The development of rapid, specific, cost-effective, and robust tools in monitoring Hg(2+) levels in both environmental and biological samples is of utmost importance due to the severe mercury toxicity to humans. A number of techniques exist, but the colorimetric assay, which is reviewed herein, is shown to be a possible tool in monitoring the level of mercury. These assays allow transforming target sensing events into color changes, which have applicable potential for in-the-field application through naked-eye detection. Specifically, plasmonic nanoparticle-based colorimetric assay exhibits a much better propensity for identifying various targets in terms of sensitivity, solubility, and stability compared to commonly used organic chromophores. In this review, recent progress in the development of gold nanoparticle-based colorimetric assays for Hg(2+) is summarized, with a particular emphasis on examples of functionalized gold nanoparticle systems with oligonucleotides, oligopeptides, and functional molecules. Besides highlighting the current design principle for plasmonic nanoparticle-based colorimetric probes, the discussions on challenges and the prospect of next-generation probes for in-the-field applications are also presented.

Large‐area graphene nanomesh (GNM) is prepared using a new and effective method, in which the O2 plasma treatment is used with an anodic aluminum oxide (AAO) membrane as an etch mask. By varying the pore size and cell wall thickness of the AAO membrane, GNM with tunable pore size and neck width can be prepared. As proof of concept, a field‐effect transistor with 15 nm neck width GNM as the conductive channel is fabricated, which exhibits p‐type semiconducting behavior.

Although theoretical calculations indicate that the thermoelectric figure of merit, ZT, of carbon nanotubes (CNTs) could reach >2, the experimentally reported ZT values of CNTs are typically in the range of 10 À3 -10 À2 , which is not attractive for thermal energy conversion applications. In this work, we report the preparation of flexible CNT bulky paper for thermoelectric applications. The ZT values of the CNT bulky papers could be significantly enhanced by Ar plasma treatment, i.e. increasing it from 0.01 for pristine CNTs to 0.4 for Ar-plasma treated CNTs. The improved thermoelectric properties were mainly due to the greatly increased Seebeck coefficients and a reduction in the thermal conductivities, although the electrical conductivities also decreased. Such an improvement makes the plasma treated CNT bulky papers promising as a new type of thermoelectric material for certain niche applications as they are easily processed, mechanically flexible and durable, and chemically stable.

p-type Bi0.4Sb1.6Te3 nanocomposites with enhanced figure of merit

A controllable and reproducible bipolar memristive protein nanodevice is fabricated by chemical immobilization of ferritin molecules within on‐wire lithography‐generated nanogaps. Control experiments suggest that programmable resistive switching is due to the electrochemical processes in the active centre of ferritin. Such ferritin‐based nanodevices with reversible resistance can be used for nonvolatile memory based on write‐read‐erase cycles.