Assays using surface-enhanced raman spectroscopy (SERS)-active particles

1. A method for detecting the presence or amount of one or more analytes in a biological sample, the method comprising:

(a) providing a biological sample suspected of containing one or more analytes;

(b) disposing the biological sample in an assay vessel, wherein the assay vessel:

(i) has disposed therein a reagent comprising

one or more SERS-active nanoparticles having associated therewith at least one specific binding member having an affinity for the one or more analytes and

at least one SERS-active reporter molecule; and

one or more magnetic capture particles,

wherein the one or more magnetic capture particles have associated therewith at least one specific binding member having an affinity for the one or more analytes and at least one reference label capable of generating a detectable signal,

wherein the binding member associated with the SERS-active nanoparticles can be the same or different than the binding member associated with the magnetic capture particles; or

(ii) is adapted to have disposed therein the reagent of step (b)(i), wherein the reagent of step (b)(i) is disposed in the assay vessel prior to, concurrent with, or subsequent to disposing the sample therein;

(c) incubating the biological sample for a period of time to form a magnetic capture particle-analyte-SERS-active nanoparticle complex if the one or more analytes are present in the biological sample;

(d) exposing the magnetic capture particle-analyte-SERS-active nanoparticle complex to a magnetic field to induce the complex to migrate to a localized area of the assay vessel and form a pellet;

(e) illuminating the localized area of the assay vessel with incident radiation at one or more wavelengths to induce the SERS-active nanoparticle to produce a first detectable signal and the reference label to produce a second detectable signal;

(f) measuring the first detectable signal of the SERS-active nanoparticle to detect the presence or amount of the one or more analytes in the biological sample,

(g) measuring the second detectable signal of the reference label; and

(h) correcting the result of step (f) for variations in the pellet shape, density, and/or position by comparing the first detectable signal of the SERS-active nanoparticle to the second detectable signal of the reference label.

2. The method of claim 1 , wherein the reference label comprises a second SERS-active nanoparticle having a different reporter molecule than the one or more SERS-active nanoparticles which form a complex with the one or more analytes.

3. A method for detecting the presence or amount of one or more analytes in a biological sample, the method comprising:

(a) providing a biological sample suspected of containing one or more analytes;

(b) disposing the biological sample in an assay vessel, wherein the assay vessel:

(i) has disposed therein a reagent comprising

a first aliquot of one or more SERS-active reporter molecules capable of producing a detectable signal having associated therewith at least one specific binding member having an affinity for the one or more analytes; and

one or more magnetic capture particles, wherein the one or more magnetic capture particles have associated therewith at least one specific binding member having an affinity for the one or more analytes,

wherein the binding member associated with the SERS-active one or more reporter molecules can be the same or different than the binding member associated with the magnetic capture particles; or

(ii) is adapted to have disposed therein the reagent of step (b)(i), wherein the reagent of step (b)(i) is disposed in the assay vessel prior to, concurrent with, or subsequent to disposing the sample therein;

(c) disposing a second aliquot of one or more reporter molecules capable of producing a detectable signal having associated therewith at least one specific binding member having an affinity for the specific binding member of the first aliquot of SERS-active reporter molecules in the assay vessel prior to, concurrent with, or subsequent to disposing the sample and/or the first aliquot of SERS-active one or more reporter molecules therein, wherein the one or more reporter molecules of the second aliquot of reporter molecules is the same as the one or more SERS-active reporter molecules of the first aliquot of SERS-active reporter molecules;

(d) incubating the biological sample for a period of time to form a magnetic capture particle-analyte-first aliquot SERS-active reporter molecule-second aliquot reporter molecule complex such that at least one of the one or more second aliquot reporter molecules binds to one of the first aliquot SERS-active reporter molecules to provide at least two reporter molecules within the complex if the one or more analytes are present in the biological sample;

(e) exposing the magnetic capture particle-analyte-first aliquot SERS-active reporter molecule-second aliquot reporter molecule complex to a magnetic field to induce the complex to migrate to a localized area of the assay vessel; and

(f) illuminating the localized area of the assay vessel with incident radiation at one or more wavelengths to induce the SERS-active reporter molecules to produce a detectable signal to detect the presence or amount of the one or more analytes in the biological sample.

4. The method of claim 3 , wherein the SERS-active reporter molecule comprises a SERS-active molecule associated with a nanoparticle capable of producing a SERS signal.

5. The method of claim 3 , wherein the specific binding member of the second aliquot of reporter molecules does not recognize the specific binding member of the one or more magnetic capture particles.

6. The method of claim 3 , wherein the analyte is a polynucleotide.

7. The method of any of claim 1 , or 3 , wherein the magnetic field is provided by a magnet wherein the magnet is a permanent magnet or an electromagnet.