Introduction It is necessary for an ideal bioceramic scaffold to have a suitable structure.The structure can affect the mechanical properties of the scaffold(i.e.,elastic modulus and compressive strength)and the biolo...Introduction It is necessary for an ideal bioceramic scaffold to have a suitable structure.The structure can affect the mechanical properties of the scaffold(i.e.,elastic modulus and compressive strength)and the biological properties of the scaffold(i.e.,degradability and cell growth rate).Lattice structure is a kind of periodic porous structure,which has some advantages of light weight and high strength,and is widely used in the preparation of bioceramic scaffolders.For the structure of the scaffold,high porosity and large pore size are important for bone growth,bone integration and promoting good mechanical interlocking between neighboring bones and the scaffold.However,scaffolds with a high porosity often lack mechanical strength.In addition,different parts of the bone have different structural requirements.In this paper,scaffolds with a non-uniform structure or a hierarchical structure were designed,with loose and porous exterior to facilitate cell adhesion,osteogenic differentiation and vascularization as well as relatively dense interior to provide sufficient mechanical support for bone repair.Methods In this work,composite ceramics scaffolds with 10%akermanite content were prepared by DLP technology.The scaffold had a high porosity outside to promote the growth of bone tissue,and a low porosity inside to withstand external forces.The compressive strength,fracture form,in-vitro degradation performance and bioactivity of graded bioceramic scaffolds were investigated.The models of scaffolds were imported into the DLP printer with a 405 nm light.The samples were printed with the intensity of 8 mJ/cm^(2)and a layer thickness of 50μm.Finally,the ceramic samples were sintered at 1100℃.The degradability of the hierarchical gyroid bioceramic scaffolds was evaluated through immersion in Tris-HCl solution and SBF solution at a ratio of 200 mL/g.The bioactivity of bioceramic was obtained via immersing them in SBF solution for two weeks.The concentrations of calcium,phosphate,silicon,and magnesium ions in the soaking solution were determined by an inductively coupled plasma optical emission spectrometer.Results and discussion In this work,a hierarchical Gyroid structure HA-AK10 scaffold(sintered at 1100℃)with a radial internal porosity of 50%and an external porosity of 70%is prepared,and the influence of structural form on the compressive strength and degradation performance of the scaffold is investigated.The biological activity of the bioceramics in vitro is also verified.The mechanical simulation results show that the stress distribution corresponds to the porosity distribution of the structure,and the low porosity is larger and the overall stress concentration phenomenon does not appear.After soaking in SBF solution,Si—OH is firstly formed on the surface of bioceramics,and then silicon gel layer is produced due to the presence of calcium and silicon ions.The silicon gel layer is dissociated into negatively charged groups under alkaline environment secondary adsorption of calcium ions and phosphate ions,forming amorphous calcium phosphate,and finally amorphous calcium phosphate crystals and adsorption of carbonate ions,forming carbonate hydroxyapatite.This indicates that the composite bioceramics have a good biological activity in-vitro and can provide a good environment for the growth of bone cells.A hierarchical Gyroid ceramic scaffold with a bone geometry is prepared via applying the hierarchical structure to the bone contour scaffold.The maximum load capacity of the hierarchical Gyroid ceramic scaffold is 8 times that of the uniform structure.Conclusions The hierarchical structure scaffold designed had good overall compressive performance,good degradation performance,and still maintained a good mechanical stability during degradation.In addition,in-vitro biological experimental results showed that the surface graded composite scaffold could have a good in-vitro biological activity and provide a good environment for bone cells.Compared to the heterosexual structure,the graded scaffold had greater mechanical properties.展开更多
In bone tissue engineering,good structural and forming qualities are prerequisites for the long-term implantation of scaffolds.To mitigate the stress-shielding effect between porous bone scaffolds and the human skelet...In bone tissue engineering,good structural and forming qualities are prerequisites for the long-term implantation of scaffolds.To mitigate the stress-shielding effect between porous bone scaffolds and the human skeleton,this study proposes a method for designing non-linear gradient gyroid porous structures with radial-axial hybrid gra-dients that are precisely controlled by multivariate polynomial functions to simulate human bone characteristics.The influence of the volumetric energy density on the forming quality of the porous structures was evaluated by characterizing the internal strut morphology and measuring the strut width and porosity.Finite element analysis combined with experimental observations revealed that during compression,the thin struts at the top and bottom of the hybrid-gradient porous structure deformed first,and the compressive stress and shear stress were gradually transferred from the thin struts at the upper and lower ends of the structure to the thicker struts in the middle.Compared with the axial gradient,the edge struts of the hybrid-gradient porous structures can withstand higher shear and compressive stresses.Furthermore,owing to the variation in the radial gradient,compared to struc-tures with 20%axial porosity variation,the hybrid-gradient porous structure with 40%radial porosity variation and 20%axial porosity variation exhibited an 18.10%increase in elastic modulus and a 4.29%increase in yield strength.Additionally,its effective energy absorption was 20.39%higher than that of the homogeneous structures.Compared to radial-gradient porous structures,the hybrid-gradient porous structure showed a lower sensitivity of the elastic modulus and yield strength to the volumetric energy density.展开更多
