蚕丝基生物材料精准和功能性组装的3D打印策略

In recent years,significant progress has been made in both three-dimensional(3D)printing technologies and the exploration of silk as an ink to produce biocompatible constructs.Combined with the unlimited design potential of 3D printing,silk can be processed into a broad range of functional materials and devices for various biomedical applications.The ability of silk to be processed into various materials,including solutions,hydrogels,particles,microspheres,and fibers,makes it an excellent candidate for adaptation to different 3D printing techniques.This review presents a didactic overview of the 3D printing of silk-based materials,major categories of printing techniques,and their prototyping mechanisms and structural features.In addition,we provide a roadmap for researchers aiming to incorporate silk printing into their own work by summarizing promising strategies from both technical and material aspects,to relate state-of-the-art silk-based material processing with fast-developing 3D printing technologies.Thus,our focus is on elucidating the techniques and strategies that advance the development of precise assembly strategies for silk-based materials.Precise printing(including high printing resolution,complex structure realization,and printing fidelity)is a prerequisite for the digital design capability of 3D printing technology and would definitely broaden the application era of silk,such as complex biomimetic tissue structures,vasculatures,and transdermal microneedles.

A Petrological, Geochemical, and Geochronological Study of Shuikou Ultrabasic Rock Mass in Wuding County, Yunnan Province, China

Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)N ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.

Research on the Online College English Teaching Mode from the Perspective of Autonomous Learning

In order to explore the online college English teaching mode from the perspective of autonomous learning and facilitate college students to better learn English independently as well as to master their English application skills,this article expounds the significance of online English teaching through theoretical analysis.At the same time,it expounds how to realize online English teaching in the perspective of autonomous learning,so as to improve the quality of English teaching and students’English skills.

3D-printable supramolecular hydrogels with shear-thinning property: fabricating strength tunable bioink via dual crosslinking

3-dimensional(3D)bioprinting technology provides promising strategy in the fabrication of artificial tissues and organs.As the fundamental element in bioprinting process,preparation of bioink with ideal mechanical properties without sacrifice of biocompatibility is a great challenge.In this study,a supramolecular hydrogel-based bioink is prepared by polyethylene glycol(PEG)grafted chitosan,α-cyclodextrin(α-CD)and gelatin.It has a primary crosslinking structure through the aggregation of the pseudo-polyrotaxane-like side chains,which are formed from the host-guest interactions betweenα-CD and PEG side chain.Apparent viscosity measurement shows the shear-shinning property of this bioink,which might be due to the reversibility of the physical crosslinking.Moreover,withβ-glycerophosphate at different concentrations as the secondary crosslinking agent,the printed constructs demonstrate different Young's modulus(p<0.001).They could also maintain the Young's modulus in cell culture condition for at least 21 days(p<0.05).By co-culturing each component with fibroblasts,CCK-8 assay demonstrate cellular viability is higher than 80%.After bioprinting and culturing,immunofluorescence staining with quantification indicate the expression of Ki-67,Paxillin,and N-cadherin is higher in day 14 than those in day 3(p<0.05).Oil red O and Nissl body specific staining reflect strength tunable bioink may have impact on the cell fate of mesenchymal stem cells(p<0.05).This work might provide new idea for advanced bioink in the application of re-establishing complicated tissues and organs.