Kohsuke Gonda

Tohoku University, Sendai, Kagoshima, Japan

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Publications (42)82.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This work performed X-ray imaging of mouse by using aqueous colloid solution of AgI nanoparticles coated with silica (AgI/SiO2) and then surface-modified with poly(ethylene glycol) (PEG) (AgI/SiO2/PEG). A colloid solution of AgI nanoparticles was prepared by mixing silver perchlorate and potassium iodide in water. The AgI nanoparticles were surface-modified with 3-mercaptopropyltrimethoxysilane and then were silica-coated by a sol-gel reaction between tetraethylorthosilicate and H2O catalyzed with NaOH in ethanol. The AgI/SiO2 particle surface was modified with PEG by using methoxy PEG silane . The AgI/SiO2/PEG colloid solution revealed a computed tomography value as high as 1343.6 HU at an iodine concentration of 0.1 M, which was higher than a commercial X-ray contrast agent with the same iodine concentration. Tissues of mouse could be imaged by injecting the concentrated colloid solution into them.
    ISRN Nanomaterials. 07/2013; 2013.
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    ABSTRACT: The mechanisms underlying the cellular entry of the HIV-1-Tat protein transduction domain (TatP) and the molecular information necessary to improve the transduction efficiency of TatP remain unclear due to the technical limitations for direct visualization of TatP's behavior in cells. Using confocal microscopy, total internal reflection fluorescence microscopy, and four-dimensional microscopy, we developed a single-molecule tracking assay for TatP labeled with quantum dots (QDs) to examine the kinetics of TatP initially and immediately before, at the beginning of, and immediately after entry into living cells. We report that even when the number of multivalent-TatP (mTatP)-QDs bound to a cell was low, each single mTatP-QD first locally induced the cell's lateral transport machinery to move the mTatP-QD toward the center of the cell body upon crosslinking of heparan-sulfate proteoglycans (HSPGs). The centripetal and lateral movements were linked to the integrity and flow of actomyosin and microtubules. Individual mTatP underwent lipid raft-mediated temporal confinement, followed by complete immobilization, which ultimately led to endocytotic-internalization. However, bivalent-TatP did not sufficiently promote either cell-surface movement or internalization. Together, these findings provide clues regarding the mechanisms of TatP cell-entry and indicate that increasing the valence of TatP on nanoparticles allows them to behave as cargo-delivery nanomachines.
    Molecular and Cellular Biology 06/2013; · 5.04 Impact Factor
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    ABSTRACT: A preparation method for Gd-ethylenediaminetetraacetic acid disodium salt dihydrate (ETDA) complex-immobilized silica particles (Gd-EDTA/SiO2) is proposed. Preparation of spherical silica particles was performed by a sol-gel method at 35°C using 0.2 M tetraethylorthosilicate, 25 M H2O, and 0.01 M NaOH in ethanol, which produced silica particles with an average size of nm. Immobilization of Gd-EDTA on the silica particles was conducted at 35°C by introducing amino groups on the silica particles with (3-aminopropyl)trimethoxysilane at pH 3 (NH2/SiO2) and then making Gd-EDTA act on the NH2/SiO2 particles at pH 5. The as-prepared Gd-EDTA/SiO2 particle colloid solution was concentrated up to a Gd concentration of 0.347 mM by centrifugation. The sphere structure of Gd-EDTA/SiO2 particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated Gd-EDTA/SiO2 colloid solution revealed good MRI properties. A relaxivity value for T1-weighted imaging was as high as 5.15 mM−1 s−1, that was comparable to that for a commercial Gd complex contrast agent.
    ISRN Nanotechnology. 04/2013; 2013.
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    ABSTRACT: A preparation method for gadolinium compound (GdC) nanoparticles coated with silica () is proposed. GdC nanoparticles were prepared with a homogeneous precipitation method at using M , 0.5 M urea and M ethylenediarinnetetraacetic acid disodium salt dihydrate (ETDA) in water. As a result of preparation at various EDTA concentrations, GdC nanoparticles with a size as small as nm, which were colloidally stable, were prepared at an EDTA concentration of M. Silica-coating of the GdC nanoparticles was performed by a Stber method at using M tetraethylorthosilicate (TEOS), 11 M and M NaOH in ethanol in the presence of M GdC nanoparticles. Performance of preparation at various TEOS concentrations resulted in production of particles with an average size of nm at a TEOS concentration of M. The gadolinium (Gd) concentration of M in the as-prepared particle colloid solution was increased up to a Gd concentration of 0.2 M by concentrating with centrifugation. The core-shell structure of particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated colloid solution showed images of X-ray and magnetic resonance with contrast as high as commercial Gd complex contrast agents.
