Systems and methods for sensing analytes in GMR-based detection of biomarkers

A method of detecting the presence of one or more analytes in one or more query samples in a multiplex detection scheme, the method comprising:

• (a) providing at least two spatially disposed giant magnetoresistance (GMR) sensors, wherein at least two of the GMR sensors comprise a first GMR sensor with a first number of double-stranded DNA molecules disposed on a functionalized surface of the first GMR sensor and a second GMR sensor with a second number of double-stranded DNA molecules disposed on a functionalized surface of the second GMR sensor, wherein:
• the first number of double-stranded DNA molecules includes a first nucleic acid and a second nucleic acid bound to the first nucleic acid and being bound to a first member of a first binding pair;
• and
• the second number of double-stranded DNA molecules includes a first additional nucleic acid and a second additional nucleic acid bound to the first additional nucleic acid and being bound to a first additional member of a second binding pair different from the first binding pair;
• (b) passing magnetic particles over the at least two GMR sensors after passing the one or more query samples over the at least two GMR sensors;
• and
• (c) detecting the presence of at least one of the one or more analytes in the one or more query samples by measuring magnetoresistance change of at least one of the at least two GMR sensors based on determining magnetoresistance before and after passing magnetic particles over the at least two GMR sensors.

A method of amplifying a detection signal for detecting the presence of an analyte in a query sample, the method comprising:

• providing a sensor comprising double stranded DNA molecules disposed on a functionalized surface of a giant magnetoresistance (GMR) sensor, the double stranded DNA molecules comprising a first nucleic acid and a second nucleic acid bound to the first nucleic acid and being configured to bind a detection protein, the detection protein also being capable of binding the analyte,
• passing the detection protein over the sensor;
• passing the query sample over the sensor,
• passing a reporter protein over the sensor after passing the query sample over the sensor, the reporter protein capable of binding the detection protein and the reporter protein configured to bind to magnetic nanoparticles;
• passing a plurality of magnetic particles comprising a first member of a binding pair over the sensor after passing the query sample over the sensor, then passing a plurality of magnetic particles comprising a second member of the binding pair over the sensor;
• and
• detecting the presence of the analyte by measuring amplified magnetoresistance change of the GMR sensor based on determining magnetoresistance before and after passing magnetic particles over the sensor;
• thereby amplifying the detection signal.