property of the AZ91/HA composite were studied. The results show that the molten AZ9...AZ91/HA composite was prepared by AZ91 magnesium alloy and porous HA using squeeze casting method. The microstructure and mechanical property of the AZ91/HA composite were studied. The results show that the molten AZ91 alloy completely infiltrated the preform without destroying the porous structure of the HA preform. The compressive strength of AZ91/HA composite increased significantly compared with that of the porous HA. The immersion test indicated that AzgI ahoy shows a lower corrosion resistance and is easier to be corroded in comparison with HA.展开更多
Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)an...Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.展开更多
Magnesium （Mg）-hydroxyapatite （Calo（PO4）6（OH）2, abbreviated as HA） composite films have been grown on Mg plates using a pulsed laser deposition technique. Mechanical property measurements and analysis have ind...Magnesium （Mg）-hydroxyapatite （Calo（PO4）6（OH）2, abbreviated as HA） composite films have been grown on Mg plates using a pulsed laser deposition technique. Mechanical property measurements and analysis have indicated that hardness and Young＇s modulus of nMg-（100-n）HA composite coatings increase with Mg content in the coatings and reach a maximum at a 70Mg-30HA composition, n and 100-n in the nMg-（100-n）HA represent the relative number of laser pulses impinging on Mg and HA targets, respectively. Direct current potentiodynamic polarization studies have shown that the corrosion of Mg plate （control） decreases with an increase in the HA ratio in the composite films. For example, the corrosion current density of Mg plate reduces by ~350 times after coating the Mg plate with 10Mg-90HA composite film. The reduction in corrosion current density of Mg plates was also accompanied by a positive shift in the corrosion potential （~6%） due to this coating. The mechanism behind the reduction in corrosion behavior of Mg plates due to nMg-（100-n） HA composite coatings has been understood by electrochemical impedance spectroscopy.展开更多
Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a fill...Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a filler into a matrix, composed of calcium aluminosilicate GICs and Poly-acrylic acid (PAA) in varying ratios. The tested ratios were Glass:PAA = 2:1 and Glass:HA:PAA = 2:0.5:1 to improve the mechanical strength of a conventional GIC. Mechanical properties, including compressive, flexural, and diametral tensile strength were studied at different setting times. The compressive strength (CS) was improved with hydroxyapatite addition and prolonged setting time while diametral tensile strength (DTS) did not follow any specific trend. The flexural strength (FS) of the composite cement was increased with increasing setting time regardless of the particle size of hydroxyapatite. The FTIR spectra of hydroxyapatite of particle sizes 15 μm and 30 μm are similar but for HA-GIC composites, the FTIR spectra, the peak around 1460 cm−1 are due to C-H and the peak at 1553 cm−1 is due to calcium carboxylate with calcium in a bridging mode which would be an excellent material that chemically bonds to the tooth structure, making it effective for both restorative procedures and cavity fillings. Scanning electron microscopy (SEM) microstructural study revealed that the glass particles were wrenched out, which was a cohesive fracture. The X-ray diffraction (XRD) pattern showed that the hydroxyapatite has a crystalline single-phase, hexagonal structure. The sharp peaks between the 2-theta range of 30 - 40 degrees are the same as in enamel powder. The spectra indicate the pure set cement as amorphous since there is no prominent peak, but with the addition of hydroxyapatite filler, the peak in the 2-theta range of 20 - 35 degrees is ascribed to crystalline apatite structure. The results indicate that incorporating hydroxyapatite into GIC significantly enhances its mechanical properties and structural integrity, suggesting its potential as an improved material for dental and restorative applications.展开更多
Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional co...Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional coatings is crucial due to the rapid degradation behavior of Mg.In this study,the function of 2D lamellar Ti_(3)C_(2)T_(x)(MXene)in Hydroxyapatite(HA)and Halloysite nanotube(HNT)hybrid coatings in biodegradable poly-(lactic acid)(PLA)was investigated.The morphological and structural characterizations of the coatings on Mg were revealed through HRTEM,XPS,SEM-EDX,XRD,FTIR,and contact angle analyses/tests.Electrochemical in vitro corrosion tests(OCP,PDS,and EIS-Nyquist)were conducted for evaluate corrosion resistance under simulated body fluid(SBF)conditions.The bioactivity of the coatings in SBF have been revealed in accordance with the ISO 23,317 standard.Finally,antibacterial disk diffusion tests were conducted to investigate the functional effect of MXene in coatings.It has been determined that the presence of MXene in the coating increased not only surface wettability(131°,85°,77°,and 74°for uncoated,pH,PHH,and PHH/MXene coatings,respectively)but also increased corrosion resistance(1857.850,42.357,1.593,and 0.085×10^(-6),A/cm^(2) for uncoated,pH,PHH,and PHH/MXene coatings,respectively).It has been proven that the in vitro bioactivity of PLA-HA coatings is further enhanced by adding HNT and MXene,along with SEM morphologies after SBF.Finally,2D lamellar MXene-filled coating exhibits antibacterial behavior against both E.coli and S.aureus bacteria.展开更多
Biological apatites contain several elements as traces. In this work, Magnesium and fluorine co-substituted hydroxyapatites with the general formula Ca9Mg(PO4)6(OH)2-yFy, where y = 0, 0.5, 1, 1.5 and 2 were synthesize...Biological apatites contain several elements as traces. In this work, Magnesium and fluorine co-substituted hydroxyapatites with the general formula Ca9Mg(PO4)6(OH)2-yFy, where y = 0, 0.5, 1, 1.5 and 2 were synthesized by the hydrothermal method. After calcination at 500℃, the samples were pressureless sintered between 950℃ and 1250℃. The substitution of F- for OH- had a strong influence on the densification behavior and mechanical properties of the materials. Below 1200℃, the density steeply decreased for y = 0.5 sample. XRD analysis revealed that compared to hydroxylfluorapatite containing no magnesium, the substituted hydroxyfluorapatites decomposed, and the nature of the decomposition products is tightly dependent on the fluorine content. The hardness, elastic modulus and fracture toughness of these materials were investigated by Vickers’s hardness testing. The highest values were 622 ± 4 GPa, 181 ± 1 GPa and 1.85 ± 0.06 MPa.m1/2, respectively.展开更多
The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of...The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of Three-Dimensional(3D)-printed Polycaprolactone(PCL)scaffolds with varying proportions of Nanohydroxyapatite(NHA)and Nanoclay(NC),and their physiochemical and biological properties were assessed.The mechanical properties of PCL are satisfactory;however,its hydrophobic nature and long-term degradation hinder its use in scaffold fabrication.NHA and NC have been employed to improve the hydrophilic characteristics,mechanical strength,adhesive properties,biocompatibility,biodegradability,and osteoconductive behavior of PCL.The morphology results demonstrated 3D-printed structures with interconnected rectangular macropores and proper nanoparticle distribution.The sample containing 70 wt%NC showed the highest porosity(65.98±2.54%),leading to an increased degradation rate.The compressive strength ranged from 10.65±1.90 to 84.93±9.93 MPa,which is directly proportional to the compressive strength of cancellous bone(2–12 MPa).The wettability,water uptake,and biodegradability of PCL scaffolds considerably improved as the amount of NC increased.The results of the cellular assays exhibited increased proliferation,viability,and adhesion of MG-63 cells due to the addition of NHA and NC to the scaffolds.Finally,according to the in vitro results,it can be concluded that 3D-printed samples with higher amounts of NC can be regarded as a suitable scaffold for expediting the regeneration process of bone defects.展开更多
Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethan...Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethane(PU),and Polycaprolactone(PCL),along with nanohydroxyapatite(nHA),an essential osteoconductive ceramic.The main objective was the development and characterization of scaffolds obtained by Rotary Jet Spinning(RJS)using PLLA,PU,and PCL incorporated with nHA,for bone-related applications.The resulting scaffolds exhibited uniform fiber morphology and a rough surface,ideal for effective bone-tissue interaction.The crystallinity indicated the scaffolds’bioactivity by apatite deposition in simulated body fluid.In addition,in vitro biological assays using preosteoblastic cells showed the biocompatibility of cells based on cell viability and adhesion parameters on the scaffolds.The results underscore the capacity of scaffolds incorporating nHA to promote both cell proliferation and osteoconduction,which are key elements essential for achieving effective bone regeneration.展开更多
The dry reforming of methane(DRM)reaction can directly convert methane(CH_(4))and carbon dioxide(CO_(2))into syngas(H_(2)+CO),which is a promising method for achieving carbon neutralization.In this study,a series of 3...The dry reforming of methane(DRM)reaction can directly convert methane(CH_(4))and carbon dioxide(CO_(2))into syngas(H_(2)+CO),which is a promising method for achieving carbon neutralization.In this study,a series of 3Ni-xCo/Mg1HAP alloy catalysts with different ratio were synthesized by the coprecipitation method,and the optimum Ni-Co ratio for the DRM reaction was studied.A series of characterization methods revealed that after Co was added,the formation of Ni-Co alloys increased the interactions between metals.However,an excess of Co inhibits the entry of Ni into the lattice of Mg_(1)HAP,resulting in metal accumulation on the surface of the support.In addition,the introduction of Co improves the dispersion of Ni metal,which endows the catalyst with better catalytic activity and stability.Raman spectroscopy of the catalyst after the stability test showed that the addition of Co reduced the proportion of graphitic carbon,which was also the main reason for its improved stability.展开更多
Micro-sized anatase TiO_(2) displays inferior capacity as cathode material for magnesium ion batteries because of the higher diffusion energy barrier of Mg^(2+)in anatase TiO_(2) lattice.Herein,we report that nanosize...Micro-sized anatase TiO_(2) displays inferior capacity as cathode material for magnesium ion batteries because of the higher diffusion energy barrier of Mg^(2+)in anatase TiO_(2) lattice.Herein,we report that nanosized anatase TiO_(2) exposed(001)facet doubles the capacity compared to the micro-sized sample ascribed to the interfacial Mg^(2+)ion storage.First-principles calculations reveal that the diffusion energy barrier of Mg^(2+)on the(001)facet is significantly lower than those in the bulk phase and on(100)facet,and the adsorption energy of Mg^(2+)on the(001)facet is also considerably lower than that on(100)facet,which guarantees superior interfacial Mg^(2+)storage of(001)facet.Moreover,anatase TiO_(2) exposed(001)facet displays a significantly higher capacity of 312.9 mAh g^(−1) in Mg-Li dual-salt electrolyte compared to 234.3 mAh g^(−1) in Li salt electrolyte.The adsorption energies of Mg^(2+)on(001)facet are much lower than the adsorption energies of Li+on(001)facet,implying that the Mg^(2+)ion interfacial storage is more favorable.These results highlight that controlling the crystal facet of the nanocrystals effectively enhances the interfacial storage of multivalent ions.This work offers valuable guidance for the rational design of high-capacity storage systems.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.81670860 and 81700836)Natural Science Foundation of Chongqing(Grant No.cstc2018jcyjAX0034 and cstc2018jcyjAX0016).