    Advances in nano research. 01/2013; 1(3).
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    ABSTRACT: This paper describes a method for producing silica particles containing multiple quantum dots (QD/SiO2), a method for surface-modifying the particles with poly(ethylene glycol) (QD/SiO2/PEG), and an in vivo fluorescence imaging technique using colloid solution of the QD/SiO2/PEG particles. The QDs used were ZnS-coated CdSexTe1−x nanoparticles surface-modified with carboxyl groups, and had an average size of 10.3 ± 2.1 nm. The QD/SiO2 particles were fabricated by performing sol–gel reaction of tetraethyl orthosilicate using NaOH as a catalyst in the presence of the QDs. The produced particles formed core–shell structure composed of multiple QDs and silica shell, and had an average size of 50.2 ± 17.9 nm. Surface-modification of the QD/SiO2 particles with PEG, or PEGylation of the particle surface, was performed by using methoxy polyethylene glycol silane. Fluorescence of QD colloid solution was not quenched even through the silica-coating and the PEGylation. Tissues of a mouse could be imaged by injecting the concentrated colloid solution into it and measuring fluorescence intensity emitted from the tissues.
    Journal of Sol-Gel Science and Technology 01/2013; 66(1). · 1.66 Impact Factor
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    ABSTRACT: The detection of estrogen receptors (ERs) by immunohistochemistry (IHC) using 3,3'-diaminobenzidine (DAB) is slightly weak as a prognostic marker, but it is essential to the application of endocrine therapy, such as antiestrogen tamoxifen-based therapy. IHC using DAB is a poor quantitative method because horseradish peroxidase (HRP) activity depends on reaction time, temperature and substrate concentration. However, IHC using fluorescent material provides an effective method to quantitatively use IHC because the signal intensity is proportional to the intensity of the photon excitation energy. However, the high level of autofluorescence has impeded the development of quantitative IHC using fluorescence. We developed organic fluorescent material (tetramethylrhodamine)-assembled nanoparticles for IHC. Tissue autofluorescence is comparable to the fluorescence intensity of quantum dots, which are the most representative fluorescent nanoparticles. The fluorescent intensity of our novel nanoparticles was 10.2-fold greater than quantum dots, and they did not bind non-specifically to breast cancer tissues due to the polyethylene glycol chain that coated their surfaces. Therefore, the fluorescent intensity of our nanoparticles significantly exceeded autofluorescence, which produced a significantly higher signal-to-noise ratio on IHC-imaged cancer tissues than previous methods. Moreover, immunostaining data from our nanoparticle fluorescent IHC and IHC with DAB were compared in the same region of adjacent tissues sections to quantitatively examine the two methods. The results demonstrated that our nanoparticle staining analyzed a wide range of ER expression levels with higher accuracy and quantitative sensitivity than DAB staining. This enhancement in the diagnostic accuracy and sensitivity for ERs using our immunostaining method will improve the prediction of responses to therapies that target ERs and progesterone receptors that are induced by a downstream ER signal.
    Biochemical and Biophysical Research Communications 08/2012; 426(3):409-14. · 2.28 Impact Factor
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    ABSTRACT: Multilayered, core/shell nanoprobes (MQQ-probe) based on magnetic nanoparticles (MNPs) and quantum dots (QDs) have been successfully developed for multimodality tumor imaging. This MQQ-probe contains Fe(3)O(4) MNPs, visible-fluorescent QDs (600 nm emission) and near infrared-fluorescent QDs (780 nm emission) in multiple silica layers. The fabrication of the MQQ-probe involves the synthesis of a primer Fe(3)O(4) MNPs/SiO(2) core by a reverse microemulsion method. The MQQ-probe can be used both as a fluorescent probe and a contrast reagent of magnetic resonance imaging. For breast cancer tumor imaging, anti-HER2 (human epidermal growth factor receptor 2) antibody was conjugated to the surface of the MQQ-probe. The specific binding of the antibody conjugated MQQ-probe to the surface of human breast cancer cells (KPL-4) was confirmed by fluorescence microscopy and fluorescence-activated cell sorting analysis in vitro. Due to the high tissue permeability of near-infrared (NIR) light, NIR fluorescence imaging of the tumor mice (KPL-4 cells transplanted) was conducted by using the anti-HER2 antibody conjugated MQQ-probe. In vivo multimodality images of breast tumors were successfully taken by NIR fluorescence and T(2)-weighted magnetic resonance. Antibody conjugated MQQ-probes have great potential to use for multimodality imaging of cancer tumors in vitro and in vivo.
