Method and device for detecting antigen-specific antibodies in a biological fluid sample by using neodymium magnets

Abstract

Methods for detecting antigen-specific antibodies in a biological sample are described. The disclosed methods can be used for the diagnosis of a variety of autoimmune and infectious diseases. The methods use a neodymium magnet to efficiently isolate immune complexes. The disclosed methods are rapid, highly specific and sensitive, require very small volumes of biological sample, and do not require the use of radioactivity. With these advantageous features, the disclosed methods are amendable for point-of-care testing (POCT), which is currently not available for the detection of autoantibodies associated with autoimmune disease or for the detection of many pathogen-specific antibodies.

1 . A device for detecting antigen-specific antibodies in a plurality of biological fluid samples according to a method comprising:
 (i) providing a fusion protein comprising an antigen fused to a light-emitting protein;   (ii) contacting the plurality of biological fluid samples with the fusion protein, thereby forming immune complexes if antigen-specific antibodies are present in the plurality of biological fluid samples;   (iii) contacting the immune complexes with magnetic beads coated with an immunoglobulin-binding protein to form bead-bound immune complexes;   (iv) isolating the bead-bound immune complexes by directly contacting the bead-bound immune complexes with a neodymium magnet; and   (v) detecting emission of light from the isolated bead-bound immune complexes, thereby detecting the presence of antigen-specific antibodies in the plurality of biological fluid samples,   wherein the device comprises a first solid support for housing a plurality of biological fluid samples; and   a second solid support comprising a plurality of neodymium magnets affixed thereto.   
     
     
         2 . The device of  claim 1 , wherein the first solid support comprises a multi-well plate. 
     
     
         3 . The device of  claim 2 , wherein the multi-well plate is a 96-well plate. 
     
     
         4 . The device of  claim 2 , wherein the multi-well plate is a 384-well plate. 
     
     
         5 . The device of  claim 2 , wherein the second solid support comprises the same number of neodymium magnets as the number of wells present in the multi-well plate. 
     
     
         6 . The device of  claim 1 , wherein the neodymium magnets are about 1 cm to about 5 cm in length. 
     
     
         7 . The device of  claim 6 , wherein the neodymium magnets are about 2 cm to about 4 cm in length. 
     
     
         8 . The device of  claim 6 , wherein the neodymium magnets are about 2.5 cm to about 3.5 cm in length. 
     
     
         9 . The device of  claim 1 , wherein the neodymium magnets are less than about 1 mm in diameter. 
     
     
         10 . The device of  claim 9 , wherein the neodymium magnets are about 0.9 mm to about 0.1 mm in diameter. 
     
     
         11 . The device of  claim 9 , wherein the neodymium magnets are about 0.8 mm to about 0.2 mm in diameter. 
     
     
         12 . The device of  claim 9 , wherein the neodymium magnets are about 0.7 mm to about 0.3 mm in diameter. 
     
     
         13 . The device of  claim 9 , wherein the neodymium magnets are about 0.6 mm to about 0.4 mm in diameter. 
     
     
         14 . The device of  claim 1 , which is a hand-held device. 
     
     
         15 . The device of  claim 1 , wherein the total volume of each of the plurality of biological fluid samples is no more than 10 μL. 
     
     
         16 . The device of  claim 15 , wherein the total volume of each of the plurality of biological fluid samples is no more than 2 μL.