As implanted bone fixation materials,magnesium(Mg)alloys have significant advantages because the density and elastic modulus are closest to those of the human bone and they can bio-degrade in the physiological environ...As implanted bone fixation materials,magnesium(Mg)alloys have significant advantages because the density and elastic modulus are closest to those of the human bone and they can bio-degrade in the physiological environment.However,Mg alloys degrade too rapidly and uncontrollably thus hampering clinical adoption.In this study,a highly corrosion-resistant zinc-phosphate-doped micro-arc oxidation(MAO)coating is prepared on the AZ31B alloy,and the degradation process is assessed in vitro.With increasing zinc phosphate concentrations,both the corrosion potentials and charge transfer resistance of the AZ31B alloy coated with MAO coatings increase gradually,while the corrosion current densities di-minish gradually.Immersion tests in the simulated body fluid(SBF)reveal that the increased zinc phos-phate concentration in MAO coating decreases the degradation rate,consequently reducing the release rates of Mg^(2+)and OH-in the physiological micro-environment,which obtains the lowest weight loss of only 5.22%after immersion for 56 days.Effective regulation of degradation provides a weak alkaline environment that is suitable for long-term cell growth and subsequent promotion of bone proliferation,differentiation,mineralization,and cytocompatibility.In addition,the zinc-phosphate-doped MAO coat-ings show an improved wear resistance as manifested by a wear rate of only 3.81 x 10^(-5) mm^(3) N^(-1) m^(-1).The results reveal a suitable strategy to improve the properties of biodegradable Mg alloys to balance tissue healing with mechanical degradation.展开更多
Hydrophobic/superhydrophobic materials with intrinsic water repellence are highly desirable in engineering fields including antiicing in aerocrafts,antidrag and anticorrosion in ships,and antifog and self-cleaning in ...Hydrophobic/superhydrophobic materials with intrinsic water repellence are highly desirable in engineering fields including antiicing in aerocrafts,antidrag and anticorrosion in ships,and antifog and self-cleaning in optical lenses,screen,mirrors,and windows.However,superhydrophobic material should have small surface energy(SE)and a micro/nanosurface structure which can reduce solid-liquid contact significantly.The low SE is generally found in organic materials with inferior mechanical properties that is undesirable in engineering.Intriguingly,previous theoretical calculations have predicted a negative SE forθ-alumina(θ-Al_(2)O_(3)),which inspires us to use it as a superhydrophobic material.Here,we report the experimental evidence of the small/negative SE ofθ-Al_(2)O_(3) and aθ-Al_(2)O_(3)-based superhydrophobic coating prepared by one-step scalable plasma arcing oxidation.The superhydrophobic coating has complete ceramic and desired micro/nanostructure and therefore exhibits excellent aging resistance,wear resistance,corrosion resistance,high-temperature tolerance,and burning resistance.Owing to the rarity of the small/negative SE in inorganic materials,the concept to reduce SE byθ-Al_(2)O_(3) may foster a blowout to develop robust superhydrophobicity by complete inorganic materials.展开更多
基金Shenzhen-Hong Kong Research and Development Fund(No.SGDX20201103095406024)2022 Shenzhen Sustainable Supporting Funds for Colleges and Universities(No.20220810143642004)+9 种基金Shenzhen Basic Research Project(Nos.JCYJ20200109144608205 and JCYJ20210324120001003)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515011301 and 2021A1515012246)Peking University Shenzhen Graduate School Research Start-up Fund of Introducing Talent(No.1270110273)Shenzhen Postdoctoral Research Fund Project after Outbound(No.2129933651)China Postdoctoral Science Foundation(No.2023M730032)City University of Hong Kong Strategic Research Grants(SRG)(7005505)City University of Hong Kong Donation Research Grants(No.9220061 and DON-RMG No.9229021)Guangdong-Hong Kong Technology Cooperation Funding Scheme(TCFS)(No.GHP/085/18SZ)Shenzhen-Hong Kong Technology Cooperation Funding Scheme(TCFS)(No.GHP/149/20SZ and CityU 9440296)IER Foundation(Nos.IERF2020001 and IERF202102).
文摘As implanted bone fixation materials,magnesium(Mg)alloys have significant advantages because the density and elastic modulus are closest to those of the human bone and they can bio-degrade in the physiological environment.However,Mg alloys degrade too rapidly and uncontrollably thus hampering clinical adoption.In this study,a highly corrosion-resistant zinc-phosphate-doped micro-arc oxidation(MAO)coating is prepared on the AZ31B alloy,and the degradation process is assessed in vitro.With increasing zinc phosphate concentrations,both the corrosion potentials and charge transfer resistance of the AZ31B alloy coated with MAO coatings increase gradually,while the corrosion current densities di-minish gradually.Immersion tests in the simulated body fluid(SBF)reveal that the increased zinc phos-phate concentration in MAO coating decreases the degradation rate,consequently reducing the release rates of Mg^(2+)and OH-in the physiological micro-environment,which obtains the lowest weight loss of only 5.22%after immersion for 56 days.Effective regulation of degradation provides a weak alkaline environment that is suitable for long-term cell growth and subsequent promotion of bone proliferation,differentiation,mineralization,and cytocompatibility.In addition,the zinc-phosphate-doped MAO coat-ings show an improved wear resistance as manifested by a wear rate of only 3.81 x 10^(-5) mm^(3) N^(-1) m^(-1).The results reveal a suitable strategy to improve the properties of biodegradable Mg alloys to balance tissue healing with mechanical degradation.
基金This work was financially supported by the National Key R&D Program of China(2016YFB0700600)the Guangdong Innovation Team Project(No.2013N080)+2 种基金the Soft Science Research Project of Guangdong Province(No.2017B030301013)the Shenzhen Science and Technology Research Grant(ZDSYS201707281026184 and JCYJ20170306165240649)the Hong Kong Innovation and Technology Fund(ITF)ITS/452/17FP(CityU 9440179).We are very appreciative for the advices of Prof.Lei Jiang in the paper writing。
文摘Hydrophobic/superhydrophobic materials with intrinsic water repellence are highly desirable in engineering fields including antiicing in aerocrafts,antidrag and anticorrosion in ships,and antifog and self-cleaning in optical lenses,screen,mirrors,and windows.However,superhydrophobic material should have small surface energy(SE)and a micro/nanosurface structure which can reduce solid-liquid contact significantly.The low SE is generally found in organic materials with inferior mechanical properties that is undesirable in engineering.Intriguingly,previous theoretical calculations have predicted a negative SE forθ-alumina(θ-Al_(2)O_(3)),which inspires us to use it as a superhydrophobic material.Here,we report the experimental evidence of the small/negative SE ofθ-Al_(2)O_(3) and aθ-Al_(2)O_(3)-based superhydrophobic coating prepared by one-step scalable plasma arcing oxidation.The superhydrophobic coating has complete ceramic and desired micro/nanostructure and therefore exhibits excellent aging resistance,wear resistance,corrosion resistance,high-temperature tolerance,and burning resistance.Owing to the rarity of the small/negative SE in inorganic materials,the concept to reduce SE byθ-Al_(2)O_(3) may foster a blowout to develop robust superhydrophobicity by complete inorganic materials.