    Biomaterials 08/2012; 33(33):8486-94. · 8.31 Impact Factor
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    ABSTRACT: Methods for high concentration silica-coated silver iodide (AgI/SiO2) particles, which could be practically used as X-ray contrast agent, were examined. The first was a single-step method, which was to prepare AgI nanoparticles at an AgI concentration of 5 x 10(-3) M and coat the AgI nanoparticles with silica shell by a Stöber method. The second was a multiple-step method, which was to repeat a step for preparing a AgI/SiO2 particle colloid solution with 10(-3) M AgI 5 times for adjusting a final AgI concentration to 5 x 10(-3) M. In the two methods, dominant particle aggregation took place, though core-shell particles were also produced. The third was a salting-out method, which was to salt out AgI/SiO2 particles in their colloid solution prepared at an AgI concentration of 10(-3) M, remove supernatant by decantation, and redisperse the particles in a fresh solvent. Consequently, AgI/SiO2 particles with an AgI concentration as high as 0.05 M were successfully prepared with the salting-out method, and their core-shell structure was not damaged during the salting-out.
    Journal of Nanoscience and Nanotechnology 08/2012; 12(8):6741-5. · 1.15 Impact Factor
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    ABSTRACT: Mucociliary clearance on the surface of the tracheal lumen is an important component of lung defense against dust mites and viruses. However, the axonemal structure that achieves effective ciliary motion and the mechanisms by which discretely distributed ciliary cells generate directional flow are unknown. In this study, we examined individual ciliary motion with 7–9-nm spatial precision by labeling the ciliary tip with quantum dots, and detected an asymmetric beating pattern. Cryo-electron tomography revealed that the densities of two inner dynein arms were missing from at least two doublet microtubules in the axonemal structure. Although the flow directions generated by individual ciliated cells were unsteady and diverse, the time- and space-averaged velocity field was found to be directional. These results indicate that the asymmetric ciliary motion is driven by the asymmetric axonemal structure, and it generates overall directional flow from the lungs to the oropharynx on sparsely distributed ciliated cells.
    ASME 2012 Summer Bioengineering Conference; 06/2012
  • Journal of Materials Science 02/2012; 47(4):1852-1859. · 2.31 Impact Factor
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    ABSTRACT: Mucociliary clearance on the surface of the tracheal lumen is an important component of lung defense against dust mites and viruses. However, the axonemal structure that achieves effective ciliary motion, and the mechanisms by which discretely distributed ciliary cells generate directional flow are unknown. In this study, we examined individual ciliary motion with 7- to 9-nm spatial precision by labeling the ciliary tip with quantum dots and detected an asymmetric beating pattern. Cryo-electron tomography revealed that the densities of two inner dynein arms were missing from at least 2 doublet microtubules in the axonemal structure. Although the flow directions generated by individual ciliated cells were unsteady and diverse, the time- and space-averaged velocity field was found to be directional. These results indicate that the asymmetric ciliary motion is driven by the asymmetric axonemal structure, and it generates overall directional flow from the lungs to the oropharynx on sparsely distributed ciliated cells. FROM THE CLINICAL EDITOR: The authors of this study utilized quantum dots in determining the kinetics of ciliary motion in mouse respiratory cilia with 7- to 9-nm spatial precision.
    Nanomedicine: nanotechnology, biology, and medicine 01/2012; 8(7):1081-7. · 6.93 Impact Factor
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
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    ABSTRACT: Nanomaterials have great potential in the field of medicine and have been studied extensively. In a previous study, we addressed the potential of silver iodide (AgI) as X-ray contrast media, because it possessed high imaging ability in the measurement by X-ray computed tomography (X-CT) in vitro, and its surface can be modified with many functional groups. We developed the method of silica coating to make AgI nanoparticles more stable and uniform in size. However, the safety and metabolism of nanoparticles in vivo remains to be determined. The objective of the present study was to evaluate the in vivo biodistribution of silica-coated AgI nanoparticles (SAgINPs). X-CT, transmission electron microscopy (TEM), and inductively coupled plasma atomic emission spectrometry (ICP-AES) were performed prior to and at intervals following the intravenous administration of SAgINPs to rats and rabbits. ICP-AES is a spectral technique that can determine the presence and concentrations of metal samples. The X-CT study showed long-period enhancement in the liver and spleen, but not in the bladder of rats. The TEM study demonstrated that SAgINPs were found in hepatocytes. Using ICP-AES, Ag was detected in the bile juice of rabbits, but not found in the urine of these animals, suggesting that SAgINPs are excreted via the liver. This study shows the quantitative biodistribution of silica-coated nanoparticles for the first time, indicating that our silica coating technique is useful for development of nanoparticles with hepatic excretion. In conclusion, the SAgINPs may provide X-ray contrast media with high imaging ability and biocompatibility.