Improving the shape memory effect and superelasticity of Cu-based shape memory alloys(SMAs)has always been a research hotspot in many countries.This work systematically investigates the effects of Gyroid triply period...Improving the shape memory effect and superelasticity of Cu-based shape memory alloys(SMAs)has always been a research hotspot in many countries.This work systematically investigates the effects of Gyroid triply periodic minimal surface(TPMS)lattice structures with different unit sizes and volume fractions on the manufacturing viability,compressive mechanical response,superelasticity and heating recovery properties of CuAlMn SMAs.The results show that the increased specific surface area of the lattice structure leads to increased powder adhesion,making the manufacturability proportional to the unit size and volume fraction.The compressive response of the CuAlMn SMAs Gyroid TPMS lattice structure is negatively correlated with the unit size and positively correlated with the volume fraction.The superelastic recovery of all CuAlMn SMAs with Gyroid TPMS lattice structures is within 5%when the cyclic cumulative strain is set to be 10%.The lattice structure shows the maximum superelasticity when the unit size is 3.00 mm and the volume fraction is 12%,and after heating recovery,the total recovery strain increases as the volume fraction increases.This study introduces a new strategy to enhance the superelastic properties and expand the applications of CuAlMn SMAs in soft robotics,medical equipment,aerospace and other fields.展开更多
Structural coloration strategies are widely adopted in the living world to manipulate light,offering great inspiration for humans to address the challenges in creating advanced photonic materials with desired performa...Structural coloration strategies are widely adopted in the living world to manipulate light,offering great inspiration for humans to address the challenges in creating advanced photonic materials with desired performance.Among the vast photonic structures in nature,chiral photonic crystals have drawn special attention owing to their intricate 3D structure,unique chiroptical properties,and potential applications in chiral optics,pigments,information storage,and so on.In this review,we focus on the research progress in clarifying the hierarchical structures and unique optical properties of chiral photonic crystal structures found in animals and plants,including cholesteric-like one-dimensional photonic crystals and chiral gyroid structures.We summarize various top-down and bottom-up methods to mimic the biological strategy to fabricate chiral photonic crystals with comparable or better performances than their bio-counterparts.The emerging applications in sustainable photonic pigments,polarized luminescence and lasers,information storage,chiroptical devices,sensors,and radiative cooling are highlighted.We hope this review will be helpful in the design and fabrication of multifunctional chiral photonic materials inspired by nature.展开更多
文摘Introduction It is necessary for an ideal bioceramic scaffold to have a suitable structure.The structure can affect the mechanical properties of the scaffold(i.e.,elastic modulus and compressive strength)and the biological properties of the scaffold(i.e.,degradability and cell growth rate).Lattice structure is a kind of periodic porous structure,which has some advantages of light weight and high strength,and is widely used in the preparation of bioceramic scaffolders.For the structure of the scaffold,high porosity and large pore size are important for bone growth,bone integration and promoting good mechanical interlocking between neighboring bones and the scaffold.However,scaffolds with a high porosity often lack mechanical strength.In addition,different parts of the bone have different structural requirements.In this paper,scaffolds with a non-uniform structure or a hierarchical structure were designed,with loose and porous exterior to facilitate cell adhesion,osteogenic differentiation and vascularization as well as relatively dense interior to provide sufficient mechanical support for bone repair.Methods In this work,composite ceramics scaffolds with 10%akermanite content were prepared by DLP technology.The scaffold had a high porosity outside to promote the growth of bone tissue,and a low porosity inside to withstand external forces.The compressive strength,fracture form,in-vitro degradation performance and bioactivity of graded bioceramic scaffolds were investigated.The models of scaffolds were imported into the DLP printer with a 405 nm light.The samples were printed with the intensity of 8 mJ/cm^(2)and a layer thickness of 50μm.Finally,the ceramic samples were sintered at 1100℃.The degradability of the hierarchical gyroid bioceramic scaffolds was evaluated through immersion in Tris-HCl solution and SBF solution at a ratio of 200 mL/g.The bioactivity of bioceramic was obtained via immersing them in SBF solution for two weeks.The concentrations of calcium,phosphate,silicon,and magnesium ions in the soaking solution were determined by an inductively coupled plasma optical emission spectrometer.Results and discussion In this work,a hierarchical Gyroid structure HA-AK10 scaffold(sintered at 1100℃)with a radial internal porosity of 50%and an external porosity of 70%is prepared,and the influence of structural form on the compressive strength and degradation performance of the scaffold is investigated.The biological activity of the bioceramics in vitro is also verified.The mechanical simulation results show that the stress distribution corresponds to the porosity distribution of the structure,and the low porosity is larger and the overall stress concentration phenomenon does not appear.After soaking in SBF solution,Si—OH is firstly formed on the surface of bioceramics,and then silicon gel layer is produced due to the presence of calcium and silicon ions.The silicon gel layer is dissociated into negatively charged groups under alkaline environment secondary adsorption of calcium ions and phosphate ions,forming amorphous calcium phosphate,and finally amorphous calcium phosphate crystals and adsorption of carbonate ions,forming carbonate hydroxyapatite.This indicates that the composite bioceramics have a good biological activity in-vitro and can provide a good environment for the growth of bone cells.A hierarchical Gyroid ceramic scaffold with a bone geometry is prepared via applying the hierarchical structure to the bone contour scaffold.The maximum load capacity of the hierarchical Gyroid ceramic scaffold is 8 times that of the uniform structure.Conclusions The hierarchical structure scaffold designed had good overall compressive performance,good degradation performance,and still maintained a good mechanical stability during degradation.In addition,in-vitro biological experimental results showed that the surface graded composite scaffold could have a good in-vitro biological activity and provide a good environment for bone cells.Compared to the heterosexual structure,the graded scaffold had greater mechanical properties.
