Tunable affinity system and method for ferrofluid-based capture assays

Abstract

Devices, methods, and systems are provided for extracting particles from a ferrofluid and for rapid affinity measurements. Such systems may comprise a fluidic channel or chamber configured to include a ferrofluid having a plurality of target particles and background particles. The systems may include a capture region configured to capture at least a portion of the plurality of target particles. In addition, the systems include a first magnetic field generator and a second magnetic field generator. The first magnetic field generator may be arranged proximate to the fluidic channel, the first magnetic field generator being configured to generate a first magnetic field configured to direct the plurality of target particles towards the capture region. The second magnetic field generator can be arranged to be proximate to the capture region, and is further configured to generate an affinity thresholding magnetic field configured to remove background particles from the capture region.

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         23 . A method, comprising:
 receiving or otherwise providing a ferrofluid having a plurality of target particles and background particles in a fluidic channel or chamber;   generating, by a first magnetic field generator, a first magnetic field configured to direct at least a portion of the plurality of target particles towards a capture region located along a first side of the fluidic channel, the capture region functionalized with a plurality of receptor particles configured to capture the plurality of target particles; and   generating an affinity thresholding magnetic field configured to remove background particles from the capture region.   
     
     
         24 . The method of  claim 23 , wherein the affinity thresholding magnetic field is configured to remove background particles captured by at least a first portion of the plurality of receptor particles. 
     
     
         25 . The method of  claim 23 , further comprising detecting target particles captured by a second portion of the plurality of receptor particles. 
     
     
         26 . The method of  claim 23 , wherein the receiving/providing step comprises receiving/providing a flow of the ferrofluid. 
     
     
         27 . The method of  claim 23 , wherein the affinity thresholding magnetic field is further configured to break an affinity bond strength between captured target particles and corresponding capturing receptor particles after removing the background particles from the capture region. 
     
     
         28 . A method, comprising:
 receiving or otherwise providing a ferrofluid configured to receive and/or contain a plurality of target particles in a fluidic channel or chamber;   generating, by a first magnetic field generator, a first magnetic field configured to direct at least a portion of the plurality of target particles towards a capture region located along a first side of the fluidic channel or chamber, the capture region functionalized with a plurality of receptor particles configured to capture the plurality of target particles;   generating an affinity thresholding magnetic field configured to remove target particles captured by the plurality of receptor particles in the capture region, the second magnetic field generator arranged proximate to the fluidic channel; and   detecting a remaining amount of captured target particles after an application of the affinity thresholding magnetic field to remove the captured target particles from the capture region.   
     
     
         29 . The method of  claim 28 , wherein the affinity thresholding magnetic field is configured to remove target particles captured by the plurality of receptor particles in the capture region. 
     
     
         30 . The method of  claim 28 , further comprising detecting a remaining amount of captured target particles after an application of the affinity thresholding magnetic field to remove the captured target particles. 
     
     
         31 . The method of  claim 28 , further comprising determining, based on the remaining amount, an affinity bond strength between a target particle and a receptor particle. 
     
     
         32 . The method of  claim 28 , wherein the receiving/providing step comprises receiving/providing a flow of the ferrofluid. 
     
     
         33 . The method of  claim 28 , wherein determining an affinity bond strength includes determining the remaining amount of captured target particles is less than a predetermined threshold value.