文摘Given the alarmingly increasing rates of glaucoma worldwide and the lack of satisfactory treatments,there is a dire need to explore more feasible treatment options.Magnesium(Mg)is an essential element in maintaining the functional and structural integrity of vital ocular tissues,but Mg and its alloys are rarely mentioned in ophthalmic applications.Our previous research found that hydroxyapatite-coated Mg(Mg@HA)shows the best biocompatibility and bioactivity,and exhibits the effect of inhibiting fibrosis after filtration surgery in the rabbit model,which is expected to be a promising material for glaucoma drainage device.In this study,we further demonstrated the anti-fibrosis effect of Mg@HA from the molecular signal level and the efficacy of implantation in the rabbit filtration surgery model.In vitro experiments showed the surface modification of Mg affects the adhesion behavior and the reorganization of cytoskeleton of Human Western blot analysis and immunofluorescence found that Mg@HA regulates the adhesion and motility of human Tenon’s capsule fibroblasts mainly by down-regulating the phosphorylation of Smad2 and Smad3 in the canonical transforming growth factor-beta(TGF-β)signaling pathway.By observing and recording the condition of filtering blebs and intraocular pressure after surgery,the effectiveness of Mg@HA applied in the rabbit filtration surgery model was further evaluated.In conclusion,the application of hydroxyapatite-coated Mg in the eye has good biocompatibility and has the potential to resist postoperative glaucoma filtration fibrosis,which may be mediated by the regulation of the TGFβ/Smad signaling pathway.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Small Group Research Project under grant number RGP1/34/46 (RGP1/34/46)
文摘Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a physiological condition limits their wide applications.Hence,hydroxyapatite(HAp)coatings on Mg alloys have attracted much attention to address this corrosion issue and enhance the surface functionalities.In this paper,we present a review of HAp coating strategies on Mg alloys,including the sol-gel method,hydrothermal treatment,biomimetic coating,electrochemical deposition,electrophoretic deposition,and plasma electrolytic oxidation technique,and their recent progress to enhance the surface characteristics of Mg alloys.This review focused on aspects of coating morphology,hybrid formulations,and how they influence corrosion behavior as well as in vitro and in vivo performance.Moreover,we have discussed the future prospects of HAp-coating strategies,emphasizing on multifunctional,hybrid,and smart coatings for next-generation implant materials.
基金National Natural Science Foundation of China(Grant No.52071191)Open Foundation of Hubei Key Laboratory of Advanced Technology for Automotive Components(No.XDQCKF2021006)。
文摘Magnesium is a candidate metal for biodegradable implant applications for its biodegradation tendency and excellent biocompatibility.Unfortunately,the high degradation rate of magnesium and also its localized degradation in physiological conditions are the main issues for its successful implant applications.The degradation rate of magnesium has been reduced to some degree via alloying,but the localized degradation susceptibility is a great concern.For many years,hydroxyapatite(HAp),a biocompatible ceramic material,has been extensively used for bio-implant applications.Recently,a substantial amount of research has been carried out on coating HAp on magnesium-based materials for improved degradation resistance in particular and also to enhance the biocompatibility.This review article focuses on the different methods of HAp coating on magnesium-based materials and also the recent cutting-edge advancements made in the coating process for improved degradation resistance and biocompatibility.The mechanical stability of the HAp coated magnesium-based materials is also discussed.
基金supported by the National Natural Science Foundation of China (No. 51571134)the Shandong University of Science and Technology (SDUST) Research Fund (No. 2014TDJH104)
文摘A polymethyltrimethoxysilane（PMTMS）/hydroxyapatite（HA） hybrid coating was successfully fabricated on a magnesium alloy by hydrothermal treatment and immersion method. The microstructure and composition of the coating were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy.The physical properties were investigated using scratch testing. At the same time, the corrosion resistance was evaluated via electrochemical and immersion tests. The results demonstrated that the corrosion resistance of the silane hybrid coating was significantly enhanced compared with the naked magnesium alloy. Especially, the corrosion current density of the PMTMS/HA magnesium alloy was three orders of magnitude lower than that of the bare material.
基金sponsored by the National Natural Science Foundation of China ( 51571150,11572222)Tianjin Natural Science Foundation ( 14JCYBJC16900)
文摘Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.
