# US 2019/0170758 A1 · Method of detection with a fluorescent labeling particle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170758 A1 - Document ID: US20190170758A1 - Status: Published application - Kind: A1 - Application number: 16/267,107 - Filed: 2019-02-04 - Published: 2019-06-06 - Earliest claimed: 2013-10-02 - Assignees: Furukawa Electric Co., Ltd. - Applicants: Furukawa Electric Co., Ltd. - Inventors: Masataka NISHIDA; Michio OHKUBO; Kazutomi MIYOSHI; Masayuki FUKUSHIMA - Web page: https://patentgrep.com/patent/US20190170758A1 ## CPC - G01N 33/582: {with fluorescent label} - B03C 1/00: Magnetic separation - C09K 11/02: Use of particular materials as binders, particle coatings or suspension media therefor - C09K 11/025: {non-luminescent particle coatings or suspension media} - C09K 11/06: containing organic luminescent materials - G01N 21/6428: {Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" (in vivo A61B5/00; immunoassay G01N33/53)} - G01N 33/54326: {Magnetic particles} - G01N 33/54333: {Modification of conditions of immunological binding reaction, e.g. use of more than one type of particle, use of chemical agents to improve binding, choice of incubation time or application of magnetic field during binding reaction} - G01N 33/5434: {using magnetic particle immunoreagent carriers which constitute new materials per se} - G01N 33/552: Glass or silica - H01F 1/0054: {Coated nanoparticles, e.g. nanoparticles coated with organic surfactant} - B03C 1/01: by addition of magnetic adjuvants - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B) - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract A fluorescent labeling particle for detecting a target substance, containing a composite particle having a phase containing a magnetic material and a phase containing a fluorescent material, and a thermoresponsive polymer on a surface of the composite particle. ## Claims ### Claim 1 A method of detecting a target substance, which comprises: mixing an analyte, a fluorescent labeling particle (A), and a dispersant (B) to form a complex by binding the fluorescent labeling particle and the dispersant via a target substance in the analyte, wherein the fluorescent labeling particle (A) comprises: a phase comprising a magnetic material, a phase comprising a fluorescent material which is constituted of a continuous phase formed of a transparent material including a silica and a dispersed phase formed of the fluorescent material, said phase is coating the phase comprising the magnetic material, a thermoresponsive polymer immobilized on the phase comprising a fluorescent material, and a binding substance having properties of binding with the target substance immobilized on the thermoresponsive polymer; and the dispersant (B) comprising a dispersant base and a binding substance having properties of binding with the target substance. ### Claim 2 (depends on 1) The method of detecting a target substance according to claim 1, wherein the binding substance having properties of binding with the target substance is an antibody. ### Claim 3 (depends on 1) The method of detecting a target substance according to claim 1, wherein the phase comprising a magnetic material forms a core of the fluorescent labeling particle, and the phase comprising a fluorescent material forms a coating on the core. ### Claim 4 (depends on 1) The method of detecting a target substance according to claim 1, wherein the thermoresponsive polymer causes a change in morphologies thereof at a critical solution temperature (CST) as a border, and aggregation properties of the labeling particle change at the critical solution temperature (CST) as the border. ### Claim 5 (depends on 4) The method of detecting a target substance according to claim 4, wherein the thermoresponsive polymer aggregates at temperatures above the critical solution temperature (CST), and disperse at temperatures at or below the critical solution temperature (CST), and wherein the critical solution temperature (CST) is in the range of 10° C. to 100° C. ### Claim 6 (depends on 1) The method of detecting a target substance according to claim 1, wherein an average particle diameter of a composite particle is less than 1 μm, wherein the composite particle comprises a phase comprising the magnetic material, and a phase comprising a fluorescent material which comprises a continuous phase formed of a transparent material including the silica and a dispersed phase formed of the fluorescent material, said phase is coating the phase comprising the magnetic material. ### Claim 7 (depends on 1) The method of detecting a target substance according to claim 1, wherein the magnetic material comprises magnetite, nickel oxide, ferrite, cobalt iron oxide, barium ferrite, carbon steel, tungsten steel, KS steel, a rare earth cobalt magnet or hematite. ### Claim 8 (depends on 1) The method of detecting a target substance according to claim 1, wherein the dispersant base comprises a hydrophilic high molecular weight compound.