Single molecule detection using molecular motors

A method for detecting at least one target nucleic acid comprising:

• (a) providing at least one set of first and second target-specific nucleic acids, wherein the at least one set of first and second target-specific nucleic acids each comprise nucleotide sequences complementary to a specific one of the at least one target nucleic acid;
• wherein each of the at least one set of first and second target-specific nucleic acids are specific only for a selected one of the at least one target nucleic acid;
• wherein each first target-specific nucleic acid is bound to a selected first affinity tag and each second target-specific nucleic acid is bound to a selected second affinity tag, wherein the selected first affinity tag is capable of binding specifically to a molecular motor, wherein the molecular motor is a biological or synthetic molecule capable of induced translational or rotational movements that are capable of being detected, wherein the selected second affinity tag is capable of binding specifically to a metal nanorod detection probe;
• (b) contacting the at least one set of first and second target-specific nucleic acids to a sample under conditions whereby the at least one set of first and second target-specific nucleic acids will only hybridize to the at least one target nucleic acid if the at least one target nucleic acid is present in the sample, wherein the target nucleic acid and the first and second target-specific nucleic acids' nucleotide-base-pairing-specific-ligation reaction requires formation of juxtaposed 5′ phosphate and 3′ hydroxyl termini of two adjacent target-specific nucleic acids which are hybridized to the complementary target nucleic acid to form a nucleic acid strand that contains a first affinity tag and a second affinity tag at the 5′ and 3′ ends respectively;
• (c) upon hybridization to the at least one target nucleic acid, ligating the first and second target-specific nucleic acids together;
• (d) binding a series of molecular motors on a solid support either before or after assembly with nucleic acid containing affinity tags on the 5′ and 3′ ends:
• (e) binding at least one of the series of molecular motors to the selected first affinity tag;
• (f) binding the metal nanorod detection probe to the selected second affinity tag of the molecular motor-target nucleotide complex either before or after the series of molecular motors is bound to the solid support;
• (g) inducing translational or rotational movement of at least one of the molecular motors;
• and
• (h) detecting translational or rotational movement of the at least one molecular motor coupled to the solid support as indicated by detecting changes in light intensity of at least one wavelength originating from the metal nanorod detection probe, where the at least one wavelength indicates the presence of a specific target nucleic acid in the sample, or by observing the metal nanorod detection probe translationally moving wherein differing selected colors of each of the translationally moving metal nanorod detection probes indicate the presence of a unique corresponding target nucleic acid in the sample.