Magnetic nanoparticles, magnetic detector arrays, and methods for their use in detecting biological molecules
View Patent ↗Magnetic nanoparticles and methods for their use in detecting biological molecules are disclosed. The magnetic nanoparticles can be attached to nucleic acid molecules, which are then captured by a complementary sequence attached to a detector, such as a spin valve detector or a magnetic tunnel junction detector. The detection of the bound magnetic nanoparticle can be achieved with high specificity and sensitivity.
1. A spin valve detector array useful for the detection of magnetic nanoparticles, the detector array comprising:
a plurality of detection sites, wherein each of the plurality of detection sites comprise:
a first ferromagnetic layer;
a non-magnetic layer facially contacting the first ferromagnetic layer;
a second ferromagnetic layer facially contacting the non-magnetic layer;
an ultrathin passivation layer facially contacting the second ferromagnetic layer; and
a binding molecule bonded to the passivation layer, wherein the binding molecule is at least one of a nucleic acid, a natural DNA, a synthetic DNA, a natural RNA, a synthetic RNA, a peptide, a protein, an antibody, a lipid, a virus, a polymer, a toxin compound, a pharmaceutical compound, a biohazard compound, or an explosive compound;
a DC bias field source; and
an AC tickling field source.
2. The array of claim 1 , wherein the first ferromagnetic layer comprises Co, Co alloys, Iron, Iron alloys, Fe—N, Fe 3 O 4 , Fe—Zr—Nb—B, Ni, Ni alloys, or mixtures thereof.
3. The array of claim 1 , wherein the first ferromagnetic layer is pinned by an exchange-bias layer or a synthetic ferromagnetic layer.
4. The array of claim 1 , wherein the second ferromagnetic layer comprises Co, Co alloys, Iron, Iron alloys, Fe—N, Fe 3 O 4 , Fe—Zr—Nb—B, Ni, Ni alloys, or mixtures thereof.
5. The array of claim 1 , wherein the passivation layer is about 1 nm to about 10 nm in thickness.
6. The array of claim 1 , wherein the passivation layer comprises gold, tantalum, or glass.
7. The array of claim 1 , further comprising an aperture on the top of the passivation layer to confine the binding molecule.
8. The array of claim 1 , wherein the non-magnetic layer comprises ruthenium, a ruthenium alloy, chromium, a chromium alloy, gold, a gold alloy, a noble metal, a noble metal alloy, or mixtures thereof.
9. The array of claim 1 , wherein each of the detection sites comprises a spin valve detector or detectors with a line width of between about 0.01 μm and about 1 μm.
10. The array of claim 1 , further comprising microfluidic circuits.
11. The array of claim 1 , wherein the ultrathin passivation layer has a thickness of 10 nm or less.
12. The array of claim 1 , further comprising a row decoder, a column decoder, a preamplifier, and at least one current source.
13. The array of claim 1 , further comprising one or more leads disposed under the first ferromagnetic layer.
14. The array of claim 1 , wherein the array comprises a bridge circuit.
15. The array of claim 1 , wherein the detection sites have a magnetoresistance ratio of 5% or more.
16. The array of claim 1 , wherein the AC tickling field source is configured to produce an AC tickling field orthogonal to a DC bias field produced by the DC bias field source.
17. A spin valve detector array useful for the detection of magnetic nanoparticles, the detector array comprising:
a plurality of detection sites, wherein each of the plurality of detection sites comprise:
a first ferromagnetic layer;
a non-magnetic layer facially contacting the first ferromagnetic layer;
a second ferromagnetic layer facially contacting the non-magnetic layer;
an ultrathin passivation layer facially contacting the second ferromagnetic layer; and
a binding molecule bonded to the passivation layer, wherein the binding molecule is at least one of a nucleic acid, a natural DNA, a synthetic DNA, a natural RNA, a synthetic RNA, a peptide, a protein, an antibody, a lipid, a virus, a polymer, a toxin compound, a pharmaceutical compound, a biohazard compound, or an explosive compound; and
a reference detector, wherein the reference detector comprises a polymer coating.