A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom‐up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N‐isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm–PDMS substrates optimal for VSMC attachment. To allow long‐term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm–PDMS surfaces were further modified with 3‐aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single‐layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single‐layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.

     

Thin Poly(Di(Ethylene Glycol)Methyl Ether Methacrylate) Homopolymer Brushes Allow Controlled Adsorption and Desorption of PaTu 8988t Cells

Poly(di(ethylene glycol)methyl ether methacrylate) (PDEGMA) brushes, which are known to suppress protein adsorption and prevent cell attachment, are reported here to possess interesting and tunable thermoresponsive behavior, if the brush thickness is reduced or the grafting density is altered. PDEGMA brushes with a dry ellipsometric thickness of 5 ± 1 nm can be switched from cell adherent behavior at 37 °C to cell nonadherent at 25 °C. This behavior coincides with the temperature‐dependent irreversible adsorption of fibronectin from phosphate saline buffer and proteins present in the cell culture medium, as unveiled by surface plasmon resonance measurements. Unlike for tissue culture polystyrene reference surfaces, swelling of the PDEGMA chains below the lower critical solution temperature results in the absence of paxillin and actin containing cellular filaments responsible for cell attachment. These tunable properties of very thin homopolymer PDEGMA brushes render this system interesting as an alternative thermoresponsive layer for continuous cell culture or enzyme‐free cell culture systems.

     

Aligned Poly(ε‐caprolactone) Nanofibers Guide the Orientation and Migration of Human Pluripotent Stem Cell‐Derived Neurons,Astrocytes, and Oligodendrocyte Precursor Cells In Vitro

Stem cell transplantations for spinal cord injury (SCI) have been studied extensively for the past decade in order to replace the damaged tissue with human pluripotent stem cell (hPSC)‐derived neural cells. Transplanted cells may, however, benefit from supporting and guiding structures or scaffolds in order to remain viable and integrate into the host tissue. Biomaterials can be used as supporting scaffolds, as they mimic the characteristics of the natural cellular environment. In this study, hPSC‐derived neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) are cultured on aligned poly(ε‐caprolactone) nanofiber platforms, which guide cell orientation to resemble that of spinal cord in vivo. All cell types are shown to efficiently spread over the nanofiber platform and orient according to the fiber alignment. Human neurons and astrocytes require extracellular matrix molecule coating for the nanofibers, but OPCs grow on nanofibers without additional treatment. Furthermore, the nanofiber platform is combined with a 3D hydrogel scaffold with controlled thickness, and nanofiber‐mediated orientation of hPSC‐derived neurons is also demonstrated in a 3D environment. In this work, clinically relevant materials and substrates for nanofibers, fiber coatings, and hydrogel scaffolds are used and combined with cells suitable for developing functional cell grafts for SCI repair.

     

Synthesis and characterization of BaGa2O4 and Ba3Co2O6(CO3)0.6 compounds in the search of alternative materials for Proton Ceramic Fuel Cell (PCFC)

BaGa₂O₄ and Ba₃Co₂O₆(CO₃)_0.6 compounds were studied as electrolyte and cathode materials for Proton Ceramic Fuel Cells (PCFC), respectively. Not only BaGa₂O₄ rapidly reacts with atmospheric H₂O and CO₂ and leads to a progressive material decomposition, but it does not present real hydration properties in normal conditions of pressure. On the other hand, the basic cobalt oxocarbonate Ba₃Co₂O₆(CO₃)_0.6 exhibits an interesting tendency for weight uptake and formation of hydrogencarbonate groups in moist heating/cooling conditions. This material was therefore considered for complementary studies in order to confirm its potential use as mixed proton-electron conductor, taking into account the ordered intergrowth of carbonates and face sharing Co-octahedra columns forming a pseudo-one-dimensional structure. Some preliminary results concerning electrochemical properties of the barium cobalt oxocarbonate as a PCFC cathode are also described and show at the moment modest performance, possibly related to a hydrated/carbonated surface layer contribution and/or the lack of electron percolation within the electrode layer.     

Microfibers as Physiologically Relevant Platforms for Creation of 3D Cell Cultures

Microfibers have received much attention due to their promise for creating flexible and highly relevant tissue models for use in biomedical applications such as 3D cell culture, tissue modeling, and clinical treatments. A generated tissue or implanted material should mimic the natural microenvironment in terms of structural and mechanical properties as well as cell adhesion, differentiation, and growth rate. Therefore, the mechanical and biological properties of the fibers are of importance. This paper briefly introduces common fiber fabrication approaches, provides examples of polymers used in biomedical applications, and then reviews the methods applied to modify the mechanical and biological properties of fibers fabricated using different approaches for creating a highly controlled microenvironment for cell culturing. It is shown that microfibers are a highly tunable and versatile tool with great promise for creating 3D cell cultures with specific properties.     

