Patent FR-2959820-A1 (FR)
Title: Assaying analyte in liquid medium by reaction of analyte with ligands carried by magnetic particles, comprises measuring magnetic field acting on medium, and measuring amplitude of parameter representative of optical property of medium
Inventor: BAUDRY JEAN
IPC: G01N33/543
Filed: 2010-05-10
Abstract: The process for assaying an analyte in a liquid medium by reaction of analyte with ligands carried by magnetic particles, comprises measuring a magnetic field acting on the liquid medium, measuring an amplitude or variation of a parameter that is representative of an optical property and polarimetric properties of the liquid medium and the cutting of the magnetic field for measuring and deducing an analyte concentration in the liquid medium, and applying a first magnetic field having an intensity and an orientation data to the liquid medium. The process for assaying an analyte in a liquid medium by reaction of analyte with ligands carried by magnetic particles, comprises measuring a magnetic field acting on the liquid medium, measuring an amplitude or variation of a parameter that is representative of an optical property and polarimetric properties of the liquid medium and the cutting of the magnetic field for measuring and deducing an analyte concentration in the liquid medium, applying a first magnetic field having an intensity and an orientation data to the liquid medium, applying a second magnetic field having an intensity and/or perpendicular orientation to the liquid medium, measuring the variation of the parameter between two magnetic fields, placing magnetic particles of different categories in the liquid medium, placing two analytes in the liquid medium, measuring a signal due to the orientation of magnetic clusters corresponding to the first and second analytes, and deducing the concentrations of the analytes of variations of signals during analyte-ligand reactions. The analyte-ligand reaction causes the formation of magnetic particle clusters by bridging and by measuring the parameter representative of the optical property of the liquid medium. The step of measuring the parameter is carried out by the application or modification of the magnetic field for a duration of = 1 second. The concentration of the analyte is deduced from the variation of measurement. The magnetic field of reaction is followed by a relaxation period, which is followed by a measurement of the parameter by the application of the magnetic field. A duration of application of the magnetic field of reaction progressively increases. A cutoff duration of the magnetic field of reaction is constant. The categories are differentiated by the particle size and/or magnetic properties. The particles of first and second categories are functionalized with ligands specific to first and second analytes. The process further comprises verifying whether a variation of the parameter takes place due to clusters corresponding to magnetic particles of the second category during the application of magnetic field. The liquid medium contains magnetic particles of a first category functionalized with ligands specific to the analyte to be assayed, and magnetic particles of a second category-functionalized with ligands do not react with the liquid medium and the analyte to be assayed.