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Ueno H, Akagi Y, Yamamura S. Selective cell retrieval method using light-responsive gas-generating polymer-based microarrays. LAB ON A CHIP 2022; 22:1498-1507. [PMID: 35311840 DOI: 10.1039/d1lc01165k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Selective cell retrieval from base material is necessary for developing and improving cell analyzing technologies as well as regenerative medicine. Many conventional technologies, such as micromanipulators, are developed for selective cell retrieval. However, selective cell retrieval at the single-cell level remains challenging because it is quite difficult to retrieve adhered single cells from base material with ease, rapidity, and no damage. Here, we propose a novel selective cell retrieval method using microarrays made of a light-responsive gas-generating polymer (LGP microarray). The convex LGP microarray was fabricated by a molding process using polystyrene microarray chips. LGP microarrays generate N2 gas when exposed to a specific light used for fluorescence microscopy. A human cervical cancer cell (HeLa) suspension was spread on the LGP microarray coated by fibronectin. After these HeLa cells were adhered to the surface of the LGP microarray structure, light at a wavelength of 365 nm was used to irradiate the LGP microarray. All the target HeLa cells were selectively released from the light-irradiated surface area of the LGP microarray by the generated N2 gas. The LGP microarray system was also applied to single-cell retrieval, and we easily and rapidly retrieved 100% of the single HeLa cells from the microarrays. In addition, approximately 90% of single HeLa cells retrieved from the LGP microarray proliferated on a chamber of a 96-well plate. Therefore, the LGP microarray system enables easy and selective retrieval of adhered cell groups or single cells with only harmless light irradiation.
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Affiliation(s)
- Hidetaka Ueno
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan.
| | - Yoshinori Akagi
- R&D Center Corporate Advanced Technology Institute Life Science Development Center, Sekisui Chemical Co., Ltd., 2-1 Hyakuyama, Shimamoto-cho, Mishima-gun, Osaka 618-0021, Japan
| | - Shohei Yamamura
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan.
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Novel Quick Cell Patterning Using Light-Responsive Gas-Generating Polymer and Fluorescence Microscope. MICROMACHINES 2022; 13:mi13020320. [PMID: 35208444 PMCID: PMC8875422 DOI: 10.3390/mi13020320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/07/2022] [Accepted: 02/12/2022] [Indexed: 02/04/2023]
Abstract
Conventional cell patterning methods are mainly based on hydrophilic/hydrophobic differences or chemical coating for cell adhesion/non-adhesion with wavering strength as it varies with the substrate surface conditions, including the cell type and the extracellular matrix components (ECMs) coating; thus, the versatility and stability of cell patterning methods must be improved. In this study, we propose a new cell patterning method using a light-responsive gas-generating polymer (LGP) and a conventional fluorescence microscope. Herein, cells and cellular tissues are easily released from the substrate surface by the nitrogen gas bubbles generated from LGP by the excitation light for fluorescence observation without harming the cells. The LGP-implanted chip was fabricated by packing LGP into a polystyrene (PS) microarray chip with a concave pattern. HeLa cells were spread on the LGP-implanted chips coated with three different ECMs (fibronectin, collagen, and poly-D-lysine), and all HeLa cells on the three LGP patterns were released. The pattern error between the LGP pattern and the remaining HeLa cells was 8.81 ± 4.24 μm, less than single-cell size. In addition, the LGP-implanted chip method can be applied to millimeter-scale patterns, with less than 30 s required for cell patterning. Therefore, the proposed method is a simple and rapid cell patterning method with high cell patterning accuracy of less than the cell size error, high scalability, versatility, and stability unaffected by the cell type or the ECM coating.
