Detection of biospecific interactions using amplified differential time domain spectroscopy signal

• US 20060045807A1
• Filed: 05/22/2003
• Published: 03/02/2006
• Est. Priority Date: 05/23/2002
• Status: Active Grant

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Zhang, Xi-Cheng, Mickan, Samuel Peter, Menikh, Abdellah
• Granted Patent: US 7,368,280 B2
• Time in Patent Office: Days
• US Class Current: 422/82.50
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/3586 by Terahertz time domain spectroscopy [THz-TDS]
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings

Abstract

A method for detecting specific associations between a tethered molecule and an untethered target molecule. The method comprises (1) selecting a tethered molecule; (2) alternately impinging THz radiation onto the tethered molecule and onto a sample including the tethered and untethered target molecules; (3) detecting the radiation impinged on the tethered molecule to form a reference signal and the radiation impinged on the sample to form a sample signal; and (4) comparing the reference signal with the sample signal to generate a specimen signal indicative of an association between the selected tethered and target molecules. The method will detect whether a selected tethered molecule and the desired target exhibit any affinity or, in cases where the affinity is known, will detect the presence of the target molecule in a sample. Also provided is an apparatus for detecting specific associations between a tethered molecule and an untethered target molecule.

Claims

1. A method for detecting specific associations between a tethered molecule and an untethered target molecule, the method comprising:

a) selecting a molecule to serve as the tethered molecule;

b) alternately impinging THz radiation onto the tethered molecule and onto a sample including the tethered molecule and the untethered target molecule;

c) detecting the radiation impinged on the tethered molecule to form a reference signal and the radiation impinged on the sample including the tethered and target molecules to form a sample signal; and

d) comparing the reference signal with the sample signal to generate a specimen signal indicative of an association between the selected tethered and target molecules.

2. The method according to claim 1 wherein the association is a binding affinity between the selected tethered molecule and the target molecule.

3. The method according to claim 1 wherein the association comprises biomolecular interactions selected from the group consisting of covalent bonds, hybridization interactions, hydrogen bonding interactions, hydrophilic interactions, and specific non-covalent bonds.

4. The method according to claim 1 wherein the tethered molecules comprise molecules selected from the group consisting of ligands, receptors, antigens, antibodies, DNA, and RNA.

5. The method according to claim 1 wherein the target molecules comprise molecules selected from the group consisting of ligands, receptors, antigens, antibodies, DNA, and RNA.

6. The method according to claim 1 wherein the association between the tethered molecule and the target is known and wherein the specimen signal is indicative of the presence of the target in the sample.

7. The method according to claim 1 wherein the target is bound onto a signal amplifying medium.

8. The method according to claim 7 wherein the amplifying medium is agarose, gold, or carbon.

9. The method according to claim 1 wherein the step of comparing the reference signal with the sample signal comprises subtracting the reference signal from the sample signal.

10. The method of claim 1 wherein the tethered molecule is biotin and the target molecule is avidin.

11. The method of claim 10 wherein the avidin molecule is bound onto agarose beads and the agarose beads serve to amplify the sample signal.

12. The method of claim 1 wherein the sample is secured on a quartz slide.

13. The method according to claim 1 further comprising tethering a molecule to a surface to form the tethered molecule.

14. The method according to claim 1 wherein the target molecule comprises avidin or biotin.

15. An apparatus for detecting specific associations between a tethered molecule and an untethered target molecule, the apparatus comprising:

a) a THz radiation source emitting a pulsed THz radiation beam along a THz radiation beam path;

b) a source of a pulsed optical radiation probe beam traveling along an optical radiation path;

c) a THz radiation detector located in the THz radiation beam path and in the optical radiation path whereby the THz radiation beam modulates the optical radiation beam to form a modulated optical radiation beam traveling along a modulated optical beam path;

d) a modulated optical beam detector in the modulated beam path for generating an electronic signal indicative of the modulation of the optical beam;

e) a sample holder in the THz radiation beam path ahead of the THz radiation detector, the sample holder adapted to hold and to movably position in the radiation beam path alternately a first and a second sample, the first sample comprising the tethered molecule and selected to provide a reference signal and the second sample containing a combination of the tethered molecule and the target; and

f) electronic signal processing circuitry for comparing detection signals when the first sample is placed in the THz radiation path with detection signals when the second sample is in the THz radiation path.

16. An apparatus for detecting the presence of a target molecule having a known binding affinity to a ligand, the apparatus comprising:

a) a THz radiation source emitting a THz radiation beam along a THz radiation beam path;

b) a source of an optical radiation probe beam traveling along an optical radiation path;

c) a THz radiation detector located in the THz radiation beam path and in the optical radiation path whereby the THz radiation beam modulates the optical radiation beam to form a modulated optical radiation beam traveling along a modulated optical beam path;

d) a modulated optical beam detector in the modulated beam path for generating an electronic signal indicative of the modulation of the optical beam;

e) a sample holder in the THz radiation beam path ahead of the THz radiation detector, the sample holder movably positioned in the radiation beam path to alternately place in the path a first and a second sample; and

f) electronic signal processing circuitry for subtracting the electronic signal indicative of the modulation of the optical beam when the sample holder places the first sample in the THz radiation beam path from the electronic signal indicative of the modulation of the optical beam when the sample holder places the second sample in the THz radiation beam path.