Self-powered photochemical cathode aptamer sensor based on ZnIn2S4 photoanode and Cu2O@Ag@Ag3PO4 photocathode for the sensitive detection of Hg2.

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn2S4 as the photoanode and Cu2O@Ag@Ag3PO4 as the sensing cathode is designed for the detection of Hg2+. An indium tin oxide (ITO) electrode modified with ZnIn2S4 was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn2S4 can generate photogenerated electrons well. The unique hydrangea structure of ZnIn2S4 can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu2O@Ag@Ag3PO4 with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn2S4 photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg2+ (1 mM-1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform.

Applications of Graphene in Five Senses, Nervous System, and Artificial Muscles.

Graphene remains of great interest in biomedical applications because of biocompatibility. Diseases relating to human senses interfere with life satisfaction and happiness. Therefore, the restoration by artificial organs or sensory devices may bring a bright future by the recovery of senses in patients. In this review, we update the most recent progress in graphene based sensors for mimicking human senses such as artificial retina for image sensors, artificial eardrums, gas sensors, chemical sensors, and tactile sensors. The brain-like processors are discussed based on conventional transistors as well as memristor related neuromorphic computing. The brain-machine interface is introduced for providing a single pathway. Besides, the artificial muscles based on graphene are summarized in the means of actuators in order to react to the physical world. Future opportunities remain for elevating the performances of human-like sensors and their clinical applications.

In(2)O(3) microbundles constructed with well-aligned single-crystalline nanorods: F127-directed self-assembly and enhanced gas sensing performance.

Hierarchical In(2)O(3) rod-like microbundles were fabricated via the Pluronic F127-(EO(106)PO(70)EO(106)-) assisted hydrothermal reaction followed by calcining the In(OH)(3) precursors. The results revealed that the In(2)O(3) microarchitectures were constructed with well-aligned one-dimensional (1D) single-crystalline nanorods with highly uniform morphologies and particular exposed facets. Structural analysis suggested that the In(2)O(3) nanorods were enclosed by {110} and {001} facets. The triblock copolymer acted as a structure-directing agent and played a key role in the formation of In(OH)(3) microbundles. The formation of the precursors In(OH)(3) microbundles was studied through contrastive experiments and computational simulation, which can be contributed to the soft-template-directed self-assembly mechanism. The gas sensing properties of the as-prepared In(2)O(3) microbundles were investigated. Compared to the samples prepared in the absence of F127, the In(2)O(3) microbundles exhibited a superior sensing performance toward 2-chloroethanol vapor, which can be explained by hierarchically ordered structures and exposed crystal surfaces.

Catanionic-surfactant-controlled morphosynthesis and gas-sensing properties of corundum-type In(2)O(3).

Metastable corundum-type In(2)O(3) hierarchical structures with various morphologies inherited InOOH nanostructures, which were generated via a catanionic-surfactant-assisted solvothermal process. The products were characterized in detail by x-ray powder diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and HRTEM. These superstructures were built from one-dimensional components. The one-dimensional preferential growth is explained in terms of the crystallographic features of InOOH. The effects of reaction parameters on the formation of nanostructures are also discussed. It is demonstrated that both laurylamine and oleic acid play an important role in the generation of InOOH hierarchical structures. Gas sensors composed of In(2)O(3) hierarchical nanostructures show a good response to toxic chlorophenol at 280 degrees C.

Synthesis of Starch-Stabilized Ag Nanoparticles and Hg Recognition in Aqueous Media.

The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg(2+), and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg(2+) ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg(2+) ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg(2+) ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg(2+) over other metal ions including Na(+), K(+), Ba(2+), Mg(2+), Ca(2+), Fe(3+), and Cd(2+). The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11671-009-9387-6) contains supplementary material, which is available to authorized users.

Synthesis, Optical Properties, and Photocatalytic Activity of One-Dimensional CdS@ZnS Core-Shell Nanocomposites.

One-dimensional (1D) CdS@ZnS core-shell nanocomposites were successfully synthesized via a two-step solvothermal method. Preformed CdS nanowires with a diameter of ca. 45 nm and a length up to several tens of micrometers were coated with a layer of ZnS shell by the reaction of zinc acetate and thiourea at 180 °C for 10 h. It was found that uniform ZnS shell was composed of ZnS nanoparticles with a diameter of ca. 4 nm, which anchored on the nanowires without any surface pretreatment. The 1D CdS@ZnS core-shell nanocomposites were confirmed by XRD, SEM, TEM, HR-TEM, ED, and EDS techniques. The optical properties and photocatalytic activities of the 1D CdS@ZnS core-shell nanocomposites towards methylene blue (MB) and 4-chlorophenol (4CP) under visible light (λ > 420 nm) were separately investigated. The results show that the ZnS shell can effectively passivate the surface electronic states of the CdS cores, which accounts for the enhanced photocatalytic activities of the 1D CdS@ZnS core-shell nanocomposites compared to that of the uncoated CdS nanowires.

Arrangement of tris(phthalocyaninato) gadolinium triple-decker complexes with multi-octyloxy groups on water surface.

A series of five carefully designed tris(phthalocyaninato) gadolinium triple-decker complexes [Pc(R)8]Gd[Pc(R')8]Gd[Pc(R'')8] (R=R'=R''=H; R=R'=H, R''=OC8H17; R=R''=H, R'=OC8H17; R=H, R'=R''=OC8H17; R=R'=R''=OC8H17) (1-5) were prepared and the film forming properties on water surface were systematically investigated. The limited mean molecular area obtained by pi-A isotherms revealed an "edge-on" conformation for all these compounds. UV-vis absorption spectra showed red-shifted Q bands, indicating the formation of J aggregates and effective intermolecular interaction in solid film. Phthalocyanine rings were found to take tilted orientation with respect to the normal of substrate according to the polarized absorption spectroscopic measurements. Low angle X-ray diffraction results provide direct evidence and therefore clearly clarify the point, for the first time, that unsymmetrical triple-decker molecules pack on the water surface with the unsubstituted phthalocyanine ring set close to the water surface and the substituted phthalocyanine ligand with octyloxy groups lies on the top.