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Yamaguchi S, Takasaki Y, Yamahira S, Nagamune T. Photo-Cleavable Peptide-Poly(Ethylene Glycol) Conjugate Surfaces for Light-Guided Control of Cell Adhesion. MICROMACHINES 2020; 11:E762. [PMID: 32784375 PMCID: PMC7465029 DOI: 10.3390/mi11080762] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/31/2020] [Accepted: 08/06/2020] [Indexed: 12/17/2022]
Abstract
Photo-responsive cell attachment surfaces can simplify patterning and recovery of cells in microdevices for medicinal and pharmaceutical research. We developed a photo-responsive surface for controlling the attachment and release of adherent cells on a substrate under light-guidance. The surface comprises a poly(ethylene glycol) (PEG)-based photocleavable material that can conjugate with cell-adhesive peptides. Surface-bound peptides were released by photocleavage in the light-exposed region, where the cell attachment was subsequently suppressed by the exposed PEG. Simultaneously, cells selectively adhered to the peptide surface at the unexposed microscale region. After culture, the adhered and spread cells were released by exposure to a light with nontoxic dose level. Thus, the present surface can easily create both cell-adhesive and non-cell-adhesive regions on the substrate by single irradiation of the light pattern, and the adhered cells were selectively released from the light-exposed region on the cell micropattern without damage. This study shows that the photo-responsive surface can serve as a facile platform for the remote-control of patterning and recovery of adherent cells in microdevices.
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Affiliation(s)
- Satoshi Yamaguchi
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Hon-cho, Kawaguchi, Saitama 351-0198, Japan
| | - Yumi Takasaki
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shinya Yamahira
- Center for Medical Sciences, St. Luke’s International University, 3-6-2 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Teruyuki Nagamune
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Analysis of Single Nucleotide-Mutated Single-Cancer Cells Using the Combined Technologies of Single-Cell Microarray Chips and Peptide Nucleic Acid-DNA Probes. MICROMACHINES 2020; 11:mi11070628. [PMID: 32605095 PMCID: PMC7407912 DOI: 10.3390/mi11070628] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 12/12/2022]
Abstract
Research into cancer cells that harbor gene mutations relating to anticancer drug-resistance at the single-cell level has focused on the diagnosis of, or treatment for, cancer. Several methods have been reported for detecting gene-mutated cells within a large number of non-mutated cells; however, target single nucleotide-mutated cells within a large number of cell samples, such as cancer tissue, are still difficult to analyze. In this study, a new system is developed to detect and isolate single-cancer cells expressing the T790M-mutated epidermal growth factor receptor (EGFR) mRNA from multiple non-mutated cancer cells by combining single-cell microarray chips and peptide nucleic acid (PNA)-DNA probes. The single-cell microarray chip is made of polystyrene with 62,410 microchambers (31-40 µm diameter). The T790M-mutated lung cancer cell line, NCI-H1975, and non-mutated lung cancer cell line, A549, were successfully separated into single cells in each microchambers on the chip. Only NCI-H1975 cell was stained on the chip with a fluorescein isothiocyanate (FITC)-conjugated PNA probe for specifically detecting T790M mutation. Of the NCI-H1975 cells that spiked into A549 cells, 0–20% were quantitatively analyzed within 1 h, depending on the spike concentration. Therefore, our system could be useful in analyzing cancer tissue that contains a few anticancer drug-resistant cells.
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Ueno H, Maruo K, Inoue M, Kotera H, Suzuki T. Cell Culture on Low-Fluorescence and High-Resolution Photoresist. MICROMACHINES 2020; 11:mi11060571. [PMID: 32512915 PMCID: PMC7345055 DOI: 10.3390/mi11060571] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 01/09/2023]
Abstract
2D and 3D topographic cues made of photoresist, a polymer, are used for cell culture and cell analysis. Photoresists used for cell analysis provide the surface conditions necessary for proper cell growth, along with patterning properties of a wide range and high precision, and low auto-fluorescence that does not affect fluorescence imaging. In this study, we developed a thick negative photoresist SJI-001 possessing the aforementioned properties. We evaluated the surface conditions of SJI-001 affecting cell culture. First, we studied the wettability of SJI-001, which was changed by plasma treatment, conducted as a pretreatment on a plastic substrate before cell seeding. SJI-001 was more chemically stable than SU-8 used for fabricating the micro-electromechanical systems (MEMS). Furthermore, the doubling time and adhesion rate of adherent HeLa cells cultured on untreated SJI-001 were 25.2 h and 74%, respectively, thus indicating its suitability for cell culture over SU-8. In addition, we fabricated a cell culture plate with a 3D lattice structure, three micrometers in size, using SJI-001. HeLa cells seeded on this plate remained attached over five days. Therefore, SJI-001 exhibits surface conditions suitable for cell culture and has several bioapplications including microstructures and cell chips for cell culture and cell analysis.
