Maneuvering the mineralization of self-assembled peptide nanofibers for designing mechanically-stiffened self-healable composites toward bone-mimetic ECM.

Extracellular matrix (ECM) elasticity remains a crucial parameter to determine cell-material interactions (viz. adhesion, growth, and differentiation), cellular communication, and migration that are essential to tissue repair and regeneration. Supramolecular peptide hydrogels with their 3-dimensional porous network and tuneable mechanical properties have emerged as an excellent class of ECM-mimetic biomaterials with relevant dynamic attributes and bioactivity. Here, we demonstrate the design of minimalist amyloid-inspired peptide amphiphiles, CnPA (n = 6, 8, 10, 12) with tuneable peptide nanostructures that are efficiently biomineralized and cross-linked using bioactive silicates. Such hydrogel composites, CnBG exhibit excellent mechanical attributes and possess excellent self-healing abilities and collagen-like strain-stiffening ability as desired for bone ECM mimetic scaffold. The composites exhibited the formation of a hydroxyapatite mineral phase upon incubation in a simulated body fluid that rendered mechanical stiffness akin to the hydroxyapatite-bridged collagen fibers to match the bone tissue elasticity eventually. In a nutshell, peptide nanostructure-guided temporal effects and mechanical attributes demonstrate C8BG to be an optimal composite. Finally, such constructs feature the potential for adhesion, proliferation of U2OS cells, high alkaline phosphatase activity, and osteoconductivity.

Origin of discrete resistive switching in chemically heterogeneous vanadium oxide crystals.

Phase changes in oxide materials such as VO2 offer a foundational platform for designing novel solid-state devices. Tuning the V : O stoichiometry offers a vast electronic phase space with non-trivial collective properties. Here, we report the observation of discrete threshold switching voltages (Vth) with constant ΔVth between cycles in vanadium oxide crystals. The observed threshold fields over 10 000 cycles are ∼100× lower than that noted for stoichiometric VO2 and show unique discrete behaviour with constant ΔVth. We correlate the observed discrete memristor behaviour with the valence change mechanism and fluctuations in the chemical composition of spatially distributed VO2-VnO2n-1 complex oxide phases that can synergistically co-operate with the insulator-metal transition resulting in sharp current jumps. The design of chemical heterogeneity in oxide crystals, therefore, offers an intriguing path to realizing low-energy neuromorphic devices.

Substrate Versatile Roller Ball Pen Writing of Nanoporous MoS2 for Energy Storage Devices.

Low-cost fabrication of customizable supercapacitors and batteries to power up portable electronic devices is a much-needed step in advancing energy storage devices. The processing methods and techniques involved in developing small-sized entities in complex patterns are expensive, tedious, and time-consuming. Here, we demonstrate the fabrication of customizable electrochemical supercapacitors and batteries by simply employing the universal and conventional paradigm of direct pen writing with hands and evaluating their energy storage performance. The fabrication technique involves the refilling of MoS2 ink into the pen and then scripting of MoS2 nanostructures onto various substrates. The electrode material employed here consists of nanoporous microspheres of MoS2 synthesized by a simple one-step hydrothermal method. Direct pen writing with porous MoS2 in complex patterns enables easy, affordable, and simple fabrication of energy storage devices as and when required based on user choice toward distributed manufacturing and sustainability.

Porosity-Engineered CNT-MoS2 Hybrid Nanostructures for Bipolar Supercapacitor Applications.

Bipolar supercapacitors that can store many fold higher capacitance in negative voltage compared to positive voltage are of great importance if they can be engineered for practical applications. The electrode material encompassing high surface area, better electrochemical stability, high conductivity, moderate distribution of pore size, and their interaction with suitable electrolytes is imperative to enable bipolar supercapacitor performance. Apropos of the aforementioned aspects, the intent of this work is to ascertain the effect of ionic properties of different electrolytes on the electrochemical properties and performance of a porous CNT-MoS2 hybrid microstructure toward bipolar supercapacitor applications. The electrochemical assessment reveals that the CNT-MoS2 hybrid electrode exhibited a two- to threefold higher areal capacitance value of 122.3 mF cm-2 at 100 µA cm-2 in 1 M aqueous Na2SO4 and 42.13 mF cm-2 at 0.30 mA cm-2 in PVA-Na2SO4 gel electrolyte in the negative potential window in comparison to the positive potential window. The CNT-MoS2 hybrid demonstrates a splendid Coulombic efficiency of ∼102.5% and outstanding stability with capacitance retention showing a change from 100% to ∼180% over 7000 repeated charging-discharging cycles.

Arresting the surface oxidation kinetics of bilayer 1T'-MoTe2by sulphur passivation.

MoTe2garnered much attention among 2D materials due to stable polymorphs with distinctive structural and electronic properties. Among the polymorphs, 1T'-MoTe2in bulk form is type-II Weyl semimetal while, in monolayer form is a quantum spin Hall insulator. Thus, it is suitable for a wide variety of applications. Nevertheless, 1T'-MoTe2degrades within a few hours when exposed to the atmosphere and causes hindrances in device fabrication. Here the degradation kinetics of CVD-synthesized 1T'-MoTe2was investigated using Raman spectroscopy, XPS, and microscopic characterizations. The degradation rate of as-grown 1T'-MoTe2obtained was 9.2 × 10-3min-1. Further, we prevented the degradation of 1T'-MoTe2by introducing a thin coating of S that encapsulates the flakes. 1T'-MoTe2flakes showed stability for several days when covered using sulphur, indicating 25 times enhanced structural stability.