基金Funded by Shandong Provincial Natural Science Foundation,China(No.ZR2014EMM019)
文摘To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid（PASP） and ethylenediaminetetraacetic acid（EDTA） were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid（SBF） demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.
基金supported by University of Engineering and Technology,Lahore,faculty under research project#ORIC/102-ASRB/1288 and UTM,FRGS grant#R.J130000.7845.4F768.
文摘This work is focused on developing zinc-doped hydroxyapatite-zeolite(Zn HA-Zeo)and polycaprolactone(PCL)composite coatings on magnesium(Mg)substrate to improve the corrosion resistance and antimicrobial properties.Dip-coating technique was used to coat Zn HA-Zeo/PCL on the Mg substrate at room temperature.The samples were subjected to field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Fourier transform infrared(FTIR),energy dispersive X-ray spectroscopy(EDX)and antimicrobial potential.Results demonstrated that composite coatings consist of HA,scholzite,zeolite,and PCL phases.EDX spectra indicated the presence of calcium(Ca),silicon(Si),aluminum(Al),zinc(Zn),phosphorus(P)and oxygen(O).The composite surface appeared in spherical-like microstructure on coating with thickness ranging 226-260μm.Zinc-doped HA-Zeo composite coating had a high corrosion resistance and provided sufficient protection to the Mg surface against galvanic corrosion.Doped Zn HA-Zeo coating samples exhibited superior disc inhibition by confirming antimicrobial activity against the E.coli as compared to HA-Zeo sample.Altogether these results showed that the Zn HA-Zeo coatings not only improved the corrosion resistance,but also enhanced the antimicrobial property and hence they can be used as suitable candidates for implant applications.
文摘Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coating was synthesized on Ti O2-coated Mg alloy by physical vapour deposition（PVD） assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction（XRD） analysis and field emission scanning electron microscopy（FE-SEM） images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O2 film with a thickness of 1 μm. The potentiodynamic polarization（PDP） and electrochemical impedance spectroscopy（EIS） tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid（SBF） solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone（3.86 mm） towards Escherichia coli（E. coli） compared with the Ti O2-coated Mg alloy（2.61 mm）. The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.
基金the funding received from Ministry of Human Resource Development(MHRD),India and Indian Council of Medical Research(ICMR),India projects(IMPRINT-6714UAY/MHRD_IITK_006),MHRD,India project(SPARC/2018–2019/P612/S)+3 种基金Science and Engineering Research Board(SERB),India project(IPA/2020/000026)Department of Science and Technology(DST),Govt.of India project(DST/NM/NT-2018/48)Department of Biotechnology(DBT),Govt.of India project(DBT/IN/SWEDEN/08/AK/2017–18)Ortho Regenics Private Limited(ORPL)。
文摘Magnesium-based biomaterials have been in extensive research for orthopedic applications for decades due to their optimal mechanical features and osteopromotive nature;nevertheless,rapid degradation restricts their clinical applicability.In this study,pristine magnesium was purified(P-Mg)using a melt self-purification approach and reinforced using indigenously synthesized nanohydroxyapatite(HAP,0.6 wt.%)and strontium substituted nanohydroxyapatite(SrHAP,0.6 wt.%)using a low-cost stir assisted squeeze casting method to control their degradation rate.Using electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD)examinations,all casted materials were carefully evaluated for microstructure and phase analysis.Mechanical characteristics,in vitro degradation,and in vitro biocompatibility with murine pre-osteoblasts were also tested on the fabricated alloys.For in vivo examination of bone formation,osteointegration,and degradation rate,the magnesium-based alloys were fabricated as small cylindrical pins with a diameter of 2.7 mm and a height of 2 mm.The pins were implanted in a critical-sized defect in a rat femur shaft(2.7 mm diameter and 2 mm depth)for 8 weeks and evaluated by microCT and histological evaluation for bone growth and osteointegration.When compared to P-Mg and P-MgHAP,micro-CT and histological analyses revealed that the P-MgSrHAP group had the highest bone formation towards the periphery of the implant and hence maximum osteointegration.When the removed pins from the bone defect were analyzed using GIXRD,they displayed hydroxyapatite peaks that were consistent with bio-integration.For P-Mg,P-MgHAP,and P-MgSrHAP 8 weeks after implantation,in vivo degradation rates derived from micro-CT were around 0.6 mm/year,0.5 mm/year,and 0.1 mm/year,respectively.Finally,P-MgSrHAP possesses the requisite degradation rate as well as sufficient mechanical and biological properties,indicating that it has the potential to be used in the development/fabrication of biodegradable bioactive orthopaedic implants.