    The Tohoku Journal of Experimental Medicine 01/2012; 228(4):317-23. · 1.37 Impact Factor
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
  • Nano-Biomedical Engineering 2012 - The Tohoku University Global Centre of Excellence Programme; 01/2012
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    ABSTRACT: A preparation method for gadolinium compound (Gd) nanoparticles coated with silica (Gd/SiO2) is proposed. Gd nanoparticles were prepared with a homogeneous precipitation method at 80°C using 1.0×10−3 M Gd(NO3)3 and 0.5M urea in the presence of 1.0g/L stabilizer. Among stabilizers examined. Sodium n-dodecyl sulfate (SDS) was suitable as the stabilizer for preparing small Gd nanoparticles, and consequently Gd nanoparticles with a size of 46.2±12.4nm were prepared using the SDS. Silica-coating of the Gd nanoparticles was performed by a Stöber method at room temperature using 0.013M TEOS and 2.0×10−3M NaOH in water/1-propanol solution in the presence of 1.0×10−3M Gd nanoparticles, which resulted in production of Gd/SiO2 particles with an average size of 64.2±14.4nm. The Gd/SiO2 particles were surface-modified with 3-aminopropyltrimethoxysilane and succinic anhydride. It was confirmed by measurement of electrophretic light scattering that amino group or carboxyl group was introduced onto the Gd/SiO2 particles. The gadolinium concentration of 1.0×10−3M in the as-prepared colloid solution was increased up to a gadolinium concentration of 0.4M by centrifugation. The core–shell structure of Gd/SiO2 particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated Gd/SiO2 colloid solution showed an X-ray image with contrast as high as a commercial Gd complex contrast agent. Internal organs in a mouse could be imaged injecting the concentrated colloid solution into it. KeywordsCore–shell–Particle–Gadolinium–Silica–Homogeneous precipitation method–X-ray imaging
    Journal of Sol-Gel Science and Technology 09/2011; 59(3):650-657. · 1.66 Impact Factor
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    ABSTRACT: Vascular endothelial growth factor (VEGF) plays a critical role in angiogenesis and has been applied to medical therapy. However, because vascular imaging at the molecular level is impossible, the detailed in vivo dynamics of VEGF and its receptor (VEGFR) remain unknown. In this study, to understand the molecular distribution of VEGF and the VEGFR, we prepared ischemic mice with a new surgical method and induced angiogenesis in the gastrocnemius muscle. Then, we made a VEGF-conjugated fluorescence nanoparticle and performed staining of VEGFR-expressing cells with the fluorescent probe, demonstrating the high affinity of the probe for VEGFR. To observe the physiologic molecular distribution of VEGFR, we performed in vivo single-particle imaging of gastrocnemius in the ischemic leg with the fluorescent probe. The results suggested that only a 3-fold difference of VEGFR distribution is involved in the formation of branched vasculature in angiogenesis, although previous ex vivo data showed a 13-fold difference in its distribution, indicating that a method inducing a several-fold local increase of VEGFR concentration may be effective in generating site-specific angiogenesis in ischemic disease. This new in vivo imaging of ischemic mice could make useful contributions to understanding the mechanisms of angiogenesis and to developing a VEGFR-related drug.
    Blood 08/2011; 118(13):e93-e100. · 9.78 Impact Factor

Publication Stats

184 Citations
82.03 Total Impact Points

Institutions

  • 2007–2013
    • Tohoku University
      • • Department of Surgical Oncology
      • • Graduate School of Medicine
      Sendai, Kagoshima, Japan
  • 2011–2012
    • Ibaraki University
      • College of Engineering
      Mito-shi, Ibaraki-ken, Japan
  • 2004
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan