Chitin hydrogel has been recognized as a promising material for various biomedical applications because of its biocompatibility and biodegradability.However,the fabrication of strong chitin hydrogel remains a big chal...Chitin hydrogel has been recognized as a promising material for various biomedical applications because of its biocompatibility and biodegradability.However,the fabrication of strong chitin hydrogel remains a big challenge because of the insolubility of chitin in many solvents and the reduced chain length of chitin regenerated from solutions.We herein introduce the fabrication of chitin hydrogel with biomimetic structure through the chemical transformation of chitosan,which is a water-soluble deacetylated derivative of chitin.The reacetylation of the amino group in chitosan endows the obtained chitin hydrogel with outstanding resistance to swelling,degradation,extreme temperature and pH conditions,and organic solvents.The chitin hydrogel has excellent mechanical properties while retaining a high water content(more than 95 wt.%).It also shows excellent antifouling performance that it resists the adhesion of proteins,bacteria,blood,and cells.Moreover,as the initial chitosan solution can be feasibly frozen and templated by ice crystals,the chitin hydrogel structure can be either nacre-like or wood-like depending on the freezing method of the precursory chitosan solution.Owing to these anisotropic structures,such chitin hydrogel can exhibit anisotropic mechanics and mass transfer capabilities.The current work provides a rational strategy to fabricate chitin hydrogels and paves the way for its practical applications as a superior biomedical material.展开更多
Biological structural materials,despite consisting of limited kinds of compounds,display multifunctionalities due to their complex hierarchical architectures.While some biomimetic strategies have been applied in artif...Biological structural materials,despite consisting of limited kinds of compounds,display multifunctionalities due to their complex hierarchical architectures.While some biomimetic strategies have been applied in artificial materials to enhance their mechanical stability,the simultaneous optimization of other functions along with the mechanical properties via biomimetic designs has not been thoroughly investigated.Herein,iron oxide/carbon nanotube(CNT)-based artificial nacre with both improved mechanical and electromagnetic interference(EMI)shielding performance is fabricated via the mineralization of Fe_(3)O_(4)onto a CNTincorporated matrix.The micro-and nano-structures of the artificial nacre are similar to those of natural nacre,which in turn improves its mechanical properties.The alternating electromagnetic wave-reflective CNT layers and the wave-absorptive iron oxide layers can improve the multiple reflections of the waves on the surfaces of the reflection layers,which then allows sufficient interactions between the waves and the absorption layers.Consequently,compared with the reflection-dependent EMI-shielding of the non-structured material,the artificial nacre exhibits strong absorption-dependent shielding behavior even with a very low content of wave-absorptive phase.Owing to the high mechanical stability,the shielding effectiveness of the artificial nacre that deeply cut by a blade is still maintained at approximately 70%−96%depending on the incident wave frequency.The present work provides a new way for designing structural materials with concurrently enhanced mechanical and functional properties,and a path to combine structural design and intrinsic properties of specific materials via a biomimetic strategy.展开更多
The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradie...The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradients,have rarely been incorporated in biomimetic ceramicsbecause of the challenges in simultaneously controlling the materialstructure at multiple length scales.Here,we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite plateletsthrough a matrix-directed mineralization method.The gradients areformed via the spontaneous accumulation of graphene oxide nanosheetson the surface of the platelets during the mineralization process,whichthen induces a lateral residual stress field in the platelets.Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsicallythrough the compressive stress near the platelet surface.The energydissipation density reaches 0.159±0.007 nJ/μm^(3),and the toughnessamplification is superior to that of the most advanced cer amics.Numer-ical simulations also agree with the finding that the stress field not ablycontributes to the overall energy dissipation.This work demonstratesthat the energy dissipation of biomimetic ceramics can be furtherincreased by integrating design principles spanning multiple scales.This strategy can be readily extended to the combinations of other struc-tural models for the design and fabrication of structural ceramics withcustomized and optimized performance.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2018YFE0202201 and 2021YFA0715700)the National Natural Science Foundation of China(Nos.21701161 and 22293044)the Key Scientific Research Foundation of the Education Department of Anhui Province(No.2022AH050702)。