基金supported by the Medicine-Engineering Cross Research Foundation of Shanghai Jiao Tong University(Grants No.YG2014MS41)
文摘AZ91/HA composite was prepared by AZ91 magnesium alloy and porous HA using squeeze casting method. The microstructure and mechanical property of the AZ91/HA composite were studied. The results show that the molten AZ91 alloy completely infiltrated the preform without destroying the porous structure of the HA preform. The compressive strength of AZ91/HA composite increased significantly compared with that of the porous HA. The immersion test indicated that AzgI ahoy shows a lower corrosion resistance and is easier to be corroded in comparison with HA.
文摘Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.
文摘Magnesium （Mg）-hydroxyapatite （Calo（PO4）6（OH）2, abbreviated as HA） composite films have been grown on Mg plates using a pulsed laser deposition technique. Mechanical property measurements and analysis have indicated that hardness and Young＇s modulus of nMg-（100-n）HA composite coatings increase with Mg content in the coatings and reach a maximum at a 70Mg-30HA composition, n and 100-n in the nMg-（100-n）HA represent the relative number of laser pulses impinging on Mg and HA targets, respectively. Direct current potentiodynamic polarization studies have shown that the corrosion of Mg plate （control） decreases with an increase in the HA ratio in the composite films. For example, the corrosion current density of Mg plate reduces by ~350 times after coating the Mg plate with 10Mg-90HA composite film. The reduction in corrosion current density of Mg plates was also accompanied by a positive shift in the corrosion potential （~6%） due to this coating. The mechanism behind the reduction in corrosion behavior of Mg plates due to nMg-（100-n） HA composite coatings has been understood by electrochemical impedance spectroscopy.
文摘Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a filler into a matrix, composed of calcium aluminosilicate GICs and Poly-acrylic acid (PAA) in varying ratios. The tested ratios were Glass:PAA = 2:1 and Glass:HA:PAA = 2:0.5:1 to improve the mechanical strength of a conventional GIC. Mechanical properties, including compressive, flexural, and diametral tensile strength were studied at different setting times. The compressive strength (CS) was improved with hydroxyapatite addition and prolonged setting time while diametral tensile strength (DTS) did not follow any specific trend. The flexural strength (FS) of the composite cement was increased with increasing setting time regardless of the particle size of hydroxyapatite. The FTIR spectra of hydroxyapatite of particle sizes 15 μm and 30 μm are similar but for HA-GIC composites, the FTIR spectra, the peak around 1460 cm−1 are due to C-H and the peak at 1553 cm−1 is due to calcium carboxylate with calcium in a bridging mode which would be an excellent material that chemically bonds to the tooth structure, making it effective for both restorative procedures and cavity fillings. Scanning electron microscopy (SEM) microstructural study revealed that the glass particles were wrenched out, which was a cohesive fracture. The X-ray diffraction (XRD) pattern showed that the hydroxyapatite has a crystalline single-phase, hexagonal structure. The sharp peaks between the 2-theta range of 30 - 40 degrees are the same as in enamel powder. The spectra indicate the pure set cement as amorphous since there is no prominent peak, but with the addition of hydroxyapatite filler, the peak in the 2-theta range of 20 - 35 degrees is ascribed to crystalline apatite structure. The results indicate that incorporating hydroxyapatite into GIC significantly enhances its mechanical properties and structural integrity, suggesting its potential as an improved material for dental and restorative applications.
