Toxin activity assays, devices, methods and systems therefor

Abstract

Embodiments of the present invention are directed toward devices, system and method for conducting toxin activity assay using sedimentation. The toxin activity assay may include generating complexes which bind to a plurality of beads in a fluid sample. The complexes may include a target toxin and a labeling agent, or may be generated due to presence of active target toxin and/or labeling agent designed to be incorporated into complexes responsive to the presence of target active toxin. The plurality of beads including the complexes may be transported through a density media, wherein the density media has a lower density than a density of the beads and higher than a density of the fluid sample, and wherein the transporting occurs, at least in part, by sedimentation. Signal may be detected from the labeling agents of the complexes.

What is claimed is: 
     
         1 . An apparatus for conducting a toxin activity assay, the apparatus comprising:
 a substrate, wherein the substrate at least in part defines a channel;   a fluid sample contained in the channel, wherein the fluid sample includes a plurality of beads having complexes formed thereon by action of an active toxin, individual ones of the complexes comprising a capture agent and a labeling agent;   a detection region coupled to the channel and defined at least in part by the substrate and containing a density media, wherein the density media has a density higher than a density of the fluid sample and lower than a density of the plurality of beads; and   wherein the channel and detection region are configured to transport the plurality of beads in the fluid sample from the channel through the density media responsive to a centrifugal force, and wherein at least a portion of the free labeling agent is restricted from transport through the density media.   
     
     
         2 . The apparatus of  claim 1 , wherein said complex further comprises a target analyte. 
     
     
         3 . The apparatus of  claim 2 , wherein the target analyte comprises a SEB. 
     
     
         4 . The apparatus of  claim 1 , wherein the active toxin is Ricin. 
     
     
         5 . The apparatus of  claim 1 , wherein the active toxin is Shiga-like toxin. 
     
     
         6 . The apparatus of  claim 1 , wherein the active toxin is a SEB. 
     
     
         7 . The apparatus of  claim 1 , wherein the beads comprise silica beads. 
     
     
         8 . The apparatus of  claim 7 , wherein the beads are linked to major histocompatibility complex II. 
     
     
         9 . The apparatus of  claim 7 , wherein the beads are linked to a DNA or RNA fragment. 
     
     
         10 . The apparatus of  claim 9 , wherein the DNA or RNA fragment comprises a Ricin and/or Sarcin loop. 
     
     
         11 . The apparatus of  claim 1 , wherein the labeling agent comprises Apurinic/apyrimidinic (AP) endonuclease (APE1) enzyme. 
     
     
         12 . The apparatus of  claim 1 , wherein the labeling agent comprises a stained immortalized T-cell line. 
     
     
         13 . The apparatus of  claim 12 , wherein the immortalized T-cell line comprises Jurkat cells. 
     
     
         14 . The apparatus of  claim 13 , wherein the Jurkat cells are fixed. 
     
     
         15 . The apparatus of  claim 14 , wherein the Jurkat cells are stained by acrinidine orange. 
     
     
         16 . The apparatus of  claim 1 , wherein the density media has a density less than a density of the plurality of beads but greater than the fluid sample. 
     
     
         17 . A system for conducting a toxin activity assay, the system comprising:
 a microfluidic disk comprising:
 a substrate, wherein the substrate at least in part defines a channel; 
   
       a fluid sample contained in the channel, wherein the fluid sample includes a plurality of beads having complexes formed thereon by action of an active toxin, individual ones of the complexes comprising a capture agent and a labeling agent, wherein the fluid sample further includes free labeling agent;
 a detection region coupled to the channel and defined at least in part by the substrate and containing a density media, wherein the density media has a density higher than a density of the fluid sample and lower than a density of the plurality of beads; and 
 wherein the channel and detection region are configured to transport the plurality of beads in the fluid sample from the channel through the density media responsive to a centrifugal force, and wherein at least a portion of the free labeling agent is restricted from transport through the density media; 
 a motor coupled to the microfluidic disk, the motor configured to receive a motor control signal and spin the microfluidic disk responsive to the motor control signal; 
 a detection module positioned to detect a signal from labeling agents included in the complexes, wherein the detection module is configured to generate an electronic detection signal based, at least in part, on the signal from the labeling agent; and 
 a processing device coupled to the motor and the detection module, wherein the processing device is configured to generate the motor control signal and provide the motor control signal to the motor, and wherein the processing device is further configured to receive the electronic detection signal from the detection module. 
 
     
     
         18 . The system of  claim 17 , wherein the signal from the labeling agents comprises an optical signal and wherein the detection module comprises a laser and photomultiplier or a laser and photodiode.