Dual range cardiac troponin immunoassay devices and methods using immunosensor and magnetic immunosensor

Abstract

The present invention relates to systems and methods that utilize a combination of immunoassay and magnetic immunoassay techniques to detect an analyte within an extended range of specified concentrations. In particular, a device includes a first immunosensor including an immobilized layer of capture antibodies configured to bind to a first complex of signal antibodies and cardiac troponin such that a second complex of the first complex and the immobilized layer of capture antibodies is localized on or near the first immunosensor. The device further includes a second immunosensor having a magnetic field disposed locally around the second immunosensor. The magnetic field is configured to attract magnetic beads such that a third complex of the first complex and capture antibodies immobilized on the magnetic beads is localized on or near the second immunosensor sensor.

We claim: 
     
         1 . A computer-implemented method comprising:
 measuring a first signal at a first immunosensor from a reaction of a signal agent with a first complex of signal antibodies, cardiac troponin, and capture antibodies immobilized on a surface of the first immunosensor;   measuring a second signal at a second immunosensor from a reaction of the signal agent with a second complex of the signal antibodies, the cardiac troponin, and capture antibodies immobilized on magnetic beads that are localized on or near a surface of the second immunosensor via a magnetic field;   determining a first concentration of the cardiac troponin in a sample from the first signal;   determining a second concentration of the cardiac troponin in the sample from the second signal;   comparing the first concentration and the second concentration to a predetermined crossover concentration point;   when the first concentration is greater than the predetermined crossover concentration point, reporting the first concentration as a final concentration of the cardiac troponin in a first range above about 1000 pg/mL; and   when the second concentration is less than the predetermined crossover concentration point, reporting the second concentration as the final concentration of the cardiac troponin in a second range from about 0 to about 1000 pg/mL.   
     
     
         2 . The method of  claim 1 , wherein the first immunosensor and the second immunosensor are electrochemical immunosensors and the first signal and the second signal are electrochemical signals. 
     
     
         3 . The method of  claim 1 , wherein the signal antibodies are conjugated with an enzyme. 
     
     
         4 . The method of  claim 3 , wherein the enzyme is alkaline phosphatase. 
     
     
         5 . The method of  claim 4 , wherein the signal agent is a phosphorylated molecule configured such that when a phosphate moiety is removed the molecule becomes electroactive. 
     
     
         6 . The method of  claim 1 , wherein the magnetic field is generated by a composite material including a binder and a particulate magnetic material. 
     
     
         7 . The method of  claim 6 , wherein the binder is a polyimide or polyvinyl alcohol (PVA), and the particulate magnetic material is comprised of neodymium iron boron (NdFeB) alloy or aluminum nickel cobalt (AlNiCo) alloy 
     
     
         8 . A system for detecting cardiac troponin in a biological sample, the system comprising:
 one or more processors;   a memory coupled to the one or more processors, the memory storing a plurality of instructions executable by the one or more processors, the plurality of instructions comprising instructions that when executed by the one or more processors cause the one or more processors to perform processing comprising:   measuring a first signal at a first immunosensor from a reaction of a signal agent with a first complex of signal antibodies, cardiac troponin, and capture antibodies immobilized on a surface of the first immunosensor;   measuring a second signal at a second immunosensor from a reaction of the signal agent with a second complex of the signal antibodies, the cardiac troponin, and capture antibodies immobilized on magnetic beads that are localized on or near a surface of the second immunosensor via a magnetic field;   determining a first concentration of the cardiac troponin in a sample from the first signal;   determining a second concentration of the cardiac troponin in the sample from the second signal;   comparing the first concentration and the second concentration to a predetermined crossover concentration point;   when the first concentration is greater than the predetermined crossover concentration point, reporting the first concentration as a final concentration of the cardiac troponin in a first range above about 1000 pg/mL; and   when the second concentration is less than the predetermined crossover concentration point, reporting the second concentration as the final concentration of the cardiac troponin in a second range from about 0 to about 1000 pg/mL.   
     
     
         9 . The system of  claim 8 , wherein the first immunosensor and the second immunosensor are electrochemical immunosensors and the first signal and the second signal are electrochemical signals. 
     
     
         10 . The system of  claim 8 , wherein the signal antibodies are conjugated with an enzyme. 
     
     
         11 . The system of  claim 10 , wherein the enzyme is alkaline phosphatase. 
     
     
         12 . The system of  claim 11 , wherein the signal agent is a phosphorylated molecule configured such that when a phosphate moiety is removed the molecule becomes electroactive. 
     
     
         13 . The system of  claim 8 , wherein the magnetic field is generated by a composite material including a binder and a particulate magnetic material. 
     
     
         14 . The system of  claim 13 , wherein the binder is a polyimide or polyvinyl alcohol (PVA), and the particulate magnetic material is comprised of neodymium iron boron (NdFeB) alloy or aluminum nickel cobalt (AlNiCo) alloy. 
     
     
         15 . A non-transitory computer-readable memory storing a plurality of instructions executable by one or more processors, the plurality of instructions comprising instructions that when executed by the one or more processors cause the one or more processors to perform processing comprising:
 measuring a first signal at a first immunosensor from a reaction of a signal agent with a first complex of signal antibodies, cardiac troponin, and capture antibodies immobilized on a surface of the first immunosensor;   measuring a second signal at a second immunosensor from a reaction of the signal agent with a second complex of the signal antibodies, the cardiac troponin, and capture antibodies immobilized on magnetic beads that are localized on or near a surface of the second immunosensor via a magnetic field;   determining a first concentration of the cardiac troponin in a sample from the first signal;   determining a second concentration of the cardiac troponin in the sample from the second signal;   comparing the first concentration and the second concentration to a predetermined crossover concentration point;   when the first concentration is greater than the predetermined crossover concentration point, reporting the first concentration as a final concentration of the cardiac troponin in a first range above about 1000 pg/mL; and   when the second concentration is less than the predetermined crossover concentration point, reporting the second concentration as the final concentration of the cardiac troponin in a second range from about 0 to about 1000 pg/mL.   
     
     
         16 . The non-transitory computer-readable memory of  claim 15 , wherein the first immunosensor and the second immunosensor are electrochemical immunosensors and the first signal and the second signal are electrochemical signals. 
     
     
         17 . The non-transitory computer-readable memory of  claim 15 , wherein the signal antibodies are conjugated with an enzyme. 
     
     
         18 . The non-transitory computer-readable memory of  claim 17 , wherein the enzyme is alkaline phosphatase. 
     
     
         19 . The non-transitory computer-readable memory of  claim 18 , wherein the signal agent is a phosphorylated molecule configured such that when a phosphate moiety is removed the molecule becomes electroactive. 
     
     
         20 . The non-transitory computer-readable memory of  claim 15 , wherein the magnetic field is generated by a composite material including a binder and a particulate magnetic material, wherein the binder is a polyimide or polyvinyl alcohol (PVA), and wherein the particulate magnetic material is comprised of neodymium iron boron (NdFeB) alloy or aluminum nickel cobalt (AlNiCo) alloy.