Rapid magnetic biosensor

Abstract

The present invention relates to methods and (bio)sensor systems. Herein, magnetic fields are applied in order to transport magnetic particles laterally over a sensor surface with analyte specific probes. The methods of the invention allow the specific binding of magnetic particles to the sensor surface, while aspecific and unbound particles are removed.

1 . A system ( 1 ) comprising a reaction chamber ( 2 ) having a sensor surface ( 5 ) and at least one region outside said sensor surface ( 6 ) and further comprising at least one means for generating one or more magnetic fields ( 3 ), wherein the at least one means for a generating one or more magnetic fields are placed such that one of said magnetic fields has a gradient with a component that is parallel to said sensor surface ( 5 ) and spans said sensor surface ( 5 ) and said at least one region outside the sensor surface ( 6 ). 
     
     
         2 . The system according to  claim 1  wherein the one of said magnetic fields has a gradient with a component perpendicular to said sensor surface ( 5 ) and wherein said component is directed from the reaction chamber ( 2 ) to the sensor surface. 
     
     
         3 . The system according to  claim 1 , wherein the magnetic field is arranged to move magnetic particles ( 7 ) laterally over the sensor surface ( 5 ) to a first region outside the sensor surface ( 6 ). 
     
     
         4 . The system according to  claim 1 , wherein the magnetic field is capable of moving magnetic particles ( 7 ) from a first region outside the sensor surface ( 6 ), laterally over the sensor surface ( 5 ) to a second region outside the sensor surface ( 6 ). 
     
     
         5 . The system according to  claim 4  wherein said magnetic field is applied in one direction. 
     
     
         6 . The system according to  claim 4  wherein said magnetic field is applied once. 
     
     
         7 . The system according to  claim 4 , wherein said first and second regions outside the sensor surface ( 6 ) are the same. 
     
     
         8 . The system according to  claim 1  wherein a dedicated area is provided on a region outside the sensor surface for the application of magnetic particles. 
     
     
         9 . The system according to  claim 1 , further comprising an inlet means for introducing said magnetic particles into the reaction chamber. 
     
     
         10 . The system according to  claim 1 , wherein said one or more means for generating a magnetic field comprises two magnets ( 3  and  3 ′) which are located at opposite sides of the sensor surface ( 5 ). 
     
     
         11 . The system according to  claim 1 , wherein the magnetic field applied during a given time period on the magnetic particles transports said particles further that the distance obtained by Brownian motion. 
     
     
         12 . The system according to  claim 1 , wherein the at least one means for generating one or more magnetic fields is a magnet generating an out of plane field with smaller in-plane components and being located below the sensor surface. 
     
     
         13 . The system according to  claim 1 , wherein said sensor surface ( 5 ) comprises an analyte-specific probe ( 8 ). 
     
     
         14 . The system according to  claim 1 , wherein the dimension of the sensor surface ( 5 ) located between two regions ( 6 ) outside the sensor surface is at least between 10 and 30 micrometer. 
     
     
         15 . The system according to  claim 1  wherein current carrying conductors suitable for attracting particles to the sensor surface ( 5 ) or to a region outside the sensor surface ( 6 ) are absent. 
     
     
         16 . The system according to  claim 13 , wherein said analyte-specific probe ( 8 ) is selected from the group consisting of an oligonucleotide, an antibody or fragment thereof, a lectin, a pharmaceutical compound, a peptide or a protein. 
     
     
         17 . The system according to  claim 1 , further comprising a magnetic-particle detection means for detection of a magnetic property of at least one magnetic particle on the sensor surface. 
     
     
         18 . The system according to  claim 17  wherein said magnetic-particle detection means detects the magnetic field from the at least one particle, or detects the magnetizability of the at least one particle when subjected to a magnetic detection field. 
     
     
         19 . The system according to  claim 17  wherein said magnetic-particle detection means is a magneto-resistive sensor or a Hall sensor. 
     
     
         20 . A disposable cartridge comprising a reaction chamber ( 2 ), a sensor surface ( 5 ) having an analyte-specific probe or an analyte-analogue ( 8 ), said reaction chamber comprising at least one region outside the sensor surface ( 6 ) and at least one means for generating one or more magnetic fields. 
     
     
         21 . A method for quantifying and/or detecting an analyte, comprising the steps of:
 a) providing magnetic particles ( 7 ) to a reaction chamber with a surface sensor ( 5 ) having an analyte-specific probe or an analyte-analogue ( 8 ) and a region outside said sensor surface ( 6 ),   b) applying a magnetic field gradient within said reaction chamber having a component essentially parallel to said sensor surface, whereby said magnetic field moves said magnetic particles laterally over said sensor surface ( 5 ) toward said region outside said sensor surface, and,   c) detecting said magnetic particles bound to said sensor surface.   
     
     
         22 - 28 . (canceled)