文摘Chitin hydrogel has been recognized as a promising material for various biomedical applications because of its biocompatibility and biodegradability.However,the fabrication of strong chitin hydrogel remains a big challenge because of the insolubility of chitin in many solvents and the reduced chain length of chitin regenerated from solutions.We herein introduce the fabrication of chitin hydrogel with biomimetic structure through the chemical transformation of chitosan,which is a water-soluble deacetylated derivative of chitin.The reacetylation of the amino group in chitosan endows the obtained chitin hydrogel with outstanding resistance to swelling,degradation,extreme temperature and pH conditions,and organic solvents.The chitin hydrogel has excellent mechanical properties while retaining a high water content(more than 95 wt.%).It also shows excellent antifouling performance that it resists the adhesion of proteins,bacteria,blood,and cells.Moreover,as the initial chitosan solution can be feasibly frozen and templated by ice crystals,the chitin hydrogel structure can be either nacre-like or wood-like depending on the freezing method of the precursory chitosan solution.Owing to these anisotropic structures,such chitin hydrogel can exhibit anisotropic mechanics and mass transfer capabilities.The current work provides a rational strategy to fabricate chitin hydrogels and paves the way for its practical applications as a superior biomedical material.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB 0470303 and XDB 0450402)the National Key Research and Development Program of China(Nos.2018YFE0202201 and 2021YFA0715700)+2 种基金the National Natural Science Foundation of China(Nos.22293044,U1932213,and 22305240)the New Cornerstone Investigator Program.Y.-F.M.acknowledges the Major Basic Research Project of Anhui Province(No.2023z04020009)the Double First-Class University Construction Fund from USTC(No.YD2060002037).
文摘Biological structural materials,despite consisting of limited kinds of compounds,display multifunctionalities due to their complex hierarchical architectures.While some biomimetic strategies have been applied in artificial materials to enhance their mechanical stability,the simultaneous optimization of other functions along with the mechanical properties via biomimetic designs has not been thoroughly investigated.Herein,iron oxide/carbon nanotube(CNT)-based artificial nacre with both improved mechanical and electromagnetic interference(EMI)shielding performance is fabricated via the mineralization of Fe_(3)O_(4)onto a CNTincorporated matrix.The micro-and nano-structures of the artificial nacre are similar to those of natural nacre,which in turn improves its mechanical properties.The alternating electromagnetic wave-reflective CNT layers and the wave-absorptive iron oxide layers can improve the multiple reflections of the waves on the surfaces of the reflection layers,which then allows sufficient interactions between the waves and the absorption layers.Consequently,compared with the reflection-dependent EMI-shielding of the non-structured material,the artificial nacre exhibits strong absorption-dependent shielding behavior even with a very low content of wave-absorptive phase.Owing to the high mechanical stability,the shielding effectiveness of the artificial nacre that deeply cut by a blade is still maintained at approximately 70%−96%depending on the incident wave frequency.The present work provides a new way for designing structural materials with concurrently enhanced mechanical and functional properties,and a path to combine structural design and intrinsic properties of specific materials via a biomimetic strategy.
基金Strategic Priority Research Program of the Chinese Acad-emy of Sciences(XDB 0470000)National Key Research and Development Program of China(2018YFE0202201 and 2021YFA0715700)+4 种基金National Natural Science Foundation of China(22305240 and 22293044)Y.F.M.acknowledges the funding suported by the Students'Innovation and Entrepreneurship Foundation of USTC(XY2022S02)Double First-Class University Construction Fund from USTC(YD2060002037)New Comerstone Science FoundationThis work was parially carried out at the USTC Center for Micro-and Nanoscale Research and Fabrication.This research used Beamline BL14B and BL15U of the Shanghai Synchrotron Radiation Fa cility(SSRF).
文摘The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradients,have rarely been incorporated in biomimetic ceramicsbecause of the challenges in simultaneously controlling the materialstructure at multiple length scales.Here,we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite plateletsthrough a matrix-directed mineralization method.The gradients areformed via the spontaneous accumulation of graphene oxide nanosheetson the surface of the platelets during the mineralization process,whichthen induces a lateral residual stress field in the platelets.Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsicallythrough the compressive stress near the platelet surface.The energydissipation density reaches 0.159±0.007 nJ/μm^(3),and the toughnessamplification is superior to that of the most advanced cer amics.Numer-ical simulations also agree with the finding that the stress field not ablycontributes to the overall energy dissipation.This work demonstratesthat the energy dissipation of biomimetic ceramics can be furtherincreased by integrating design principles spanning multiple scales.This strategy can be readily extended to the combinations of other struc-tural models for the design and fabrication of structural ceramics withcustomized and optimized performance.