Laser three-dimensional(3D)printing offers significant advantages in integrating the shape and function of regen-erative tissues through biomimetic manufacturing.However,its effectiveness is limited by the lack of spe...Laser three-dimensional(3D)printing offers significant advantages in integrating the shape and function of regen-erative tissues through biomimetic manufacturing.However,its effectiveness is limited by the lack of specialized biopolymer powders-while solvent methods that use residual solvents produce powders with poor biocompati-bility,mechanical methods result in irregularly shaped crystals.In this study,a biopolymer powder spheroidiza-tion and shaping technology,which utilizes the evolution of irregular powders into spheres with minimal surface free energy in the molten state,is proposed based on the thermodynamic principle of minimum energy.Initially,the motion trajectory and temperature field of the poly(L-lactic acid)(PLLA)powder during spheroidization were quantitatively assessed and optimized using Stokes’law and Fourier’s principle.Subsequently,the cohesive forces and aggregation kinetics of the polymer chains were calculated using molecular dynamics.Finally,based on these calculations,a phase-field model was constructed to simulate the evolution of the spheroidization rate and deduce the optimal parameters for the process.This precise approach enhances PLLA spheroidization control for laser 3D printing,improves part densification and surface quality,and offers a clean and efficient path for preparing high-quality PLLA spheroidized powder for laser 3D printing.展开更多
Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical appl...Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical application.In this study,reduced graphene oxide(RGO)was used as reinforcement in Zn scaffold fabricated via laser additive manufacturing.Results showed that the homogeneously dispersed RGO simultaneously enhanced the strength and ductility of Zn scaffold.On one hand,the enhanced strength was ascribed to(i)the grain refinement caused by the pinning effect of RGO,(ii)the efficient load shift due to the huge specific surface area of RGO and the favorable interface bonding between RGO and Zn matrix,and(iii)the Orowan strengthening by the homogeneously distributed RGO.On the other hand,the improved ductility was owing to the RGO-induced random orientation of grain with texture index reducing from 20.5 to 7.3,which activated more slip systems and provided more space to accommodate dislocation.Furthermore,the cell test confirmed that RGO promoted cell growth and differentiation.This study demonstrated the great potential of RGO in tailoring the mechanical performance and cell behavior of Zn scaffold for bone repair.展开更多
基金supported by National Key Research and Development Program of China(Grant No.2023YFB4605800)Natural Science Foundation of China(Grant Nos.51935014,52365046,52105352,82072084)+1 种基金JiangXi Provincial Natural Science Foundation of China(Grant No.20224ACB204013)Schig-Qinling Program(Grant No.2022360702014891).
文摘Laser three-dimensional(3D)printing offers significant advantages in integrating the shape and function of regen-erative tissues through biomimetic manufacturing.However,its effectiveness is limited by the lack of specialized biopolymer powders-while solvent methods that use residual solvents produce powders with poor biocompati-bility,mechanical methods result in irregularly shaped crystals.In this study,a biopolymer powder spheroidiza-tion and shaping technology,which utilizes the evolution of irregular powders into spheres with minimal surface free energy in the molten state,is proposed based on the thermodynamic principle of minimum energy.Initially,the motion trajectory and temperature field of the poly(L-lactic acid)(PLLA)powder during spheroidization were quantitatively assessed and optimized using Stokes’law and Fourier’s principle.Subsequently,the cohesive forces and aggregation kinetics of the polymer chains were calculated using molecular dynamics.Finally,based on these calculations,a phase-field model was constructed to simulate the evolution of the spheroidization rate and deduce the optimal parameters for the process.This precise approach enhances PLLA spheroidization control for laser 3D printing,improves part densification and surface quality,and offers a clean and efficient path for preparing high-quality PLLA spheroidized powder for laser 3D printing.
基金The Natural Science Foundation of China(51935014,81871494,81871498)JiangXi Provincial Natural Science Foundation of China(20192ACB20005,2020ACB214004,20202BAB214011)+5 种基金The Provincial Key R&D Projects of Jiangxi(20201BBE51012)Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme(2018)The Project of Hunan Provincial Science and Technology Plan(2017RS3008)Shenzhen Science and Technology Plan Project(JCYJ20170817112445033)Innovation Team Project on University of Guangdong Province(2018GKCXTD001)Technology Innovation Platform Project of Shenzhen Institute of Information Technology 2020(PT2020E002).
文摘Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical application.In this study,reduced graphene oxide(RGO)was used as reinforcement in Zn scaffold fabricated via laser additive manufacturing.Results showed that the homogeneously dispersed RGO simultaneously enhanced the strength and ductility of Zn scaffold.On one hand,the enhanced strength was ascribed to(i)the grain refinement caused by the pinning effect of RGO,(ii)the efficient load shift due to the huge specific surface area of RGO and the favorable interface bonding between RGO and Zn matrix,and(iii)the Orowan strengthening by the homogeneously distributed RGO.On the other hand,the improved ductility was owing to the RGO-induced random orientation of grain with texture index reducing from 20.5 to 7.3,which activated more slip systems and provided more space to accommodate dislocation.Furthermore,the cell test confirmed that RGO promoted cell growth and differentiation.This study demonstrated the great potential of RGO in tailoring the mechanical performance and cell behavior of Zn scaffold for bone repair.