文摘Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional coatings is crucial due to the rapid degradation behavior of Mg.In this study,the function of 2D lamellar Ti_(3)C_(2)T_(x)(MXene)in Hydroxyapatite(HA)and Halloysite nanotube(HNT)hybrid coatings in biodegradable poly-(lactic acid)(PLA)was investigated.The morphological and structural characterizations of the coatings on Mg were revealed through HRTEM,XPS,SEM-EDX,XRD,FTIR,and contact angle analyses/tests.Electrochemical in vitro corrosion tests(OCP,PDS,and EIS-Nyquist)were conducted for evaluate corrosion resistance under simulated body fluid(SBF)conditions.The bioactivity of the coatings in SBF have been revealed in accordance with the ISO 23,317 standard.Finally,antibacterial disk diffusion tests were conducted to investigate the functional effect of MXene in coatings.It has been determined that the presence of MXene in the coating increased not only surface wettability(131°,85°,77°,and 74°for uncoated,pH,PHH,and PHH/MXene coatings,respectively)but also increased corrosion resistance(1857.850,42.357,1.593,and 0.085×10^(-6),A/cm^(2) for uncoated,pH,PHH,and PHH/MXene coatings,respectively).It has been proven that the in vitro bioactivity of PLA-HA coatings is further enhanced by adding HNT and MXene,along with SEM morphologies after SBF.Finally,2D lamellar MXene-filled coating exhibits antibacterial behavior against both E.coli and S.aureus bacteria.
文摘Biological apatites contain several elements as traces. In this work, Magnesium and fluorine co-substituted hydroxyapatites with the general formula Ca9Mg(PO4)6(OH)2-yFy, where y = 0, 0.5, 1, 1.5 and 2 were synthesized by the hydrothermal method. After calcination at 500℃, the samples were pressureless sintered between 950℃ and 1250℃. The substitution of F- for OH- had a strong influence on the densification behavior and mechanical properties of the materials. Below 1200℃, the density steeply decreased for y = 0.5 sample. XRD analysis revealed that compared to hydroxylfluorapatite containing no magnesium, the substituted hydroxyfluorapatites decomposed, and the nature of the decomposition products is tightly dependent on the fluorine content. The hardness, elastic modulus and fracture toughness of these materials were investigated by Vickers’s hardness testing. The highest values were 622 ± 4 GPa, 181 ± 1 GPa and 1.85 ± 0.06 MPa.m1/2, respectively.
文摘The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of Three-Dimensional(3D)-printed Polycaprolactone(PCL)scaffolds with varying proportions of Nanohydroxyapatite(NHA)and Nanoclay(NC),and their physiochemical and biological properties were assessed.The mechanical properties of PCL are satisfactory;however,its hydrophobic nature and long-term degradation hinder its use in scaffold fabrication.NHA and NC have been employed to improve the hydrophilic characteristics,mechanical strength,adhesive properties,biocompatibility,biodegradability,and osteoconductive behavior of PCL.The morphology results demonstrated 3D-printed structures with interconnected rectangular macropores and proper nanoparticle distribution.The sample containing 70 wt%NC showed the highest porosity(65.98±2.54%),leading to an increased degradation rate.The compressive strength ranged from 10.65±1.90 to 84.93±9.93 MPa,which is directly proportional to the compressive strength of cancellous bone(2–12 MPa).The wettability,water uptake,and biodegradability of PCL scaffolds considerably improved as the amount of NC increased.The results of the cellular assays exhibited increased proliferation,viability,and adhesion of MG-63 cells due to the addition of NHA and NC to the scaffolds.Finally,according to the in vitro results,it can be concluded that 3D-printed samples with higher amounts of NC can be regarded as a suitable scaffold for expediting the regeneration process of bone defects.
