Kohsuke Gonda

Tohoku University, Sendai-shi, Miyagi, Japan

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Publications (68)130 Total impact

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    ABSTRACT: Mn-Zn ferrite, Mn1− x Zn x Fe2O4 nanoparticles encapsulated in amorphous SiO2 were prepared using our original wet chemical method. X-ray diffraction patterns confirmed that the diameters of these particles were within 7-30 nm. Magnetization measurements for various sample compositions revealed that the saturation magnetization (M s) of 7 nm particles was maximum for the x = 0.2 sample. AC magnetic susceptibility measurements were performed for Mn0.8 Zn 0.2Fe2O4 (x = 0.2) samples with 13-30 nm particles. The peak of the imaginary part of the magnetic susceptibility χ″ shifted to higher temperatures as the particle size increased. An AC field was found to cause the increase in temperature, with the 18 nm particles exhibiting the highest temperature increase, as expected. In addition, in vitro experiments were carried out to study the hyperthermia effects of Mn1− x Zn x Fe2O4 (x = 0.2, 18 nm) particles on human cancer cells.
    Journal of Applied Physics 05/2015; 117(17):17D157. DOI:10.1063/1.4919327 · 2.19 Impact Factor
  • 05/2015; 1(2):83-88. DOI:10.1179/2055033215Y.0000000003
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    ABSTRACT: This paper proposes a method for fabricating gadolinium diethylenetriamine pentaacetic acid-immobilized silica particles (SiO2/Gd-DTPA). Preparation of a colloid solution of spherical silica particles with an average size of 101.7±11.7 nm 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. Amino groups were introduced on the silica particles with 6 × 10−3 M (3- aminopropyl)triethoxysilane (APES) at 35°C (SiO2-NH2), which resulted in their average particle of 80.5±9.7 nm. Gd-DTPA was immobilized on the SiO2-NH2 particle surface with 5 × 10−4 M Gd-DTPA in 50/50 (v/v) water/dimethylformamide solution at 35°C , which provided their average particle of 101.6±12.3 nm. The APES-introduction and the Gd-DTPA-immobilization did not change the spherical structure, and shifted an iso-electric point of particles to higher pH for the APES-introduction and then to lower pH for the Gd-DTPA-immobilization, which indicated that APES and Gd-DTPA were successfully attached on the particle surface with no chemical damage. A relaxivity value for T1-weighted imaging of the SiO2/Gd-DTPA particle colloid solution was 2.7 mM−1 s−1, that was 64% of that for Magnevist. [DOI: 10.1380/ejssnt.2015.42]
    e-Journal of Surface Science and Nanotechnology 01/2015; 13:42-46. DOI:10.1380/ejssnt.2015.42
  • Journal of chemical engineering of Japan 01/2015; 48(2):112-117. DOI:10.1252/jcej.14we218 · 0.61 Impact Factor
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    ABSTRACT: The present work proposes preparation methods for quantum dot/silica (QD/SiO2) core-shell particles that immobilize Au nanoparticles (QD/SiO2/Au). A colloid solution of QD/SiO2 core-shell particles with an average size of 47.0 ± 6.1 nm was prepared by a sol-gel reaction of tetraethyl orthosilicate in the presence of the QDs with an average size of 10.3 ± 2.1 nm. A colloid solution of Au nanoparticles with an average size of 17.9 ± 1.3 nm was prepared by reducing Au3+ ions with sodium citrate in water at 80 °C. Introduction of amino groups to QD/SiO2 particle surfaces was performed using (3-aminopropyl)-triethoxysilane (QD/SiO2-NH2). The QD/SiO2/Au particles were fabricated by mixing the Au particle colloid solution and the QD/SiO2-NH2 particle colloid solution. Values of radiant efficiency and computed tomography for the QD/SiO2/Au particle colloid solution were 2.23 × 107 (p/s/cm2/sr)/(μW/cm2) at a QD concentration of 8 × 10−7 M and 1180 ± 314 Hounsfield units and an Au concentration of 5.4 × 10−2 M. The QD/SiO2/Au particle colloid solution was injected into a mouse chest wall. Fluorescence emitted from the colloid solution could be detected on the skin covering the chest wall. The colloid solution could also be X-ray-imaged in the chest wall. Consequently, the QD/SiO2/Au particle colloid solution was found to have dual functions, i.e., fluorescence emission and X-ray absorption in vivo, which makes the colloid solution suitable to function as a contrast agent for dual imaging processes.
    01/2015; DOI:10.1007/s13204-015-0440-8
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    ABSTRACT: Neoadjuvant chemotherapy has been increasingly utilized in the treatment of breast cancer patients. However, there are no established surrogate markers predicting the response to subsequent adjuvant therapy and clinical outcome of patients. In particular, whether primary or lymph nodes metastasis should be evaluated for these analyses has remained unknown. Therefore, in this study, we first evaluated the differences in biomarkers between primary and metastatic cancer tissues in the patients undergoing neoadjuvant chemotherapy. We then correlated the findings with the clinical outcomes of these patients. We examined 49 patients receiving neoadjuvant chemotherapy and subsequent surgery with lymph node metastasis. Estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2) and Ki-67 were all immunohistochemically