不同聚合物分散剂对Pt/SAPO-11催化剂性能的影响

采用浸渍法制备了经过不同聚合物分散剂处理的Pt/SAPO-11催化剂,并通过X射线衍射(XRD)、透射电子显微镜(TEM)、N₂吸附-脱附和NH₃程序升温脱附(TPD)等对催化剂的组织结构进行了表征。结果表明,分散剂不会破坏催化剂的结构,反而提高了其孔体积、孔径和比表面积,同时改变了沸石的酸强度和酸量,其中以聚乙烯吡咯烷酮处理的Pt/SAPO-11催化剂孔体积、孔径和酸性分布最佳。在固定床反应器上对不同分散剂处理的Pt/SAPO-11催化剂催化性能进行评价,结果表明聚乙烯吡咯烷酮处理的Pt/SAPO-11催化剂也表现出最佳的催化性能,麻风树油的加氢脱氧率高达99.45%,生物航空煤油组分收率和异构烷烃组分(C₈~C₁₆)的选择性分别达到了44.67%和56.37%。     

Synthesis and cytotoxicity studies of new 1,2,4-thiadiazole derivatives and their zinc complexes

A new polyfunctional ligand of the thiadiazole family was synthesized. Cytotoxic properties with respect to leukemic cell lines, radiation stability, predicted permeability through the blood–brain barrier and cardiotoxicity of the new ligand and its precursor were determined. New zinc complexes with N-{2-[5-(3-chloro-4-methylphenylamino)-1,2,4-thiadiazol-3-yl]-1-methylethyl}-N-(2,2,6,6-tetramethylpiperidin-4-yl)-amine as the ligand have been obtained.     

Liquid interfacial nanoarchitectonics: Molecular machines,organic semiconductors,nanocarbons, stem cells,and others

The concept of nanoarchitectonics has been proposed as an extensional development of nanotechnology through fusions with material science and the other fields. In nanoarchitectonics, nano-units of atoms, molecules, and nanomaterials are architected into construction of functional material systems. In order to assemble intended structures or hierarchical structures from nano-units, it is more useful to confine nano-units at the interface. In addition, nanoarchitectonics is expected to output functions by harmonizing many units in dynamic environments. However, the liquid interfaces still have lots of unexplored matters in nanoscale because supports by advanced apparatus and techniques in nanotechnology are not always available. Specifically, this review paper summarizes examples of research on molecular manipulation, molecular arrangement and assembly, materials synthesis, and life manipulation at the liquid interface. These examples demonstrate that the liquid interface enables the control of dynamic functions of various size regions, from molecular-level phenomena such as the control of molecular machines to techniques of living creature size such as the control of stem cell differentiation. Liquid interfaces are very useful environments for controlling dynamic functions for a wide range of targets and would have tremendous potential in terms of functional exploration. The great potential of nanoarchitectonics at the liquid interface and the challenges to be solved in the future are also discussed.     

Instantaneous Free Radical Scavenging by CeO2 Nanoparticles Adjacent to the Fe−N4 Active Sites for Durable Fuel Cells

To achieve the Fe−N−C materials with both high activity and durability in proton exchange membrane fuel cells, the attack of free radicals on Fe−N₄ sites must be overcome. Herein, we report a strategy to effectively eliminate radicals at the source to mitigate the degradation by anchoring CeO₂ nanoparticles as radicals scavengers adjacent (Sca^ad-CeO2) to the Fe−N₄ sites. Radicals such as ⋅OH and HO₂⋅ that form at Fe−N₄ sites can be instantaneously eliminated by adjacent CeO₂, which shortens the survival time of radicals and the regional space of their damage. As a result, the CeO₂ scavengers in Fe−NC/Sca^ad-CeO2 achieved ∼80 % elimination of the radicals generated at the Fe−N₄ sites. A fuel cell prepared with the Fe−NC/Sca^ad-CeO2 showed a smaller peak power density decay after 30,000 cycles determined with US DOE PGM-relevant AST, increasing the decay of Fe−NC_Phen from 69 % to 28 % decay.     

Aggregation-induced Emission Materials for High-efficiency Perovskite Solar Cells

The perovskite solar cells (PSCs) with high efficiency and stability are in great demand for commercial applications. Although the remarkable photovoltaic feature of perovskite layer plays a great role in improving the PCE of PSCs, the inevitable defects and poor stability of perovskite, etc. are the bottleneck and restrict the commercialization of PSCs. Herein, a review provides a strategy of applying aggregation-induced emission (AIE) molecules, containing passivation functional groups and distinct AIE character, which serves as the alternative materials for fabricating high-efficiency and high-stability PSCs. The methods of introducing AIE molecules to PSCs are also summarized, including additive engineering, interfacial engineering, hole transport materials and so on. In addition, the functions of AIE molecule are discussed, such as defects passivation, morphology modulation, well-matched energy level, enhanced stability, hole transport ability, carrier recombination suppression. Finally, the detailed functions of AIE molecules are offered and further research trend for high performance PSCs based on AIE materials is proposed.