The effect of electrode porosity on the electrochemical response of redox active molecules (potassium ferricyanide, ruthenium(III) hexammine, and ferrocene methanol) in the presence of bovine serum albumin or fibrinogen was studied at macroporous (pore diameter: 1200 nm), hierarchical (1200/60 nm), and nanoporous (<50 nm) gold. These electrodes were prepared using standard templating or dealloying techniques, and cyclic voltammetry (CV) was utilized to evaluate the effect of protein adsorption on the electron transfer of the diffusing redox probes. Following exposure to albumin (or fibrinogen) under near neutral pH conditions, planar gold electrodes showed an immediate reduction in Faradaic peak current and increase in peak splitting for potassium ferricyanide. The rate at which the CV curves changed was highly dependent on the morphology of the electrode. For example, the time required for the Faradaic current to drop to one-half of its original value was 3, 12, and 38 min for planar gold, macroporous gold, and hierarchical gold, respectively. Remarkably, for nanoporous gold, only a few percent drop in the peak Faradaic current was observed after an hour in solution. A similar suppression in the voltammetry at planar gold was also noted for ruthenium hexammine at pH 3 after exposure to albumin for several hours. At nanoporous gold, no significant loss in response was observed. The order of performance of the electrodes as judged by their ability to efficiently transfer electrons in the presence of biofouling agents tracked porosity with the electrode having the smallest pore size and largest surface area, providing near ideal results. Nanoporous gold electrodes when immersed in serum or heparinized blood containing potassium ferricyanide showed ideal voltammetry while significant fouling was evident in the electrochemical response at planar gold. The small nanopores in this 3D open framework are believed to restrict the transport of large biomolecules, thus minimizing passivation of the inner surfaces while permitting access to small redox probes to efficiently exchange electrons.

Assembly of lightweight engineering and functional materials with superb mechanical performance, such as high stiffness, super resilience, and stability, is highly demanded to pave ways for their practical applications. [1] However, how to simultaneously achieve both stiffness and resilience in a man-made material at low-density remains a challenging scientific and engineering issue. Biological materials have found their way to achieve outstanding mechanical properties at low density by assembling sophisticate hierarchical structures from microscopic to macroscopic scales, and thus provide inspirations for designing and manufacturing advanced biomimetic materials. [2] Plant materials, such as plant stem [3] and wood, [4] represent an important class of lightweight natural materials with superb mechanical properties. The slender grass stems of Elytrigia repens is a representative natural material with high mechanical performance and lightweight features owing to a specially evolved hierarchical architecture with a macroscopically hollow and microscopically cellular structure. The macroscopically hollow structure combined with the cellular microstructure serves as an excellent force-bearing structure that is conducive to the dispersion of strain and stress, and thus efficiently enhances the stiffness, and resilience and reduce the density, simultaneously. [5] In recent years, the constructions of biomimetic structures have attracted extensive attention because of their potential ability to achieve high mechanical properties and lightweight artificial engineering and functional materials. [6] Despite progresses in the construction of biomimetic structures, the poor mechanical properties at low density remain as a major bottleneck in artificial biomimetic materials, which are mainly due to the lack of appropriate structures at both macro-and microlevels at the same time.The ink-based 3D printing, as a powerful additive manufacturing technique for producing 3D structures both in microscopic and macroscopic scales, [6b,7] shows great potential to assembly materials into 3D hierarchical structures. Additionally, 3D printing displays distinct advantages of high degree of freedom in structure design, which enable the ability to design and construct versatile structures for realizing the Biological materials with hierarchical architectures (e.g., a macroscopic hollow structure and a microscopic cellular structure) offer unique inspiration for designing and manufacturing advanced biomimetic materials with outstanding mechanical performance and low density. Most conventional biomimetic materials only benefit from bioinspired architecture at a single length scale (e.g., microscopic material structure), which largely limits the mechanical performance of the resulting materials. There exists great potential to maxime the mechanical performance of biomimetic materials by leveraging a bioinspired hierarchical structure. An ink-based three-dimensional (3D) printing strategy to manufacture an ultralight biomimetic hierarchical g...