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Affiliation(s)
- Hidetaka Ueno
- Division of Mechanical Science and Technology, Gunma University, Kiryu 376-8515, Japan;
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology, 2217-14 Hayashi-cho, Takamatsu 761-0395, Japan
| | - Katsuya Maruo
- Innovation Park, Daicel Corporation, Himeji 671-1283, Japan;
| | - Masatoshi Inoue
- Division of Intelligent Mechanical Systems Engineering, Kagawa University, Takamatsu 761-0396, Japan;
| | | | - Takaaki Suzuki
- Division of Mechanical Science and Technology, Gunma University, Kiryu 376-8515, Japan;
- Correspondence: ; Tel.: +81-277-30-1579
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Ido Y, Hashimoto M, Yatsushiro S, Tanaka M, Yokota K, Kajimoto K, Kataoka M. Loop-Mediated Isothermal Amplification In Microchambers On A Cell Microarray Chip For Identification of Plasmodium Species. J Parasitol 2019. [PMID: 30807712 DOI: 10.1645/18-107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Malaria is caused by Plasmodium spp., a parasitic protist that infects erythrocytes. A method that can detect the parasite with high sensitivity and that can identify the parasite species is urgently required for the control of malaria. The cell microarray chip was made using polystyrene with 200 cone-shaped frustum microchambers (800-μm top diameter, 636-μm bottom diameter, and 225 μm deep). Approximately 3,000 erythrocytes could be accommodated in each microchamber with monolayer formation, there being 60,000 erythrocytes in total microchambers on a cell microarray. Plasmodium could be quantitatively detected with high sensitivity with the use of cell microarray chips. Plasmodium parasitizing in erythrocytes was labeled with a cell-permeant fluorescent nucleic acid stain (SYTO 21), which could be detected in erythrocytes in the microchambers. Next, we used loop-mediated isothermal amplification (LAMP) in the microchambers (on-chip LAMP) to identify the parasite species detected in the microchambers. LAMP was performed in the microchambers (in a reaction volume of 0.09 μl) using Plasmodium falciparum-infected erythrocytes as the template and specific primers targeting 18S rRNA. To avoid evaporation of the reaction buffer during heat treatment, mineral oil was overlaid on each microchamber and the cell microarray chips were heated at 63 C for 1 hr. The results of on-chip LAMP were assessed using a portable ultraviolet transilluminator. We showed that this method has the potential for detection of parasites in 600,000 erythrocytes and for identification of the parasite species on a cell microarray chip. In conclusion, the parasites can be detected quantitatively with high sensitivity, and the species can be identified with the use of cell microarray chips.
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Affiliation(s)
- Yusuke Ido
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan.,2 Present address: Institute for Genome Research, Tokushima University, Kuramotocho-3, Tokushima 770-8503, Japan
| | - Muneaki Hashimoto
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Shouki Yatsushiro
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Masato Tanaka
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Kazumichi Yokota
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Kazuaki Kajimoto
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Masatoshi Kataoka
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
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Hashimoto M, Sakamoto H, Ido Y, Tanaka M, Yatsushiro S, Kajimoto K, Kataoka M. In situ loop-mediated isothermal amplification (LAMP) for identification of Plasmodium species in wide-range thin blood smears. Malar J 2018; 17:235. [PMID: 29914490 PMCID: PMC6006833 DOI: 10.1186/s12936-018-2381-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 06/09/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Five species of Plasmodium are known to infect humans. For proper treatment of malaria, accurate identification of the parasite species is crucial. The current gold standard for malaria diagnosis is microscopic examination of Giemsa-stained blood smears. Since the parasite species are identified by microscopists who manually search for the parasite-infected red blood cells (RBCs), misdiagnosis due to human error tends to occur in case of low parasitaemia or mixed infection. Then, molecular methods, such as polymerase chain reaction or loop-mediated isothermal amplification (LAMP), are required for conclusive identification of the parasite species. However, since molecular methods are highly sensitive, false-positive results tend to occur due to contamination (carry over) or the target gene products may be detected even after clearance of the parasites from the patient's blood. Therefore, accurate detection of parasites themselves by microscopic examination is essential for the definitive diagnosis. Thus, the method of in situ LAMP for the parasites was developed. RESULTS Red blood cell suspensions, including cultured Plasmodium falciparum, strain 3D7, infected-RBCs, were dispersed on cyclic olefin copolymer (COC) plate surfaces rendered hydrophilic by reactive ion-etching treatment using a SAMCO RIE system (hydrophilic-treated), followed by standing for 10 min to allow the RBCs to settle down on the plate surface. By rinsing the plate with RPMI 1640 medium, monolayers of RBCs formed on almost the entire plate surface. The plate was then dried with a hair drier. The RBCs were fixed with formalin, followed by permeabilization with Triton X-100. Then, amplification of the P. falciparum 18S rRNA gene by the LAMP reaction with digoxigenin (DIG)-labelled dUTP and a specific primer set was performed. Infected RBCs as fluorescence-positive cells with anti-DIG antibodies conjugated with fluorescein using fluorescent microscopy could be detected. CONCLUSIONS The present work shows that the potential of in situ LAMP for the identification of Plasmodium species at the single cell level on hydrophilic-treated COC palates, allowing highly sensitive and accurate malaria diagnosis. The findings will improve the efficacy of the gold standard method for malaria diagnosis.
