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Synthesis and characteristics of magnetic gold nanoshells are investigated and discussed from the viewpoint of photothermal therapy (PTT). Morphological properties of thickness, roughness, surface coverage of the shell, the pore size and so on influence their optical properties and the magnetic properties controlling the conditions of synthesis and thermal treatment. NIR light-absorbing gold nanoshells are successfully fabricated on silica/Fe-Pt core-shell nanoparticles via the two-step seed-mediated growth method using a polymer layer of polyethylenimine (PEI) as an interlayer. The cationic polyelectrolyte PEI with high amine content binds to the negatively charged Fe-Pt nanoshell through electrostatic self-assembly to form a stabilizing polyelectrolyte layer, which is necessary to not only the deposition of Au nanoparticles but also the growth of the uniform gold shell. The surface modification using PEI polymers with lower molecular weight of the Fe-Pt nanoshell leads to the formation of a high-quality gold shell with a smooth and thin morphology being responsible to the appearance of a strong NIR absorption. The photothermal properties are obtained by NIR laser irradiation without any deformation of the nanoshells. [ABSTRACT FROM AUTHOR]

In order to measure the two-dimensional distribution of the thickness of a metal layer coated on a dielectric layer at a time, we propose to use a micro-lens array (MLA), instead of a conventional single plano-convex lens, by which lots of surface-plasmon-resonance (SPR) dip patterns could be observed from a modified Otto configuration. The individual micro lenses produce circular ring-shaped SPR dip patterns in reflection, which enable us to estimate the thickness of the metal with high sensitivity and precision with ease. A spatial resolution is determined by the size of each lens and is 300 μm in diameter. As a proof-of the principle experiment, we measured the thickness of a 50nm-thickness Au film with precision ±0.9 nm for an area of 2.7 mm×2.7 mm. A method for improving the spatial resolution further is discussed.

Although immunochromatograph using nanoparticles has some merits such as an ease of use and a quick response, it has some issues such as a poor sensitivity and a lack of quantitativity. To overcome the issues, we investigate a new immunoassay method using a magneto-optical (MO) effect based on nanoparticle technologies. Bismuth-substituted yttrium-iron garnet (Bi-YIG) is one of the candidates, which exhibits a large Faraday effect. To enhance the Faraday effect for highly sensitive MO immunoassay, surface plasmon resonance (SPR) effect is employed in the preset study. Au nanoparticles have an absorption peak based on the SPR effect in the wavelength range of 500-600 nm by optimizing their size and interparticle distance. We fabricate MO and plasmonic particles composed of a Bi-YIG particle as a core and Au nanoparticles deposited on the core. The clear SPR absorption and the MO enhancement are obtained in the composites with a larger amount of Au nanoparticles deposited on Bi-YIG particles. The enhancement of the Faraday rotation is observed in the range of 500-700 nm, corresponding to the wavelength range where the clear SPR absorption was observed. The Faraday rotation increases by 50% in maximum at around 550 nm of wavelength. [ABSTRACT FROM AUTHOR]

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The interests of many researchers are focused on detection of telomerase, because highly sensitive detection of telomerase enables us to detect many kinds of cancers in their early stage, and also gives us much important information about cell biology. In this study, a new method of telomerase detection using polymeric microspheres on surface plasmon resonance (SPR)-based sensors is proposed. The telomerase detection is done through highly sensitive detection of G4-DNA generated from elongation of telomere by telomerase. The microspheres posses two functions: DNA structure recognition and SPR signal amplification. Polymeric microspheres could amplify the signal due to the interaction with G4-DNA about 760-times through DNA structure recognition. The lowest detection limit of telomerase was increased 150-fold by using polymeric microspheres. This method enables the detection of telomerase that is extracted from less than 1 cell. The results suggest that this newly proposed assay is suitable for detection of telomerase activity due to the ultrahigh sensitivity. [ABSTRACT FROM AUTHOR]

In small molecule drug discovery, researchers must find specific binders that interact with a target protein and inhibit its function in connection with human diseases. It is of critical importance to know the binding mode of compounds interacting with a target protein to assure hit validation and optimization. Biophysical analysis is a powerful quantitative approach to evaluate the binding modes of such candidates. Since the level of sensitivity of biophysical analysis is suitable to quantitatively detect the binding of fragment compounds, and because of the remarkable success of compound libraries of small molecules, the development and adaptation of biophysical analysis for these applications is in great demand. Herein, we describe the technical developments of biophysical methods, especially thermodynamic and kinetic analysis, for the purpose of screenings which employ small molecules. In addition, we discuss the interaction mechanisms of small molecules to find hit compounds based on these biophysical analyses.

