Current Nanoscience - Volume 11, Issue 6, 2015

Mesoscopic solar cell is a class of third-generation solar devices. A striking characteristic of mesoscopic solar cell is that the fabrication of the absorber layer can be conducted by solution-based approach; this non-vacuum processing renders significant reduction of the fabrication cost. In this article, we will review the recent development of light absorbing materials for mesoscopic sensitized solar cells. We will focus on the state-of-the-art development of dye molecules, inorganic semiconducting quantum dots, and organic-inorganic perovskite materials. We will also summarize some innovative sensitization methods in the device fabrication for the improvement of light absorptions. Finally, we will highlight some unique properties of each sensitizer and make a comprehensive comparison.

Recent advances in fluorescent noble metal nanoclusters, e.g. Au and Ag, have prompted the development of fluorescent film sensors. These metal nanoclusters possess the unique and intriguing physical and chemical properties including strong photoluminescence and excellent photostability. Up to date, a wide variety of organic ligands have been used for the synthesis of the nanoclusters. These organic ligands not only provide versatile connecting antennae for facile immobilization of the nanoclusters for fabricating fluorescent film sensors, but also facilitate the interaction of the encapsulated nanoclusters with the analytes, leading to improved sensor performance. The present review shows the recent progress in the fabrication and applications of fluorescent film sensors based on Au and Ag nanoclusters.

Electrospinning is a simple, quick, inexpensive and effective technique to produce continuous nanofibers (NFs) that are widely used in many research areas. This review focuses on the recent development of electrospun NFs-based electrochemical sensors. The preparation processes and characterization methods of electrochemical sensors are briefly introduced. The most relevant applications of electrochemical sensors on the detection of biomolecules using bare electrodes or NFs-based electrodes are thoroughly discussed. The main strengths and weaknesses of NFs-based electrochemical sensors are critically evaluated. The potential development and applications of the electrospun NFs-based electrochemical sensors are also discussed.

Living systems have evolved a variety of complex nanostructures to control biomolecular interactions and biochemical reactions that are vital to the metabolism and reproduction. During the past few decades, single-molecule detection and imaging have been widely applied to interpreting biological processes in detail, which are able to observe the chemical reactions and kinetic behaviors of individual molecules. The rapid development of structural DNA nanotechnology has provided adaptable platforms to facilitate single-molecule detection and super-resolution imaging of individual biological components, as well as manipulating artificial nanosystems with molecular precision. In this review, we summarize recent exciting progress in using DNA nanostructures to sense and manipulate biomolecular interactions at the single-molecule level.

This overview focuses on the study of non-enzymatic electrochemical glucose sensing over the last decade. The electrocatalytic performances and mechanisms of glucose oxidation using a variety of nanostructured materials are discussed, particularly for metallic nanomaterials. The history and limitations of enzymatic sensors are also introduced in this review.

Recent industrial and urban activities have led to elevated concentrations of a wide range of contaminants in water and soil, which affect the health of millions of people worldwide. This review reports some recent advances in the use of zero-valent iron nanoparticles (ZVINPs) for environmental remediation. Various solid materials such as carbon, silica, oxides, and clay minerals, as well as flexible materials such as polymer, membranes and nanofibers have been used to stabilize or support the formation of ZVINPs. The used supporting materials are able to significantly improve the stability of the ZVINPs, to improve the accessibility of ZVINPs to hydrophobic organic pollutants, and to eliminate the oxidation of Fe0. Some of the key developments in the formation of various ZVINP-based composite materials for the remediation of dyeing wastewater, chlorinated organic compounds, heavy metal irons, etc. will be introduced and discussed in detail.

In crowded public areas (hospitals, airports, railway stations, universities, schools, etc.), surfaces of the materials are exposed to microorganisms. These microorganisms can live both in planktonic and biofilm (colonies of microorganisms) being responsible for the transmission of different infections from human to human. Because of that, the antimicrobial effect is an additional function of film-forming materials. The innovation of these types of materials consists both in choosing and stabilizing the active substance in the polymeric material and in the microbial control. Usage of the AgNPs as active substance induces morphological changes in the structure of the film-forming material, a chemical resistance and an antimicrobial efficacy for a long time. The antimicrobial properties of the new materials reduce the consumption of disinfectants and the number of washing cycles which implicitly leads to reduced maintenance costs. The influence of the AgNPs on the morphology, structure and properties of the material coatings was investigated by EDX, SEM and SPM. The antifungal activity of the film-forming materials was investigated onto 12 cultures of mushrooms. Silver nanoparticles can prevent the formation of biofilms through the killing of the fungus and of the bacteria (both gram-positive and gram-negative) that are present on the surface of materials. Materials coatings were applied in a medical unit and after 12 months from application, it was found that neither morphology or structure nor the antifungal or the antibacterial properties have undergone significant changes. Based on these results it is considered that the film-forming materials based on silver nanoparticles could be used to inhibit the development of micro-organisms on concrete surfaces or plasterboard inside the medical units for long time.