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Affiliation(s)
- Muneaki Hashimoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan.
| | - Hirokazu Sakamoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan.,Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yusuke Ido
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Masato Tanaka
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Shouki Yatsushiro
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Kazuaki Kajimoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Masatoshi Kataoka
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
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Hashimoto M, Numata M, Yatsushiro S, Ido Y, Tanaka M, Kajimoto K, Kataoka M. Pseudo-Infected Red Blood Cell Beads as Positive Control for Cell Microarray Chip-Based Detection of Plasmodium-Infected RBCs. J Parasitol 2018; 104:283-288. [PMID: 29378156 DOI: 10.1645/17-144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The cell microarray chip is a polystyrene plate with 20,944 microchambers, and it is used to detect red blood cells (RBCs) infected with the causative agent of malaria, Plasmodium. Plasmodium-infected red blood cells (iRBCs) stained with a nuclear staining dye (SYTO 21) form a monolayer on the bottom of the microchambers, and about 130 RBCs are accommodated in each such microchamber of the chip. The iRBCs in the RBC monolayer (containing 2.7 million RBCs) can be identified using a fluorescence detector, and the infection rate can be calculated by counting the number of fluorescent-positive RBCs. This diagnostic device is highly sensitive and hence advantageous for early diagnosis of malaria infections in endemic areas. However, a standard positive control for Plasmodium-infected RBCs is required to ensure that the reagents and detectors of these cell microarray chips are working efficiently in remote endemic areas. Here, we introduce "pseudo-iRBC beads," which consist of a mixture of DEA beads mimicking RBCs and DEA beads coated with nucleic acids mimicking nuclei of the parasite. These beads can be stained with SYTO 21, applied onto the cell microarray chip to form a monolayer, and detected using the fluorescence detector in the same way as iRBCs. Therefore, the introduction of pseudo-iRBC beads as a positive control ensures unbiased malaria diagnoses with the cell microarray chip device in remote endemic areas.
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Affiliation(s)
- Muneaki Hashimoto
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Masahiko Numata
- 2 National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8563, Japan
| | - Shouki Yatsushiro
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Yusuke Ido
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Masato Tanaka
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Kazuaki Kajimoto
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
| | - Masatoshi Kataoka
- 1 Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0301, Japan
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Izumi S, Yamamura S, Hayashi N, Toma M, Tawa K. Dual-Color Fluorescence Imaging of EpCAM and EGFR in Breast Cancer Cells with a Bull's Eye-Type Plasmonic Chip. SENSORS 2017; 17:s17122942. [PMID: 29257118 PMCID: PMC5751630 DOI: 10.3390/s17122942] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/11/2017] [Accepted: 12/15/2017] [Indexed: 01/05/2023]
Abstract
Surface plasmon field-enhanced fluorescence microscopic observation of a live breast cancer cell was performed with a plasmonic chip. Two cell lines, MDA-MB-231 and Michigan Cancer Foundation-7 (MCF-7), were selected as breast cancer cells, with two kinds of membrane protein, epithelial cell adhesion molecule (EpCAM) and epidermal growth factor receptor (EGFR), observed in both cells. The membrane proteins are surface markers used to differentiate and classify breast cancer cells. EGFR and EpCAM were detected with Alexa Fluor® 488-labeled anti-EGFR antibody (488-EGFR) and allophycocyanin (APC)-labeled anti-EpCAM antibody (APC-EpCAM), respectively. In MDA-MB231 cells, three-fold plus or minus one and seven-fold plus or minus two brighter fluorescence of 488-EGFR were observed on the 480-nm pitch and the 400-nm pitch compared with that on a glass slide. Results show the 400-nm pitch is useful. Dual-color fluorescence of 488-EGFR and APC-EpCAM in MDA-MB231 was clearly observed with seven-fold plus or minus two and nine-fold plus or minus three, respectively, on the 400-nm pitch pattern of a plasmonic chip. Therefore, the 400-nm pitch contributed to the dual-color fluorescence enhancement for these wavelengths. An optimal grating pitch of a plasmonic chip improved a fluorescence image of membrane proteins with the help of the surface plasmon-enhanced field.
