US 7,803,542 B2Granted

Signal-on architecture for electronic, oligonucleotide-based detectors

AssigneeThe Regents of the University of California

InventorsYi Xiao, Arica Lubin, Kevin Plaxco

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Abstract

The invention provides a general “signal-on” architecture for oligonucleotide-based detectors that leads to order of magnitude increases in signal gain and sensitivity as compared to prior art detectors. The detectors of the invention rely on base pairing between two oligonucleotide strands, the sensor strand and the blocker strand. In the ‘off’ position of the detector, i.e., in the absence of target, the blocker strand and sensor strand are base-paired. As shown in FIG. 1, the formation of comparatively rigid, duplex DNA prevents the redox moiety from approaching the electrode surface, thereby suppressing Faradaic currents. When target is added to the system, the target displaces the blocker strand, binds to the sensor strand, liberating the end of the redox-labeled oligonucleotide to produce a flexible element. This, in turn, allows the redox moiety to collide with the electrode surface, producing a readily detectable Faradaic current.

Claims31

Dependent claims

A detector for assessing the presence of a molecular target comprising:

a) an oligonucleotide blocker;
b) an oligonucleotide sensor having:
a first region complementary to a first region of the blocker, which first regions are capable of forming a first double-stranded complex with the blocker,
wherein the first region of the sensor is capable of specifically interacting with the molecular target thereby disrupting the first double-stranded complex;
and
a second region complementary to a second region of the blocker,
wherein the second regions forms a second double-stranded complex that is not disrupted in the presence of the molecular target;
and
c) an electrode capable of detecting redox signals from a redox moiety covalently attached to either the blocker or the sensor, wherein at least one of the sensor and the blocker is covalently attached to the electrode,
wherein when the first double-stranded complex is formed, the redox moiety is in a first state relative to the electrode, and when the first double-stranded complex is disrupted by the molecular target, the redox moiety is in a second state relative to the electrode, wherein the first and second states give rise to distinguishable redox signals detectable by the electrode.

7 more elements

A method for assessing the presence of a molecular target in a sample comprising the steps of:

a) contacting the sample with a detector comprising
i) an oligonucleotide reporter having a redox moiety attached;
ii) an oligonucleotide sensor having:
a first region complementary to a first region of the oligonucleotide reporter, which first regions are capable of forming a first double stranded complex, wherein a complementary oligonucleotide sensor is capable of specifically interacting with the molecular target thereby disrupting the first double stranded complex;
and
a second region complementary to a second region of the oligonucleotide reporter, which second regions are capable of forming a second double stranded complex that is not disrupted in the presence of the molecular target;
and
wherein the oligonucleotide sensor is covalently attached to an electrode;
and
iii) an electrode capable of detecting redox signals from the redox moiety, wherein at least one of the oligonucleotide reporter and the complementary oligonucleotide sensor is covalently attached to the electrode;
and
b) sensing a first redox signal with the detector, wherein the first redox signal is indicative of the presence of the molecular target in the sample.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/564,674Filed 29 Nov 2006 · us provisional application
Priority: 29 Nov 2005
Published: US 2007/0154909 A15 Jul 2007
Granted: 28 Sep 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

C12Q 1/6825
Characterised by the detection means: nucleic acid detection involving sensors
G01N 27/3277
Sensing specific biomolecules, e.g. nucleic acid strands, based on an electrode surface reaction: being a redox reaction, e.g. detection by cyclic…
C12Q
Measuring or testing processes involving enzymes, nucleic acids or microorganisms
G01N
Investigating or analysing materials by determining their chemical or physical properties