In this paper we improve the semi-empirical compact model for CNTFETs, already proposed by us, considering both the quantum capacitance effects and the sub-threshold currents in order to carry out dynamic analysis of basic digital circuits. To verify the validity of the obtained results, they are compared with those of Wong model. Our model may be easily implemented both in SPICE and in Verilog-A, obtaining, in this last case, the development time in writing the model shorter, the simulation run time much shorter and the software much more concise and clear than Wong model.

A composite picture of multi-wall carbon nanotubes (MWCNTs) with Nafion (NF) cation exchange membrane is prepared by cast deposition on glassy carbon electrodes. A sensitive electrochemical sensor for the detection of bilirubin (BR) at the NF/MWCNTs hybrid modified glassy carbon electrode was offered. The electrochemical behaviors of bilirubin at the NF/MWCNTs hybrid electrode were studied in acetone containing sulfuric acid as the supporting electrolyte. Compared with bare glassy carbon electrode (GCE), the proposed integrated sensor, improved analytical performance characteristics in the electrochemical oxidation of bilirubin. The electrochemistry of bilirubin on NF/MWCNTs hybrid electrodes were studied by electrochemical impedance spectroscopy, cyclic voltammetry (CV) and square-wave voltammetry (SWV). The oxidation peak current of bilirubin obtained at the NF/MWCNTs modified GC electrode was 10 times higher than that of the unmodified glassy carbon electrode. To optimize the experimental conditions, a linear calibration plot for bilirubin was obtained between 0.8 μM and 10 μM with the detection limit of 0.014 μM. Finally, the proposed sensor was successfully employed to determine bilirubin in human urine samples.

Protons irradiation induced coalescence between two silver nanowires (Ag-NWs) was investigated using scanning and transmission electron microscopy (SEM and TEM). The coalescence process was found to proceed via proton beam induced local heating and collision cascade of atomic displacement mechanism, imposing a continuous restructuring of Ag atoms in individual NW lattices along adjacent NWs leading to the merging of two Ag-NWs together. Evidence of amorphization or crystal structure damage of the Ag-NWs under proton irradiation was not observed in the x-ray diffraction (XRD) analysis. This work may potentially be used for developing complex metal nanowire networks.

Associative memory, considered as the ability to link unrelated objects, is the most appealing behaviour found in both biological and artificial neural networks. Here we for the first time proposed a three terminal phase-change based nanoscale device where associative memory can be theoretically achieved according to the developed electro-thermal model. Compared with the conventional neural networks circuit, the designed device allows for an exemption from a large number of circuit elements, and thus exhibits an exciting potential for ultra-high integration density and super-fast response speed. The simulation results opens up a novel route to imitate the complex mechanism of the biological neural networks, thus rendering phase-change materials a promising contender for the key components in next-generation neuromorphic system.

In spite of zinc oxide nanoparticles proved good adsorbent for dyes, however, its agglomeration tendency in aqueous media, that corresponding to its hydrophobic nature declines its efficiency. Consequently, the prepared zinc oxide nanoparticles were encapsulated onto a polymer blend of alginate and polyvinyl alcohol to be formulated into bio-beads of zinc oxide. The produced bio-beads were characterized using SEM and XRD. The feasibility of the formulated bio-composite beads for C.I basic blue 41 (CB41) decolorization from aqueous solution was evaluated using batch technique. The experimental results at equilibrium were analyzed using different isotherm models to evaluate the equilibrium adsorption behavior of CB41 onto the prepared materials. It was indicated that, the equilibrium sorption data was fitted well by Freundlich, and Dubinin-Radushkevich isotherms compared to Langmuir and Temkin isotherms. Kinetic profile of the dye sorption process evident from the film diffusion of dyes on to hybrid beads controls the rate of process.