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Affiliation(s)
- Shota Izumi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyōgo 669-1337, Japan.
| | - Shohei Yamamura
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan.
| | - Naoko Hayashi
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan.
| | - Mana Toma
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyōgo 669-1337, Japan.
| | - Keiko Tawa
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyōgo 669-1337, Japan.
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Hashimoto M, Yatsushiro S, Yamamura S, Tanaka M, Sakamoto H, Ido Y, Kajimoto K, Bando M, Kido JI, Kataoka M. Hydrophilic-treated plastic plates for wide-range analysis of Giemsa-stained red blood cells and automated Plasmodium infection rate counting. Malar J 2017; 16:321. [PMID: 28789644 PMCID: PMC5549322 DOI: 10.1186/s12936-017-1975-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/04/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is a red blood cell (RBC) infection caused by Plasmodium parasites. To determine RBC infection rate, which is essential for malaria study and diagnosis, microscopic evaluation of Giemsa-stained thin blood smears on glass slides ('Giemsa microscopy') has been performed as the accepted gold standard for over 100 years. However, only a small area of the blood smear provides a monolayer of RBCs suitable for determination of infection rate, which is one of the major reasons for the low parasite detection rate by Giemsa microscopy. In addition, because Giemsa microscopy is exacting and time-consuming, automated counting of infection rates is highly desirable. RESULTS A method that allows for microscopic examination of Giemsa-stained cells spread in a monolayer on almost the whole surface of hydrophilic-treated cyclic olefin copolymer (COC) plates was established. Because wide-range Giemsa microscopy can be performed on a hydrophilic-treated plate, the method may enable more reliable diagnosis of malaria in patients with low parasitaemia burden. Furthermore, the number of RBCs and parasites stained with a fluorescent nuclear staining dye could be counted automatically with a software tool, without Giemsa staining. As a result, researchers studying malaria may calculate the infection rate easily, rapidly, and accurately even in low parasitaemia. CONCLUSION Because the running cost of these methods is very low and they do not involve complicated techniques, the use of hydrophilic COC plates may contribute to improved and more accurate diagnosis and research of malaria.
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Affiliation(s)
- Muneaki Hashimoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan.
