3D Bioprinting for Tissue and Organ Fabrication

The field of regenerative medicine has progressed tremendously over the past few decades in its ability to fabricate functional tissue substitutes. Conventional approaches based on scaffolding and microengineering are limited in their capacity of producing tissue constructs with precise biomimetic properties. Three-dimensional (3D) bioprinting technology, on the other hand, promises to bridge the divergence between artificially engineered tissue constructs and native tissues. In a sense, 3D bioprinting offers unprecedented versatility to co-deliver cells and biomaterials with precise control over their compositions, spatial distributions, and architectural accuracy, therefore achieving detailed or even personalized recapitulation of the fine shape, structure, and architecture of target tissues and organs. Here we briefly describe recent progresses of 3D bioprinting technology and associated bioinks suitable for the printing process. We then focus on the applications of this technology in fabrication of biomimetic constructs of several representative tissues and organs, including blood vessel, heart, liver, and cartilage. We finally conclude with future challenges in 3D bioprinting as well as potential solutions for further development.United States. Office of Naval Research. Young Investigator ProgramNational Institutes of Health (U.S.) (Grants EB012597, AR057837, DE021468, HL099073 and R56AI105024)Presidential Early Career Award for Scientists and Engineer

Carbon-contacted single molecule electrical junctions

International audienceA fully metal-free molecular junction (MJ) has been built by using an electrochemically etched carbon fibre STM tip as the top electrode and graphene as the bottom electrode. The corresponding conductance values for 1,n-alkanediamine and 1,$n$-alkanedithiol ($n$ = 2, 4, 6, 8 and 10) have been measured using the STM-$I$(s) technique. The tunnelling decay constant of the alkanediamine and alkanedithiol junctions with these carbon contacts is much lower than the corresponding metal contacted junctions of 0.24 and 0.38 per –CH_2 unit, but the junction conductance with these carbon contacts is also lower. The carbon fibre tip can be considered a good candidate as an electrode. Compared with a gold tip, the carbon fibre tip leads to correspondingly lower molecular junction conductanc

Fast and straightforward analysis approach of charge transport data in single molecule junctions

International audienceIn this study, we introduce an efficient data sorting algorithm, including filters for noisy signals, conductance mapping for analyzing the most dominant conductance group and sub-population groups. The capacity of our data analysis process has also been corroborated on real experimental data sets of Au-1,6-hexanedithiol-Au and Au-1,8-octanedithiol-Au molecular junctions. The fully automated and unsupervised program requires less than one minute on a standard PC to sort the data and generate histograms. The resulting one-dimensional and two-dimensional log histograms give conductance values in good agreement with previous studies. Our algorithm is a straightforward, fast and user-friendly tool for single molecule charge transport data analysis. We also analyze the data in a form of a conductance map which can offer evidence for diversity in molecular conductance. The code for automatic data analysis is openly available, well-documented and ready to use, thereby offering a useful new tool for single molecule electronics

Vibrational spectroscopy and microwave dielectric properties of AY2Si3O10 (A=Sr, Ba) ceramics for 5G applications

AY2Si3O10 (A = Sr, Ba) trisilicate ceramics were synthesized by traditional high temperature solid state reaction method. X-ray diffraction patterns and Rietveld refinement revealed that AY2Si3O10 (A = Sr, Ba) ceramics belonged to triclinic and monoclinic crystal systems with Pī and P21/m space groups, respectively. The vibrational modes of [SiO4] tetrahedra, [YO6] octahedra and [(Sr/Ba)O8] polyhedra were analyzed by Raman spectroscopy. The infrared spectroscopy fitting analysis was used to determine intrinsic dielectric properties. Excellent microwave dielectric properties were measured for SrY2Si3O10 and BaY2Si3O10 with ɛr = 9.3, Qf = 64100 GHz, τf = −31 ppm/°C and ɛr = 9.5, Qf = 65600 GHz, τf = −28 ppm/°C, respectively. Both trisilicate ceramics are considered potential candidates for 5G and mm wave technology, provided τf can be further tuned

Recent Progress in Fabrication and Physical Properties of 2D TMDC-Based Multilayered Vertical Heterostructures

Two-dimensional (2D) vertical heterojunctions (HSs), which are usually fabricated by vertically stacking two layers of transition metal dichalcogenide (TMDC), have been intensively researched during the past years. However, it is still an enormous challenge to achieve controllable preparation of the TMDC trilayer or multilayered van der Waals (vdWs) HSs, which have important effects on physical properties and device performance. In this review, we will introduce fundamental features and various fabrication methods of diverse TMDC-based multilayered vdWs HSs. This review focuses on four fabrication methods of TMDC-based multilayered vdWs HSs, such as exfoliation, chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), and pulsed laser deposition (PLD). The latest progress in vdWs HS-related novel physical phenomena are summarized, including interlayer excitons, long photocarrier lifetimes, upconversion photoluminescence, and improved photoelectrochemical catalysis. At last, current challenges and prospects in this research field are provided

Recent Progress in Fabrication and Physical Properties of 2D TMDC-Based Multilayered Vertical Heterostructures

Two-dimensional (2D) vertical heterojunctions (HSs), which are usually fabricated by vertically stacking two layers of transition metal dichalcogenide (TMDC), have been intensively researched during the past years. However, it is still an enormous challenge to achieve controllable preparation of the TMDC trilayer or multilayered van der Waals (vdWs) HSs, which have important effects on physical properties and device performance. In this review, we will introduce fundamental features and various fabrication methods of diverse TMDC-based multilayered vdWs HSs. This review focuses on four fabrication methods of TMDC-based multilayered vdWs HSs, such as exfoliation, chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), and pulsed laser deposition (PLD). The latest progress in vdWs HS-related novel physical phenomena are summarized, including interlayer excitons, long photocarrier lifetimes, upconversion photoluminescence, and improved photoelectrochemical catalysis. At last, current challenges and prospects in this research field are provided

Nanoscale mapping of intrinsic defects in single-layer graphene using tip-enhanced Raman spectroscopy

Non-gap mode tip-enhanced Raman spectroscopy (TERS) is used for the first time to successfully map the intrinsic defects in single-layer graphene with 20 nm spatial resolution. The nanoscale Raman mapping is enabled by an unprecedented near-field to far-field signal contrast of 8.5 at the Ag-coated TERS tip-apex. These results demonstrate the potential of TERS for characterisation of defects in single-layer graphene-based devices at the nanometre length-scale