基金financial support from FAPESP-Sao Paulo Research Foundation[grants #2020/07923-0,and #2023/11076-0]the National Council for Scientific and Technological Development-CNPq[grant #406514/2021-6].
文摘Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethane(PU),and Polycaprolactone(PCL),along with nanohydroxyapatite(nHA),an essential osteoconductive ceramic.The main objective was the development and characterization of scaffolds obtained by Rotary Jet Spinning(RJS)using PLLA,PU,and PCL incorporated with nHA,for bone-related applications.The resulting scaffolds exhibited uniform fiber morphology and a rough surface,ideal for effective bone-tissue interaction.The crystallinity indicated the scaffolds’bioactivity by apatite deposition in simulated body fluid.In addition,in vitro biological assays using preosteoblastic cells showed the biocompatibility of cells based on cell viability and adhesion parameters on the scaffolds.The results underscore the capacity of scaffolds incorporating nHA to promote both cell proliferation and osteoconduction,which are key elements essential for achieving effective bone regeneration.
基金supported by the Guangxi Natural Science Foundation(2020GXNSFDA297007)the National Natural Science Foundation of China(22078074)the Special Funding for‘Guangxi Bagui Scholars’.
文摘The dry reforming of methane(DRM)reaction can directly convert methane(CH_(4))and carbon dioxide(CO_(2))into syngas(H_(2)+CO),which is a promising method for achieving carbon neutralization.In this study,a series of 3Ni-xCo/Mg1HAP alloy catalysts with different ratio were synthesized by the coprecipitation method,and the optimum Ni-Co ratio for the DRM reaction was studied.A series of characterization methods revealed that after Co was added,the formation of Ni-Co alloys increased the interactions between metals.However,an excess of Co inhibits the entry of Ni into the lattice of Mg_(1)HAP,resulting in metal accumulation on the surface of the support.In addition,the introduction of Co improves the dispersion of Ni metal,which endows the catalyst with better catalytic activity and stability.Raman spectroscopy of the catalyst after the stability test showed that the addition of Co reduced the proportion of graphitic carbon,which was also the main reason for its improved stability.
基金supported by the National Key R&D Program of China(No.2023YFB3809500)the Fundamental Research Funds for the Central Universities(No.2024CDJXY003)+1 种基金the Venture&Innovation Support Program for Chongqing Overseas Returnees(cx2023087)The Chongqing Technology Innovation and Application Development Project(No.2024TIAD-KPX0003).
文摘Micro-sized anatase TiO_(2) displays inferior capacity as cathode material for magnesium ion batteries because of the higher diffusion energy barrier of Mg^(2+)in anatase TiO_(2) lattice.Herein,we report that nanosized anatase TiO_(2) exposed(001)facet doubles the capacity compared to the micro-sized sample ascribed to the interfacial Mg^(2+)ion storage.First-principles calculations reveal that the diffusion energy barrier of Mg^(2+)on the(001)facet is significantly lower than those in the bulk phase and on(100)facet,and the adsorption energy of Mg^(2+)on the(001)facet is also considerably lower than that on(100)facet,which guarantees superior interfacial Mg^(2+)storage of(001)facet.Moreover,anatase TiO_(2) exposed(001)facet displays a significantly higher capacity of 312.9 mAh g^(−1) in Mg-Li dual-salt electrolyte compared to 234.3 mAh g^(−1) in Li salt electrolyte.The adsorption energies of Mg^(2+)on(001)facet are much lower than the adsorption energies of Li+on(001)facet,implying that the Mg^(2+)ion interfacial storage is more favorable.These results highlight that controlling the crystal facet of the nanocrystals effectively enhances the interfacial storage of multivalent ions.This work offers valuable guidance for the rational design of high-capacity storage systems.
