Fabrication of immunosensor microwell arrays from gold compact discs for detection of cancer biomarker proteins

A simple method is reported to fabricate gold arrays featuring microwells surrounding 8-electrodes from gold compact discs (CDs) for less than $0.2 per chip. Integration of these disposable gold CD array chips with microfluidics provided inexpensive immunoarrays that were used to measure a cancer biomarker protein quickly at high sensitivity. The gold CD sensor arrays were fabricated using thermal transfer of laserjet toner from a computer-printed pattern followed by selective chemical etching. Sensor elements had an electrochemically addressable surface area of 0.42 mm(2) with RSD <2%. For a proof-of-concept application, the arrays were integrated into a simple microfluidic device for electrochemical detection of cancer biomarker interleukin-6 (IL-6) in diluted serum. Capture antibodies of IL-6 were chemically linked onto the electrode arrays and a sandwich immunoassay protocol was developed. A biotinylated detection antibody with polymerized horseradish peroxidase labels was used for signal amplification. The detection limit of IL-6 in diluted serum was remarkably low at 10 fg mL(-1) (385 aM) with a linear response with log of IL-6 concentration from 10 to 1300 fg mL(-1). These easily fabricated, ultrasensitive, microfluidic immunosensors should be readily adapted for sensitive detection of multiple biomarkers for cancer diagnostics.     

Regioselective ring expansion of 2,4-diiminoazetidines via cleavage of C-N and C(sp3)-H bonds: efficient construction of 2,3-dihydropyrimidinesulfonamides

A highly regioselective base-mediated ring expansion of 2,4-diiminoazetidines via cleavage of C-N and C(sp(3))-H bonds is achieved for the first time to afford efficiently 2,3-dihydropyrimidinesulfonamides. The mechanism of the ring expansion via tandem 4π electrocyclic ring-opening/1,5-H shift/6π electrocyclic ring-closing is well confirmed by the trapping experiments of two key intermediates and deuterium labeling studies.     

Microwave-mediated heat transport in a quantum dot attached to leads

The thermoelectric effect in a quantum dot (QD) attached to two leads in the presence of microwave fields is studied by using the Keldysh nonequilibrium Green function technique. When the microwave is applied only on the QD and in the linear response regime, the main peaks in the thermoelectric figure of merit and the thermopower are found to decrease, with the emergence of a set of photon-induced peaks. Under this condition the microwave field cannot generate heat current or electrical bias voltage. Surprisingly, when the microwave field is applied only to one (bright) lead and not to the other (dark) lead or the QD, heat flows mostly from the dark to the bright lead, almost irrespective of the direction of the thermal gradient. We attribute this effect to microwave-induced opening of additional transport channels below the Fermi energy. The microwave field can change both the magnitude and the sign of the electrical bias voltage induced by the temperature gradient.     

The initial value problem for some hyperbolic‐dispersive system

We consider the initial value problem for some nonlinear hyperbolic‐dispersive systems in one space dimension. Combining the classical energy method and the smoothing estimates for the Airy equation, we guarantee the time local well‐posedness for this system. We also discuss the extension of our results to more general hyperbolic‐dispersive system. Copyright © 2011 John Wiley & Sons, Ltd.     

Degree bounded matroids and submodular flows

We consider two related problems, the Minimum Bounded Degree Matroid Basis problem and the Minimum Bounded Degree Submodular Flow problem. The first problem is a generalization of the Minimum Bounded Degree Spanning Tree problem: We are given a matroid and a hypergraph on its ground set with lower and upper bounds f(e)≤g(e) for each hyperedge e. The task is to find a minimum cost basis which contains at least f(e) and at most g(e) elements from each hyperedge e. In the second problem we have a submodular flow problem, a lower bound f(v) and an upper bound g(v) for each node v, and the task is to find a minimum cost 0–1 submodular flow with the additional constraint that the sum of the incoming and outgoing flow at each node v is between f(v) and g(v). Both of these problems are NP-hard (even the feasibility problems are NP-complete), but we show that they can be approximated in the following sense. Let opt be the value of the optimal solution. For the first problem we give an algorithm that finds a basis B of cost no more than opt such that f(e)?2Δ+1≤|B∩e|≤g(e)+2Δ?1 for every hyperedge e, where Δ is the maximum degree of the hypergraph. If there are only upper bounds (or only lower bounds), then the violation can be decreased to Δ?1. For the second problem we can find a 0–1 submodular flow of cost at most opt where the sum of the incoming and outgoing flow at each node v is between f(v)?1 and g(v)+1. These results can be applied to obtain approximation algorithms for several combinatorial optimization problems with degree constraints, including the Minimum Crossing Spanning Tree problem, the Minimum Bounded Degree Spanning Tree Union problem, the Minimum Bounded Degree Directed Cut Cover problem, and the Minimum Bounded Degree Graph Orientation problem.     

