In a previous study we had shown that membrane cholesterol removal induced unregulated lysosomal exocytosis events leading to the depletion of lysosomes located at cell periphery. However, the mechanism by which cholesterol triggered these exocytic events had not been uncovered. In this study we investigated the importance of cholesterol in controlling mechanical properties of cells and its connection with lysosomal exocytosis. Tether extraction with optical tweezers and defocusing microscopy were used to assess cell dynamics in mouse fibroblasts. These assays showed that bending modulus and surface tension increased when cholesterol was extracted from fibroblasts plasma membrane upon incubation with MβCD, and that the membrane-cytoskeleton relaxation time increased at the beginning of MβCD treatment and decreased at the end. We also showed for the first time that the amplitude of membrane-cytoskeleton fluctuation decreased during cholesterol sequestration, showing that these cells become stiffer. These changes in membrane dynamics involved not only rearrangement of the actin cytoskeleton, but also de novo actin polymerization and stress fiber formation through Rho activation. We found that these mechanical changes observed after cholesterol sequestration were involved in triggering lysosomal exocytosis. Exocytosis occurred even in the absence of the lysosomal calcium sensor synaptotagmin VII, and was associated with actin polymerization induced by MβCD. Notably, exocytosis triggered by cholesterol removal led to the secretion of a unique population of lysosomes, different from the pool mobilized by actin depolymerizing drugs such as Latrunculin-A. These data support the existence of at least two different pools of lysosomes with different exocytosis dynamics, one of which is directly mobilized for plasma membrane fusion after cholesterol removal.

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Supercapacitor electrodes consisting of conjugated polymers (CP), metal oxides and graphene nanosheets have been explored as a strategy to achieve high specific capacitance, power, energy density, and stability. In this work, we synthesized a 3D structure composed of zirconia oxide nanoparticles (ZrO 2), reduced graphene oxide (rGO) and polypyrrole (PPy), using a simple and easily scalable one-step chronoamperometry method. Detailed characterization revealed that the addition of rGO and ZrO 2 modified the morphology of the electrode material. The capacitance of the resulting architecture improved by up to a 100%. The ternary composite featured high stability, with an increase of 5% in capacitance after a thousand cycles. DFT and MD simulations were carried out in order to provide further insight on the role of zirconia.

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Some sub-products from the industrial activity are rich in metals, very often being highly toxic to human health and to the environment. Thus, the development of real-time and ultrasensitive techniques for metals detection is relevant. Herein, we report an ion-sensitive field-effect transistor (ISFET) based on l-phenylalanine functionalized graphene that detects Na+, Co2+, and Al3+ at the nanomolar range and Cu2+ at the picomolar range. Our sensor is prepared using a simple functionalization method and is reusable after a standard HCl cleaning process. Altogether, the ISFET is a promising device for real-time detection of metal ions at low concentrations.

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COMMUNICATION (1 of 7)the energy requirements of the world. However, with the increase of population and development of technology, fossil fuels cannot serve as the primary energy source in the future due to the shortage of energy resources and a series of environment problems. As a result, renewable energy sources and their storage are becoming increasingly important. To solve this energy demand, it is necessary to develop new systems to improve the efficiency of energy conversion and storage. Development and design of new high-performance materials are the state-of-the-art of these systems. To improve them, new nonexpensive and efficient materials, such as metal sulfides, [1][2][3][4] carbides, [5][6][7][8] nitrides, [9,10] and phosphides, [11][12][13] have been explored. High-temperature stable (>1000 °C) transition metal carbides have great potential especially for catalysis and energy storage application due to their structural stability and high chemical activity. [5,[14][15][16][17][18] Recent reports have shown that metal carbides can replace classical expensive metal catalysts such as platinum. [19][20][21] Among all metal carbides, molybdenum carbide (Mo 2 C) possesses numerous valuable properties, particularly of excellent catalytic properties, such as high electronic conductivity as well as excellent thermal, mechanical, and chemical stability. [22] There are several material properties that play an important role on the efficiency of the catalyst such as the surface area, morphology, and the structure that can strongly affect its catalytic activity. For example, Tuomi et al. reported that the catalytic activity of molybdenum carbide is highly affected by the surface orientation. [23,24] In addition, molybdenum carbide-derived materials have also been studied in electrochemical applications such as Li-ion batteries and supercapacitors, due to its high theoretical capacity and capacitance. [22,[25][26][27] Recently, there has been much interest for creating origamilike structures in natural sciences, engineering, and architecture. Across these different fields, origami starts to inspire researchers for new reconfigurable and multifunctional materials and structures. However, the use of origami designs at the nanoscale is typically compromised by limitations in structural performance. If nanomaterials can be created in origami-like shapes, new multifunctional materials with improved surface area, mechanical properties, and performance in devices can be fabricated. Although metal carbides have exciting properties, High-temperature stable transition metal carbides are one of the promising classes of materials for next-generation energy applications such as water splitting catalysis and electrodes for energy storage devices. Herein, origami-like molybdenum carbide flakes with interfacially connected structures in various orientations using an easily scalable chemical vapor deposition method are synthesized. Interestingly, each individual flake of similar orientation is interconnected across different plane...