基金supported by National Natural Science Foundation of China(Grant No.52175481)Postdoctoral Science Foundation of China(Grant No.2023M743539).
文摘In bone tissue engineering,good structural and forming qualities are prerequisites for the long-term implantation of scaffolds.To mitigate the stress-shielding effect between porous bone scaffolds and the human skeleton,this study proposes a method for designing non-linear gradient gyroid porous structures with radial-axial hybrid gra-dients that are precisely controlled by multivariate polynomial functions to simulate human bone characteristics.The influence of the volumetric energy density on the forming quality of the porous structures was evaluated by characterizing the internal strut morphology and measuring the strut width and porosity.Finite element analysis combined with experimental observations revealed that during compression,the thin struts at the top and bottom of the hybrid-gradient porous structure deformed first,and the compressive stress and shear stress were gradually transferred from the thin struts at the upper and lower ends of the structure to the thicker struts in the middle.Compared with the axial gradient,the edge struts of the hybrid-gradient porous structures can withstand higher shear and compressive stresses.Furthermore,owing to the variation in the radial gradient,compared to struc-tures with 20%axial porosity variation,the hybrid-gradient porous structure with 40%radial porosity variation and 20%axial porosity variation exhibited an 18.10%increase in elastic modulus and a 4.29%increase in yield strength.Additionally,its effective energy absorption was 20.39%higher than that of the homogeneous structures.Compared to radial-gradient porous structures,the hybrid-gradient porous structure showed a lower sensitivity of the elastic modulus and yield strength to the volumetric energy density.
基金supported by the National Natural Science Foundation of China(No.51974028)the Fundamental Research Funds for the Central Universities(No.2021JCCXJD01)the Key R&D and transformation projects in Qinghai Province(No.2023-HZ-801).
文摘Improving the shape memory effect and superelasticity of Cu-based shape memory alloys(SMAs)has always been a research hotspot in many countries.This work systematically investigates the effects of Gyroid triply periodic minimal surface(TPMS)lattice structures with different unit sizes and volume fractions on the manufacturing viability,compressive mechanical response,superelasticity and heating recovery properties of CuAlMn SMAs.The results show that the increased specific surface area of the lattice structure leads to increased powder adhesion,making the manufacturability proportional to the unit size and volume fraction.The compressive response of the CuAlMn SMAs Gyroid TPMS lattice structure is negatively correlated with the unit size and positively correlated with the volume fraction.The superelastic recovery of all CuAlMn SMAs with Gyroid TPMS lattice structures is within 5%when the cyclic cumulative strain is set to be 10%.The lattice structure shows the maximum superelasticity when the unit size is 3.00 mm and the volume fraction is 12%,and after heating recovery,the total recovery strain increases as the volume fraction increases.This study introduces a new strategy to enhance the superelastic properties and expand the applications of CuAlMn SMAs in soft robotics,medical equipment,aerospace and other fields.
基金supported by the National Key R&D Program of China(2021YFA1200302 and 2022YFA1205400,Tang Z)Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000,Tang Z)+1 种基金National Natural Science Foundation of China(92056204,92356304,Tang Z,and 22275042,Gao X)Major Project of Wenzhou Institute,University of Chinese Academy of Sciences(WIUCASQD2020011,Gao X)。
文摘Structural coloration strategies are widely adopted in the living world to manipulate light,offering great inspiration for humans to address the challenges in creating advanced photonic materials with desired performance.Among the vast photonic structures in nature,chiral photonic crystals have drawn special attention owing to their intricate 3D structure,unique chiroptical properties,and potential applications in chiral optics,pigments,information storage,and so on.In this review,we focus on the research progress in clarifying the hierarchical structures and unique optical properties of chiral photonic crystal structures found in animals and plants,including cholesteric-like one-dimensional photonic crystals and chiral gyroid structures.We summarize various top-down and bottom-up methods to mimic the biological strategy to fabricate chiral photonic crystals with comparable or better performances than their bio-counterparts.The emerging applications in sustainable photonic pigments,polarized luminescence and lasers,information storage,chiroptical devices,sensors,and radiative cooling are highlighted.We hope this review will be helpful in the design and fabrication of multifunctional chiral photonic materials inspired by nature.