Electronegative guests filled into CoSb3yield a unique “cluster vibration” that provides a new perspective on designing novel inclusion compounds.

No abstract

Recently, it has been theoretically predicted that Cd3As2 is a three dimensional Dirac material, a new topological phase discovered after topological insulators, which exhibits a linear energy dispersion in the bulk with massless Dirac fermions. Here, we report on the low-temperature magnetoresistance measurements on a ~50 nm-thick Cd3As2 film. The weak antilocalization under perpendicular magnetic field is discussed based on the two-dimensional Hikami-Larkin-Nagaoka (HLN) theory. The electron-electron interaction is addressed as the source of the dephasing based on the temperature-dependent scaling behavior. The weak antilocalization can be also observed while the magnetic field is parallel to the electric field due to the strong interaction between the different conductance channels in this quasi-two-dimensional film.

Hierarchical templates with raspberry-like and strawberry-like features were prepared by synthetically joining appropriately functionalized commercially available polystyrene (PS) latex spheres together. Two different coupling reactions were used to form the hierarchical templates: carbodiimideassisted coupling of COOH groups with NH 2 groups and base-assisted coupling of epoxy groups with NH 2 groups. Since the templates are made by chemically bonding PS spheres together, both the "core" and "satellite" spheres can be different sizes. In this work, hierarchical spheres with core/satellite diameters of 1500/110 nm, 450/80 nm, 340/29 nm, and 1200/29 nm were made. The spheres were isolated and then used as hierarchical templates to prepare porous materials with well-defined architecture. Multimodal porous silica and bimodal macroporous gold electrodes were fabricated using the 1500/110 nm hierarchical template. Because the templates were constructed of only one material, polystyrene, they were easily removed from the host material to yield the macroporous material with pores of well-defined sizes that corresponded to the size of the template. It is envisioned that these hierarchical porous supports will be useful in chemical sensing and other applications that require large open pores to minimize diffusion restraints and smaller pores to increase surface area.

Enhancing the transport contribution of surface states in topological insulators is vital if they are to be incorporated into practical devices. Such efforts have been limited by the defect behaviour of Bi2Te3 (Se3) topological materials, where the subtle bulk carrier from intrinsic defects is dominant over the surface electrons. Compensating such defect carriers is unexpectedly achieved in (Cu0.1Bi0.9)2Te3.06 crystals. Here we report the suppression of the bulk conductance of the material by four orders of magnitude by intense ageing. The weak antilocalization analysis, Shubnikov–de Haas oscillations and scanning tunnelling spectroscopy corroborate the transport of the topological surface states. Scanning tunnelling microscopy reveals that Cu atoms are initially inside the quintuple layers and migrate to the layer gaps to form Cu clusters during the ageing. In combination with first-principles calculations, an atomic tunnelling–clustering picture across a diffusion barrier of 0.57 eV is proposed.

Inorganic materials combining photochromism and luminescence modulation characteristics have great potential in dual‐mode rewritable optical storage due to their unique optical features and excellent thermal stability. However, the failure of achieving a large luminescence modulation and a strong photochromic efficiency in photostimulated inorganic photochromic materials limits their applications. Herein, a new strategy for realizing an overlap between the photochromic absorption peak and the photoluminescent emission/excitation peak is proposed for designing high‐performance photochromic materials. The obtained BaMgSiO4: M (M = Ce3+, Mn2+, or Nd3+) ceramics exhibit a reversible white‐pink color change upon alternate 310 nm and 590 nm illumination (or thermal stimulus) accompanied by a high photochromic efficiency (>50%). Benefiting from a perfectly matched photochromic absorption peak and Mn2+ emission peak, a record luminescence modulation of 96.3% with excellent fatigue resistance is obtained in BaMgSiO4: Mn2+ ceramics. These properties are superior to all photochromic materials reported to date, demonstrating great potential in optical information storage applications. The trap‐related photochromic and regulated luminescence behavior is investigated together with a prototype of a dual‐mode information display. This work is expected to promote the practical application of photochromic materials in various optical devices and provides an effective strategy to develop other photochromic materials.