DETECTING ANALYTES

• US 20120285829A1
• Filed: 12/07/2010
• Published: 11/15/2012
• Est. Priority Date: 12/09/2009
• Status: Abandoned Application

• Current Assignee: ITI Scotland Limited (Scottish Government)
• Original Assignee: ITI Scotland Limited (Scottish Government)
• Inventors: Mount, Andrew, Bachmann, Till, Ghazal, Peter, Khondoker, Mizanur, Ciani, Ilenia
• Application Number:
  US13/514,889
• Publication Number:
  US 20120285829A1
• Time in Patent Office: Days
• US Class Current: 204/450
• CPC Class Codes: C12Q 1/6883 for diseases caused by alterations of genetic material
• CPC Class Codes: C12Q 2600/118 Prognosis of disease development
• CPC Class Codes: G01N 27/026 Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01N 27/3277 being a redox reaction, e.g. detection by cyclic voltammetry voltammetry per se G01N27/42, G01N27/48
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: G01N 33/582 with fluorescent label
• CPC Class Codes: G01N 33/585 with a particulate label, e.g. coloured latex

Abstract

Provided is a method for detecting an analyte, which method comprises:

• • a) applying an alternating voltage to the analyte, wherein the alternating voltage comprises a plurality of superimposed frequencies sufficient to distinguish the presence of the analyte by electrochemical impedance spectrometry (EIS); and
  • b) determining the identity and/or quantity of the analyte from EIS data.

Claims

1. A method for detecting an analyte, which method comprises:

a) applying an alternating voltage to the analyte, wherein the alternating voltage comprises a plurality of superimposed frequencies sufficient to distinguish the presence of the analyte by electrochemical impedance spectrometry (EIS); and

b) determining the identity and/or quantity of the analyte from EIS data;

wherein the plurality of frequencies is determined prior to step (a) by empirical methods, and includes at least a minimum number of frequencies to detect the analyte, so as to increase assay speed.

2. A method according to claim 1, wherein the EIS data comprises data parameters derived from the complex impedance (x+iy), which parameters are selected from one or more of the following:

Real component (x)

Imaginary component (y)

Modulus or absolute value [r=|z|=(x²+y²)^1/2]

Angle [θ

=tan−

1(y/x)]

Principal component 1

Principal component 2

4. A method according to claim 1, wherein the minimum number of superimposed frequencies is from 2-20.

5. A method according to claim 4, wherein the number of superimposed frequencies is at least 3-10.

6. A method according to claim 5, wherein the number of superimposed frequencies is at least 7.

7. A method according to any prcccding claim 1, wherein step (b) comprises a step of performing a Fourier transform on the EIS data.

14. A method according to claim 1 or 8, wherein a liquid medium is employed to aid in EIS measurement.

15. A method according to claim 14, wherein the liquid medium comprises H₂SO₄.

16. A method according to claim 1 or 8, wherein the method is for analysing two or more analytes, and further comprises the step of labelling each analyte with one or more labels to form labelled analytes distinguishable from each other by their labels.

17. A method according to claim 16, wherein the one or more labels are suitable for optical and/or electrical detection.

18. A method according to claim 17, wherein the labels are selected from nanoparticles, single molecules, chemiluminescent enzymes and fluorophores.

19. A method according to claim 18, wherein the labels are nanoparticles comprising a collection of molecules and/or atoms.

20. A method according to claim 19, wherein the nanoparticles are selected from metals, metal nanoshells, metal binary compounds and quantum dots.

21. A method according to claim 20, wherein the nanoparticles are metal compounds selected from CdSe, ZnS, CdTe, CdS, PbS, PbSe, Hgl, ZnTe, GaAs, HgS, CdAs, CdP, ZnP, AgS, InP, GaP, GaInP, and InGaN.

22. A method according to claim 21, wherein the nanoparticles are selected from gold, silver, copper, cadmium, selenium, palladium and platinum.

23. A method according to claim 18, wherein the nanoparticles are less than 100 nm in diameter.

24. A method according to claim 1 or 8, wherein the optical detection method is selected from optical emission detection, optical absorbance detection, optical scattering detection, spectral shift detection, surface plasmon resonance imaging, and surface-enhanced Raman scattering from adsorbed dyes.

25. A method according to claim 24, wherein the optical detection is optical emission detection and comprises the steps of irradiating the labelled analytes with light capable of exciting the labels and detecting the frequency and intensity of light emissions from the labels.

26. A method according to claim 25, wherein the light is laser light.

27. A method according to claim 25, wherein the light is selected from infra-red light, visible light and UV light.

28. A method according to claim 27, wherein the light is white light.

29. A method according to claim 1 or 8, wherein the analyte comprises one or more compounds selected from a cell, a protein, a polypeptide, a peptide, a peptide fragment, an amino acid, DNA and RNA.

30. A method according to claim 29, wherein the analyte is a protease, preferably a protease associated with impaired wound healing, more preferably MM8 or MM9.

31. A method according to claim 30, wherein the analyte is detected using impedimetric protease activity detection.

32. A method of detecting impaired wound healing, which method comprises performing a protease detection method as defined in claim 30 or claim 31.

3. (canceled)

8. A method for detecting an analyte, which method comprises:

a) applying an alternating voltage to the analyte;

b) determining the rate of change of electrochemical impedance spectrometry (EIS) measurements across the analyte;

c) determining the identity and/or quantity of the analyte from rate of change data;

wherein step (b) is carried out in real time so as to increase assay speed.

9. A method according to claim 8, wherein the EIS measurements are measurements of electron transfer resistance, R_et.

10. A method according to claim 8, wherein the EIS measurements are measurements calculated from finding the width of the semicircular feature in a Nyquist plot.

11. A method according to claim 8, wherein an electrolyte is added to the system to aid in EIS measurement.

12. A method according to claim 11, wherein the electrolyte is a transition metal complex.

13. A method according to claim 11, wherein the transition metal complex comprises the [Fe(CN)₆]³⁻

/4−

system.