Siliconbio Inc.

Higashi Hiroshima, Japan

Siliconbio Inc.

Higashi Hiroshima, Japan
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Nishimura T.,Hiroshima University | Nishimura T.,Siliconbio Inc. | Alexandrov M.,Hiroshima University | Ishida T.,Hiroshima University | And 5 more authors.
Annals of Occupational Hygiene | Year: 2016

Considering the increasing use of various asbestos substitutes, asbestos risk management in many industries may require accurate techniques for detecting and distinguishing asbestos from non-asbestos fibers. Using fluorescently labeled asbestos-binding proteins, we previously developed a novel method for detection and counting of asbestos fibers under fluorescence microscopy (FM). This method can provide speedy, on-site detection and identification of the asbestos fibers and has higher sensitivity than phase contrast microscopy (PCM). However, current asbestos exposure limits are derived from risk assessments based on epidemiological studies that were conducted using PCM fiber counts. Therefore, the sensitivity of asbestos testing should be maintained at PCM level to properly assess compliance with these limit values. Here, we developed and tested a novel application of FM as a differential counting method that complements PCM analysis and is fully compatible with the PCM-based epidemiological data. In the combined PCM-FM method, the fluorescent asbestos-binding probe is applied prior to filter clearing. The method makes it possible to easily switch between two microscopic techniques while analyzing the same fields of view: PCM is used for counting fibers, and FM for differentiating asbestos from non-asbestos fibers. Using airborne dust samples from demolition sites in Japan, we compared PCM-FM with scanning electron microscopy (SEM)-based differential counting method. Statistical analysis indicated a slight conservative bias of PCM-FM method, combined with relatively high variability across the full range of fiber concentrations in our sample set. Using correlative microscopy, we also evaluated the specificity of FM staining, which is a potential cause of variability between the two methods. The energy-dispersive X-ray analysis indicated that ∼95% of fluorescently stained fibers in the demolition site samples were correctly identified as asbestos. While further research is needed to fully clarify the causes of variability between FM- and SEM-based differential counting, PCM-FM could be used for rapid and selective detection of asbestos fibers in field samples. © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Ishida T.,Hiroshima University | Alexandrov M.,Hiroshima University | Nishimura T.,Siliconbio Inc. | Minakawa K.,Siliconbio Inc. | And 5 more authors.
Environmental Science and Technology | Year: 2010

Fluorescence microscopy (FM) is one of the most important analytical tools in modern life sciences, sufficiently sensitive to allow observation of single molecules. Here we describe the first application of the FM technique for the detection of inorganic environmental pollutants - airborne asbestos fibers that can cause asbestosis, mesothelioma, and lung cancer. In order to assess FM capabilities for detecting and counting asbestos fibers, we screened E. coli lysate for proteins that bind to amphibole asbestos. In combination with the previously discovered E. coli protein DksA (Kuroda et al., Biotechnol. Bioeng. 2008, 99, 285-289) that can specifically bind to chrysotile, the newly identified GatZ protein was used for selective and highly sensitive detection of two different asbestos types. Our novel FM-based method overcomes a number of limitations of the commonly used phase-contrast microscopy (PCM) method, offering a convenient alternative to PCM for airborne asbestos monitoring. © 2010 American Chemical Society.

Ikeda T.,Hiroshima University | Ueda T.,Precision System Science Co. | Tajima H.,Precision System Science Co. | Sekiguchi K.,Siliconbio Inc. | And 2 more authors.
Analytical Methods | Year: 2014

An automated enzyme-linked immunosorbent assay (ELISA) system was developed using beads in a single tip (BIST) technology. Sandwich ELISA was performed on glass beads functionalized with a capture antibody via the fusion of antibody-binding streptococcal protein G and a silica/glass-binding protein Si-tag. Our system enables rapid, sensitive detection of antigens. This journal is © the Partner Organisations 2014.

Ishida T.,Hiroshima University | Alexandrov M.,Hiroshima University | Nishimura T.,Hiroshima University | Minakawa K.,Hiroshima University | And 4 more authors.
Journal of Fluorescence | Year: 2012

Fluorescence microscopy (FM) has recently been applied to the detection of airborne asbestos fibers that can cause asbestosis, mesothelioma and lung cancer. In our previous studies, we discovered that the E. coli protein DksA specifically binds to the most commonly used type of asbestos, chrysotile. We also demonstrated that fluorescentlabeled DksA enabled far more specific and sensitive detection of airborne asbestos fibers than conventional phase contrast microscopy (PCM). However, the actual diameter of the thinnest asbestos fibers visualized under the FM platform was unclear, as their dimensions were below the resolution of optical microscopy. Here, we used correlative microscopy (scanning electron microscopy [SEM] in combination with FM) to measure the actual diameters of asbestos fibers visualized under the FM platform with fluorescent-labeled DksA as a probe. Our analysis revealed that FM offers sufficient sensitivity to detect chrysotile fibrils as thin as 30-35 nm. We therefore conclude that as an analytical method, FM has the potential to detect all countable asbestos fibers in air samples, thus approaching the sensitivity of SEM. By visualizing thin asbestos fibers at approximately tenfold lower magnifications, FM enables markedly more rapid counting of fibers than SEM. Thus, fluorescence microscopy represents an advanced analytical tool for asbestos detection and monitoring. © 2011 Springer Science+Business Media, LLC.

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