evaluated in core needle biopsy samples from primary and metastatic tumors following chemotherapy. No statistically significant differences in these markers were detected between the primary tumor and metastatic lymph nodes following therapy, but the Ki-67 labeling index was significantly higher in metastatic lymph nodes than in primary tumor (p = 0.017). The patients associated with luminal A type carcinoma in their lymph nodes following chemotherapy demonstrated significantly better clinical outcomes (disease-free survival: p = 0.0045, overall survival: p = 0.0006) than those who were not. These data indicate that subtype classification following chemotherapy, in the metastatic lymph nodes rather than primary tumor could predict long-term outcomes of patients undergoing neoadjuvant chemotherapy.
    The International journal of biological markers 12/2014; DOI:10.5301/jbm.5000128 · 1.36 Impact Factor
  • Journal of Nanoparticle Research 08/2014; 16(8). DOI:10.1007/s11051-014-2551-7 · 2.28 Impact Factor
  • Cancer Research 03/2014; 73(24 Supplement):P3-05-16-P3-05-16. DOI:10.1158/0008-5472.SABCS13-P3-05-16 · 9.28 Impact Factor
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    ABSTRACT: This work describes X-ray imaging of mouse using colloid solution of silica coated Au (Au/SiO2) nanoparticles surface modified with poly(ethylene glycol) (PEG) (Au/SiO2/PEG). A colloid solution of Au nanoparticles was prepared by reducing Au ions (III) with sodium citrate. Au/SiO2 nanoparticles were fabricated by a sol–gel method using tetraethylorthosilicate, water and sodium hydroxide in ethanol in the presence of Au nanoparticles surface modified with (3-aminopropyl)trimethoxysilane. A computed tomography value of the Au/SiO2 colloid solution with an Au concentration of 0·083M was as high as 1421·2 Hounsfield units, which was higher than that of a commercial X-ray contrast agent with the same iodine concentration. Surface modification of the Au/SiO2 particles with PEG, or PEGylation of the particle surface, was performed using (3-aminopropyl)trimethoxysilane and PEG for the Au/SiO2 particles. Tissues of mouse could be imaged by injecting the colloid solutions of Au/SiO2 particles or Au/SiO2/PEG particles into it. The PEGylation provided an increase in residence time of particles in the mouse.
    Material Research Innovations 11/2013; 17(7):507-514. DOI:10.1179/1433075X13Y.0000000100 · 0.47 Impact Factor
  • 10/2013; 2(5):369-373. DOI:10.1166/mat.2013.1104
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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.
    09/2013; 1(3). DOI:10.12989/anr.2013.1.3.159
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    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.
    07/2013; 2013. DOI:10.1155/2013/670402
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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; DOI:10.1128/MCB.01717-12 · 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.
    04/2013; 2013. DOI:10.1155/2013/908614
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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 04/2013; 66(1). DOI:10.1007/s10971-013-2962-4 · 1.55 Impact Factor
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    ABSTRACT: A preparation method for hollow particles composed of silica shell containing gadolinium compound (GdC) is proposed. GdC nanoparticles with an average size of 40.5 ± 6.2 nm were prepared with a homogeneous precipitation method at 80°C using 1.0 × 10−3 M Gd(NO3)3 and 0.5 M urea in the presence of 2.0 × 10−4 M ethylenediaminetetraacetic acid disodium salt dihydrate. Silica-coated GdC (GdC/SiO2) nanoparticles with an average size of 100.9 ± 9.9 nm were fabricated with a sol-gel method at 35°C using 5.0 × 10−3 M tetraethylorthosilicate, 11 M H2O, and 1.5 × 10−3 M NaOH in ethanol in the presence of 1.0 × 10−3 M GdC nanoparticles. The GdC/SiO2 particles were aged at 80°C in water after replacement of solvent of the as-prepared GdC/SiO2 particle colloid solution with water, which provided diffusion of GdC into the silica shell and then formation of a hollow structure. The hollow particle colloid solution revealed good MRI properties. A relaxivity value for longitudinal relaxation time-weighted imaging was as high as 3.38 mM−1 · s−1 that attained 80% of that for a commercial Gd complex contrast agent.
    01/2013; 3(1). DOI:10.1186/2193-8865-3-11
  • 01/2013; 3(1):62. DOI:10.1186/2193-8865-3-62
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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 12/2012; 228(4):317-23. DOI:10.1620/tjem.228.317 · 1.28 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. DOI:10.1016/j.bbrc.2012.08.105 · 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. DOI:10.1016/j.biomaterials.2012.07.051 · 8.31 Impact Factor

Publication Stats

439 Citations
130.00 Total Impact Points


  • 2007–2015
    • Tohoku University
      • • Graduate School of Medicine
      • • Department of Surgical Oncology
      • • Department of Emerging Infectious Diseases
      • • Department of Advanced Surgical Science and Technology
      Sendai-shi, Miyagi, Japan
  • 1999–2004
    • University of Tsukuba
      • Institute of Biological Sciences
      Tsukuba, Ibaraki, Japan