| | - Shouki Yatsushiro
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Shohei Yamamura
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Masato Tanaka
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Hirokazu Sakamoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan.,Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - Yusuke Ido
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Kazuaki Kajimoto
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
| | - Mika Bando
- Department of Periodontology and Endodontology, Institute of Health Biosciences, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto, Tokushima, 770-8504, Japan
| | - Jun-Ichi Kido
- Department of Periodontology and Endodontology, Institute of Health Biosciences, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto, Tokushima, 770-8504, Japan
| | - Masatoshi Kataoka
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0301, Japan
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Tawa K, Yamamura S, Sasakawa C, Shibata I, Kataoka M. Sensitive Detection of Cell Surface Membrane Proteins in Living Breast Cancer Cells Using Multicolor Fluorescence Microscopy with a Plasmonic Chip. ACS APPLIED MATERIALS & INTERFACES 2016; 8:29893-29898. [PMID: 27750430 DOI: 10.1021/acsami.6b07777] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A plasmonic chip was applied to live cancer cell imaging. The epithelial cell adhesion molecule (EpCAM) is a surface marker that can be used to classify breast cancer cell lines into distinct differentiation states. EpCAM and the nuclei of two kinds of living breast cancer cells, MDA-MB231 and MCF-7, were stained with allophycocyanin (APC)-labeled anti-EpCAM antibody and 4',6-diamidino-2-phenylindole (DAPI), respectively, and the cells were scattered on either a plasmonic chip (metal-coated wavelength-scale grating substrate) or a control glass slide. Multicolor fluorescence microscopic imaging allowed fluorescence images of APC-EpCAM to be obtained on the plasmonic chip that were more than 10 times brighter compared with those on the glass slide. In contrast, in the fluorescence images of DAPI-stained nuclei, no difference in brightness was observed between substrates. The fluorescence enhancement of APC-EpCAM in the cell membrane in contact with the plasmonic chip is thought to be due to the excitation of APC molecules localized within the surface plasmon field. Analysis of the cross section of a fluorescence image revealed a distribution of EpCAM at a higher level of fluorescence in the center of the cell image because of contact between the cell membrane and the plasmonic chip. In contrast, fluorescence images of APC-EpCAM taken on a glass slide were so dark that only the outline of the cell was characterized. The plasmonic chip thus constitutes a simple and powerful tool for analyzing the distribution and kinetics of surface marker proteins in cell membranes contacting the chip.
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Affiliation(s)
- Keiko Tawa
- Kwansei Gakuin University , 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
- AIST , 1-8-31 Midorigaoka, Ikeda, Osaka 563-8377, Japan
| | - Shohei Yamamura
- AIST , 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Chisato Sasakawa
- Kwansei Gakuin University , 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
- AIST , 1-8-31 Midorigaoka, Ikeda, Osaka 563-8377, Japan
| | - Izumi Shibata
- AIST , 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
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Sawada T, Araki J, Yamashita T, Masubuchi M, Chiyoda T, Yunokawa M, Hoshi K, Tao S, Yamamura S, Yatsushiro S, Abe K, Kataoka M, Shimoyama T, Maeda Y, Kuroi K, Tamura K, Sawazumi T, Minami H, Suda Y, Koizumi F. Prognostic Impact of Circulating Tumor Cell Detected Using a Novel Fluidic Cell Microarray Chip System in Patients with Breast Cancer. EBioMedicine 2016; 11:173-182. [PMID: 27495793 PMCID: PMC5049925 DOI: 10.1016/j.ebiom.2016.07.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/30/2016] [Accepted: 07/22/2016] [Indexed: 12/13/2022] Open
Abstract
Various types of circulating tumor cell (CTC) detection systems have recently been developed that show a high CTC detection rate. However, it is a big challenge to find a system that can provide better prognostic value than CellSearch in head-to-head comparison. We have developed a novel semi-automated CTC enumeration system (fluidic cell microarray chip system, FCMC) that captures CTC independently of tumor-specific markers or physical properties. Here, we compared the CTC detection sensitivity and the prognostic value of FCMC with CellSearch in breast cancer patients. FCMC was validated in preclinical studies using spike-in samples and in blood samples from 20 healthy donors and 22 breast cancer patients in this study. Using spike-in samples, a statistically higher detection rate (p = 0.010) of MDA-MB-231 cells and an equivalent detection rate (p = 0.497) of MCF-7 cells were obtained with FCMC in comparison with CellSearch. The number of CTC detected in samples from patients that was above a threshold value as determined from healthy donors was evaluated. The CTC number detected using FCMC was significantly higher than that using CellSearch (p = 0.00037). CTC numbers obtained using either FCMC or CellSearch had prognostic value, as assessed by progression free survival. The hazard ratio between CTC + and CTC − was 4.229 in CellSearch (95% CI, 1.31 to 13.66; p = 0.01591); in contrast, it was 11.31 in FCMC (95% CI, 2.245 to 57.0; p = 0.000244). CTC detected using FCMC, like the CTC detected using CellSearch, have the potential to be a strong prognostic factor for cancer patients.
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Affiliation(s)
- Takeshi Sawada
- Department of Medical Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan; Department of Medical Oncology/Hematology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Jungo Araki
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Toshinari Yamashita
- Department of Breast Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan
| | - Manami Masubuchi
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Tsuneko Chiyoda
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Mayu Yunokawa
- Department of Breast Oncology and Medical Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Kumiko Hoshi
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Shoichi Tao
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Shohei Yamamura
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Shouki Yatsushiro
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Kaori Abe
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Masatoshi Kataoka
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan
| | - Tatsu Shimoyama
- Department of Medical Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan
| | - Yoshiharu Maeda
- Department of Medical Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan
| | - Katsumasa Kuroi
- Department of Breast Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan
| | - Kenji Tamura
- Department of Breast Oncology and Medical Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Tsuneo Sawazumi
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Hironobu Minami
- Department of Medical Oncology/Hematology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Yoshihiko Suda
- Konica Minolta, Inc., 1 Sakuramachi, Hino, Tokyo 191-8511, Japan
| | - Fumiaki Koizumi
- Division of Clinical Research Support, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan.
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Jonczyk R, Kurth T, Lavrentieva A, Walter JG, Scheper T, Stahl F. Living Cell Microarrays: An Overview of Concepts. MICROARRAYS (BASEL, SWITZERLAND) 2016; 5:E11. [PMID: 27600077 PMCID: PMC5003487 DOI: 10.3390/microarrays5020011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/09/2016] [Accepted: 05/11/2016] [Indexed: 02/06/2023]
Abstract
Living cell microarrays are a highly efficient cellular screening system. Due to the low number of cells required per spot, cell microarrays enable the use of primary and stem cells and provide resolution close to the single-cell level. Apart from a variety of conventional static designs, microfluidic microarray systems have also been established. An alternative format is a microarray consisting of three-dimensional cell constructs ranging from cell spheroids to cells encapsulated in hydrogel. These systems provide an in vivo-like microenvironment and are preferably used for the investigation of cellular physiology, cytotoxicity, and drug screening. Thus, many different high-tech microarray platforms are currently available. Disadvantages of many systems include their high cost, the requirement of specialized equipment for their manufacture, and the poor comparability of results between different platforms. In this article, we provide an overview of static, microfluidic, and 3D cell microarrays. In addition, we describe a simple method for the printing of living cell microarrays on modified microscope glass slides using standard DNA microarray equipment available in most laboratories. Applications in research and diagnostics are discussed, e.g., the selective and sensitive detection of biomarkers. Finally, we highlight current limitations and the future prospects of living cell microarrays.
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Affiliation(s)
- Rebecca Jonczyk
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
| | - Tracy Kurth
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
| | - Antonina Lavrentieva
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
| | - Johanna-Gabriela Walter
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
| | - Thomas Scheper
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
| | - Frank Stahl
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, Hannover 30167, Germany.
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Dittrich P, Ibáñez AJ. Analysis of metabolites in single cells-what is the best micro-platform? Electrophoresis 2015; 36:2196-2206. [PMID: 25929796 DOI: 10.1002/elps.201500045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/04/2015] [Accepted: 04/04/2015] [Indexed: 11/11/2022]
Abstract
This review covers new innovations and developments in the field of single-cell level analysis of metabolites, involving the role of microfluidic and microarray platforms to manipulate and handle the cells prior their detection. Microfluidic and microarray platforms have shown great promise. The latest developments demonstrate their potential to identify a particular cell or even an ensemble of cells (sharing a common property or phenotype) that co-exist in a much larger cell population. The reason for this is the capability of these platforms to perform several complex analytical processes, such as: cleanup, sorting, derivatization, separation, and detection, with great robustness, speed, and reduced sample/reagent consumption. Here, we present several examples that illustrate the rapid strides that have been made for the routine analysis of metabolites by coupling different microfluidics and microarrays devices to a wide range of analytical detectors (e.g. fluorescent microscopy, electrochemical, and mass spectrometry). Herein, we also present selected examples detailing the use of microfluidics and microarrays in the visualization of the natural occurring cell-to-cell heterogeneity in isogenic populations, in particular during the response to external cues. The possibility to accurate monitor the cell-to-cell heterogeneity based on different levels of key metabolites is of clinical relevance, since cell-to-cell heterogeneity can influence, for example, the outcome of a drug treatment.