Anyone talks about the taste using different taste scale. Since how to feel the taste is different from one to other people, we sometimes lead to inconsistency when speaking about the taste of food. The present study aims at development of electronic tongue (taste sensor) and electronic nose (odor sensor). There are two important properties about the taste sensor. One, each sensor electrode (lipid/polymer membrane) is specific to each taste. Another is that the sensor can measure the aftertaste such as richness, which is the aftertaste of umami. In the case of, e.g., bitterness electrode (BT0), it responds well to bitter taste substances such as quinine, cetirizine, hydroxyzine and bromhexine. For other taste qualities, on the other hand, it shows no response. A taste sensor is now sold by Intelligent Sensor Technology, Inc., and utilized in pharmaceutical and food companies. An electronic nose to detect lingering scent is composed of surface plasmon resonance (SPR) sensor, which is a sensing device with high sensitivity, and antigen-antibody interaction. A self-assembled monolayer was constructed on the reception surface of SPR device. The experimental result on benzaldehyde, a typical peach flavor, shows the sensor sensitivity 4 ppb, which is superior to the human sensitivity of about 350 ppb. Our developed taste sensor and electronic nose play the role of gustatory and olfactory senses, respectively.

Human immunodeficiency virus (HIV) has no more than nine genes expressing approximately twenty proteins. When T lymphocytes and macrophages in a body are infected with HIV, these proteins work in turn at specific time and location, causing acquired immunodeficiency syndrome (AIDS), a disease yet to be overcome. Since the elucidation of molecular mechanism of HIV proteins should lead to remedy of AIDS, the author has been engaged in the study of HIV protein in the past decade. Described herein are viral protein X (Vpx), uniquely found in HIV-2, and its homologous protein Vpr found both in HIV-1 and -2. We found that Vpx enhances genome nuclear import in T lymphocytes, and is critical for reverse transcription of viral RNA in macrophages. This finding on the function in macrophages corrected long-term misleading belief. Furthermore, functional region mapping of Vpx was performed. In 2011, the protein SAMHD1 was identified as the host restriction factor counteracted by Vpx, by foreign researchers. After that, our independent study demonstrated the presence of SAMHD1-independent functions of Vpx in T cells, in addition to its SAMHD1-dependent functions in macrophages. Another topic of this review is Gag protein. Recently, it has reported by overseas researchers that PI(4,5)P2 (one of phosphoinositide) regulates Pr55(Gag) localization and assembly. In this study, we determined the binding affinity between N-terminal MA domain of Pr55(Gag) and various phosphoinositide derivatives using surface plasmon resonance. The results suggested that both negatively charged inositol phosphates and hydrophobic acyl chain are required for the MA binding.

The measurement of anti-blood group A/B (anti-A/B) IgG antibody levels is important for ABO unmatched-organ recipients because the effective removal of the antibodies improves their prognosis. Living-donor liver transplantation (LDLT) into ABO-unmatched patients tends to have a very poor outcome due to major complications such as intrahepatic bile duct complications and hepatic necrosis. Sustained bile duct complications are associated with high preoperative IgM type anti-A/B Ab titers, while patients with high preoperative IgG type anti-A/B Ab titers frequently develop sustained hepatic necrosis. There are several existing methods by which anti-A/B Ab levels can be measured, including the standard tube (TT) method, an enzyme-linked immunosorbent assay, and a flow cytometry method. Anti-A/B IgG Ab is difficult to identify by the TT method, which is the most popular method and is based on the detection of hemagglutination, because the major isotype that facilitates red cell agglutination is the pentameric IgM molecule. Therefore, we have developed a method based on surface plasmon resonance (SPR) that detects the presence of the antigen-antibody complex without any labeling. This method allows us to rapidly quantitate anti-A/B IgG Ab levels.

A simple, rapid, and accurate assay using surface plasmon resonance (SPR) apparatus with anti-follistatin antibody (SPR immunoassay) has been developed for the quantitation of recombinant follistatin. This assay can be performed with a direct injection of conditioned medium; results were obtained within 10 min. The quantitation component of this assay was precise and accurate with a limit of quantitation of 62.5 ng/ml in Ham's F12 medium containing 2% fetal bovine serum. These results demonstrate that SPR immunoassay is a powerful technique for several researches, especially for screening of gene transfectant and monitoring of protein production.