Single-particle bridge assay for amplification-free electrical detection of ultralow-concentration biomolecules and non-biological molecules

1. A device, comprising:

an electrically-insulating substrate; and

a first detecting unit, comprising:

a source electrode disposed on the electrically-insulating substrate;

a drain electrode; and

a dielectric layer;

wherein the dielectric layer is disposed between the source electrode and the drain electrode;

wherein the drain electrode and the dielectric layer comprise an array of holes;

wherein the holes in the drain electrode and the dielectric layer are aligned; and

at least one capture unit, comprising:

a capture nanoparticle;

wherein the capture nanoparticle is in contact with the source electrode; and wherein the nanoparticle is substantially centered in the holes of the drain electrode and the dielectric layer;

and wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle.

2. The device of claim 1 , further comprising:

a probe nanoparticle;

wherein the probe nanoparticle forms a nanoparticle-bridge conjugate with the capture nanoparticle in the presence of a target molecule;

wherein the probe nanoparticle in the nanoparticle-bridge conjugate provides an electrical path between the capture nanoparticle and the drain electrode.

3. The device of claim 1 , further comprising:

a first oligonucleotide target;

wherein the capture nanoparticle comprises a first single-stranded oligonucleotide having a first nucleotide sequence complementary to a portion of the first oligonucleotide target; and

wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle; and

a plurality of probe nanoparticles;

wherein the probe nanoparticles comprise at least one nanoparticle and a probe oligonucleotide complementary to at least a portion of the first oligonucleotide target different than the portion complementary to the first nucleotide sequence; and

wherein the probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle.

4. The device of claim 1 , wherein the device further comprises:

a polypeptide target;

wherein the capture nanoparticle comprises a first antibody having an affinity for the polypeptide target; and wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle; and

a plurality of probe nanoparticles;

wherein the probe nanoparticles comprise at least one nanoparticle and a second antibody capable of binding an unbound portion of the polypeptide target; and

wherein the probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle.

5. The device of claim 1 , further comprising:

a target molecule;

wherein the capture nanoparticle comprises a capture molecule having an affinity for the target molecule; and wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle; and

a plurality of probe nanoparticles;

wherein the probe nanoparticles comprise at least one nanoparticle and a probe molecule capable of binding an unbound portion of the target molecule; and

wherein the probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle.

6. The device of claim 1 , further comprising:

a plurality of second detecting units, each second detecting unit comprising:

an electrically-insulating substrate;

a source electrode disposed on the electrically-insulating substrate;

a drain electrode; and

a dielectric layer;

wherein the dielectric layer is disposed between the source electrode and the drain electrode;

wherein the drain electrode and the dielectric layer comprise an array of holes;

wherein the holes in the drain electrode and the dielectric layer are aligned; and

at least one capture unit, comprising:

a capture nanoparticle;

wherein the capture nanoparticle is in contact with the source electrode; and wherein the nanoparticle is substantially centered in the holes of the drain electrode and the dielectric layer.

7. The device of claim 1 , wherein the source electrode is selected from the group consisting of Cr, Ti, Mo, W, Si, GaAs, and InP.

8. The device of claim 7 , wherein the source electrode is chromium (Cr).

9. The device of claim 1 , wherein the drain electrode is selected from the group consisting of gold, silver, titanium, and copper.

10. The device of claim 9 , wherein the drain electrode is gold.

11. The device of claim 1 , wherein the dielectric layer is selected from the group consisting of SiO 2 , Si 3 N 4 , HfO 2 , and Al 2 O 3 .

12. The device of claim 11 , wherein the dielectric layer is SiO 2 .

13. The device of claim 1 , wherein the electrically-insulating substrate is silicon, silicon dioxide, or a combination thereof.

14. The device of claim 13 , wherein the electrically-insulating substrate is silicon dioxide.

15. The device of claim 1 , wherein the source electrode and drain electrode are comprised of different metals.

16. The device of claim 15 , wherein the source electrode is chromium and the drain electrode is gold.

17. The device of claim 1 , further comprising an electrical reading device for interrogating the device.

18. The device of claim 1 , further comprising a portable electrical reading device for interrogating the device.

19. A method of detecting nucleic acid hybridization, comprising:

providing a device of claim 1 ;

providing a first oligonucleotide target;

wherein the capture nanoparticle comprises a first single-stranded oligonucleotide having a first nucleotide sequence complementary to a portion of a first oligonucleotide target;

wherein the first oligonucleotide target hybridizes a portion of the first nucleotide sequence thereby leaving an unhybridized portion of the first oligonucleotide target;

providing a plurality of first probe nanoparticles under hybridizing conditions;

wherein the first probe nanoparticles comprise at least one nanoparticle and a probe oligonucleotide complementary to the unhybridized portion of the first oligonucleotide target;

wherein the nanoparticle in the first probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle;

applying a voltage drop across the electrodes; and

measuring a change in conductivity, resistivity, capacitance, or impedance across the electrodes at known locations to determine complementarity of the oligonucleotide target to the first nucleotide sequence and complementarity of the oligonucleotide target to the probe oligonucleotide sequence.

20. A method of detecting a polypeptide, comprising:

providing a device of claim 1 ;

wherein the capture nanoparticle is comprised of a plurality of first antibodies attached to the nanoparticle; and wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle;

providing a polypeptide target;

wherein the first antibodies have an affinity to a portion of the polypeptide target;

providing a plurality of first probe nanoparticles under hybridizing conditions;

wherein the first probe nanoparticles comprise at least one nanoparticle and a second antibody capable of binding an unbound portion of the polypeptide target;

wherein the probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle; applying a voltage drop across the electrodes; and

measuring a change in conductivity, resistivity, capacitance, or impedance across the electrodes at known locations to determine binding of the polypeptide target to the first antibodies and to determine binding of the polypeptide target to the second antibodies.

21. A method of detecting a non-biological molecule, comprising:

providing a device of claim 1 ;

wherein the capture nanoparticle is comprised of a plurality of first molecules attached to the nanoparticle; and wherein the capture nanoparticle is a metal, semiconductor, or magnetic nanoparticle;

providing a target molecule;

wherein the first molecules have an affinity to a portion of the target molecule;

providing a plurality of first probe nanoparticles under hybridizing conditions;

wherein the first probe nanoparticles comprise at least one nanoparticle and a probe molecule capable of binding an unbound portion of the target molecule;

wherein the probe nanoparticle is a metal, semiconductor, or magnetic nanoparticle; applying a voltage drop across the electrodes; and

measuring a change in conductivity, resistivity, capacitance, or impedance across the electrodes at known locations to determine binding of the target molecule to the first molecule and to determine binding of the target molecule to the probe molecule.