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Affiliation(s)
- Petra Dittrich
- ETH Zurich - Chemie und Angewandte Biowissenschaften, Wolfgang-Pauli-Str. 10, Zurich, 8093, Switzerland
| | - Alfredo J Ibáñez
- ETH Zurich - Department of Chemistry and Applied Biosciences, Vladimir-Prelog-weg 3, Zurich, 8093, Switzerland
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15
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Morimoto A, Mogami T, Watanabe M, Iijima K, Akiyama Y, Katayama K, Futami T, Yamamoto N, Sawada T, Koizumi F, Koh Y. High-Density Dielectrophoretic Microwell Array for Detection, Capture, and Single-Cell Analysis of Rare Tumor Cells in Peripheral Blood. PLoS One 2015; 10:e0130418. [PMID: 26107884 PMCID: PMC4480363 DOI: 10.1371/journal.pone.0130418] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/20/2015] [Indexed: 12/17/2022] Open
Abstract
Development of a reliable platform and workflow to detect and capture a small number of mutation-bearing circulating tumor cells (CTCs) from a blood sample is necessary for the development of noninvasive cancer diagnosis. In this preclinical study, we aimed to develop a capture system for molecular characterization of single CTCs based on high-density dielectrophoretic microwell array technology. Spike-in experiments using lung cancer cell lines were conducted. The microwell array was used to capture spiked cancer cells, and captured single cells were subjected to whole genome amplification followed by sequencing. A high detection rate (70.2%–90.0%) and excellent linear performance (R2 = 0.8189–0.9999) were noted between the observed and expected numbers of tumor cells. The detection rate was markedly higher than that obtained using the CellSearch system in a blinded manner, suggesting the superior sensitivity of our system in detecting EpCAM− tumor cells. Isolation of single captured tumor cells, followed by detection of EGFR mutations, was achieved using Sanger sequencing. Using a microwell array, we established an efficient and convenient platform for the capture and characterization of single CTCs. The results of a proof-of-principle preclinical study indicated that this platform has potential for the molecular characterization of captured CTCs from patients.
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Affiliation(s)
- Atsushi Morimoto
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Toshifumi Mogami
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Masaru Watanabe
- Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan
| | - Kazuki Iijima
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Yasuyuki Akiyama
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Koji Katayama
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Toru Futami
- Life Science Research Laboratory, Tosoh Corporation, Kanagawa, Japan
| | - Nobuyuki Yamamoto
- Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan
| | - Takeshi Sawada
- Shien-Lab, National Cancer Center Hospital, Tokyo, Japan
| | | | - Yasuhiro Koh
- Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan
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Abstract
Unprecedented access to the biology of single cells is now feasible, enabled by recent technological advancements that allow us to manipulate and measure sparse samples and achieve a new level of resolution in space and time. This review focuses on advances in tools to study single cells for specific areas of biology. We examine both mature and nascent techniques to study single cells at the genomics, transcriptomics, and proteomics level. In addition, we provide an overview of tools that are well suited for following biological responses to defined perturbations with single-cell resolution. Techniques to analyze and manipulate single cells through soluble and chemical ligands, the microenvironment, and cell-cell interactions are provided. For each of these topics, we highlight the biological motivation, applications, methods, recent advances, and opportunities for improvement. The toolbox presented in this review can function as a starting point for the design of single-cell experiments.
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17
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Semi-circular microgrooves to observe active movements of individual Navicula pavillardii cells. J Microbiol Methods 2013; 92:349-54. [DOI: 10.1016/j.mimet.2013.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/10/2013] [Accepted: 01/10/2013] [Indexed: 11/20/2022]
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18
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Eyer K, Stratz S, Kuhn P, Küster SK, Dittrich PS. Implementing Enzyme-Linked Immunosorbent Assays on a Microfluidic Chip To Quantify Intracellular Molecules in Single Cells. Anal Chem 2013; 85:3280-7. [DOI: 10.1021/ac303628j] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- K. Eyer
- Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10,
CH-8093 Zurich, Switzerland
| | - S. Stratz
- Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10,
CH-8093 Zurich, Switzerland
| | - P. Kuhn
- Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10,
CH-8093 Zurich, Switzerland
| | - S. K. Küster
- Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10,
CH-8093 Zurich, Switzerland
| | - P. S. Dittrich
- Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10,
CH-8093 Zurich, Switzerland
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