Improved hydrothermal synthesis of MoS2 sheathed carbon nanotubes

MoS₂ sheathed carbon nanotubes have been successfully synthesized using a hydrothermal route under controlled conditions. The resultant material was studied by XRD, EDS, HRTEM, and Raman spectroscopy. Advantages of the preparation presented here compared to other methods are: a) lower reaction temperature, b) high yield of sheathed nanotubes including ends and full body, c) simple process with non-toxic materials, and d) no damage inflicted to nanotubes.     

Direct visualization of bactericidal action of cationic conjugated polyelectrolytes and oligomers

The bactericidal mechanisms of poly(phenylene ethynylene) (PPE)-based cationic conjugated polyelectrolytes (CPE) and oligo-phenylene ethynylenes (OPE) were investigated using electron/optical microscopy and small-angle X-ray scattering (SAXS). The ultrastructural analysis shows that polymeric PPE-Th can significantly remodel the bacterial outer membrane and/or the peptidoglycan layer, followed by the possible collapse of the bacterial cytoplasm membrane. In contrast, oligomeric end-only OPE (EO-OPE) possesses potent bacteriolysis activity, which efficiently disintegrates the bacterial cytoplasm membrane and induces the release of bacterial cell content. Using single giant vesicles and SAXS, we demonstrated that the membrane perturbation mechanism of EO-OPE against model bacterial membranes results from a 3D membrane phase transition or perturbation.     

Preparation of Magnetic Nanoparticles and Their Use for Immobilization of C-Terminally Lysine-Tagged <Emphasis Type="Italic">Bacillus</Emphasis> sp. TS-23 α-Amylase

The aim of this investigation was to synthesize the adipic acid-modified magnetic nanoparticles for the efficient immobilization of C-terminally lysine-tagged α-amylase (BACΔNC-Lys₇) from thermophilic Bacillus sp. strain TS-23. The carboxylated magnetic nanoparticles were prepared by the simple co-precipitation of Fe³⁺/Fe²⁺ in aqueous medium and then subsequently modified with adipic acid. Transmission electron microscopy micrographs showed that the carboxylated magnetic nanoparticles remained discrete and had no significant change in size after the binding of BACΔNC-Lys₇. Free enzyme was active in the temperature range of 45–70 °C and had an optimum of 60 °C, whereas the thermal stability of BACΔNC-Lys₇ was improved as a result of immobilization. The immobilized BACΔNC-Lys₇ could be recycled 20 times without a significant loss of the amylase activity and had a better stability during storage with respect to free enzyme. Taken together, the magnetic nanoparticles coated with this functional moiety can be a versatile platform for the effective manipulation of various kinds of engineered proteins.     

A New Piezochromic Fluorescence and Aggregation-Induced Emission Compound Containing Tetraphenylethylene and Triphenylamine Moieties with Morphology-alterable Property

A novel piezochromic fluorescent (PCF) compound with aggregation-induced emission (AIE) effect and morphology-alterable emission property was developed. The amorphous and crystalline aggregates were obtained, and their spectroscopic properties and morphological structures were reversibly and repeatedly exhibited upon pressing (fuming) or annealing. The piezochromic fluorescent nature was generated through crystalline-amorphous phase transformation. It was proposed that AIE compounds existing a twisted propeller-shaped conformation will exhibit PCF activity. The common relationship betweeen AIE and PCF established will guide researchers in identifying and synthesizing more piezochromic fluorescent materials.     

In vivo Monitoring of Organ-Selective Distribution of CdHgTe/SiO2 Nanoparticles in Mouse Model

CdHgTe/SiO₂ nanoparticles were prepared by SiO₂ capping on the surface of CdHgTe QDs. The characteristics, such as optical spectra, photostability, size and cell toxicity were investigated. The dynamic distribution of CdHgTe/SiO₂ nanoparticles was in vivo monitored by near infrared fluorescence imaging system. CdHgTe/SiO₂ nanoparticles acted as a novel fluorescence probe have a maximum fluorescence emission of 785 nm and high photo-stability. The hydrodynamic diameter of CdHgTe/SiO₂ nanoparticles could be adjusted to 122.3 nm. Compared to CdHgTe QDs, inhibitory effects of CdHgTe/SiO₂ nanoparticles on proliferation of HCT116 cells decreased to a certain extent. CdHgTe/SiO₂ nanoparticles had their specific dynamic distribution behavior, which provided new perspectives for bio-distribution of nanoparticles.