University of California

Clinical Micro Sensors, Inc.

Kevin W Plaxco

Hui Li

Francesco Ricci

Netzahualcoyotl Arroyo Curras

Jon Faiz Kayyem

Alan J Heeger

Ryan J White

Chunhai Fan

Alexis Vallé- Bélisle

Andrew J Bonham

Yi Xiao

Arica Lubin

Philip Dauphin-Ducharme

Di Kang

Gabriel Ortega

Typical electrochemical sensors measure target-induced changes in current output. Such measures of target binding are inconsistent across individual sensors, and furthermore, signal will drift over time when the sensor is deployed for long periods. These shortcomings can be avoided by the novel use of chronoamperometry to measure current decay kinetics as the indicator of target binding. Current decay lifetimes will vary in a concentration dependent manner, but remain stable across individual sensors and over time, allowing for calibration-free operation. By these methods, aptamer based electrochemical sensors and other sensor types may be deployed in vivo for extended periods of time and will provide accurate measurement of target binding without calibration.

Calibration free in-vivo measurement of analytes using electrochemical sensors

Electrochemical sensors have great promise for point-of-care and in vivo measurement of medically relevant molecules. However, the need for calibrating individual sensors limits the practical applicability of these sensing platforms. The invention provides a novel method of operating electrochemical sensors which obviates the need to calibrate individual sensors against a sample of known concentration. The invention exploits the frequency dependence of electrochemical output signals and the dependence of output signals on the inherent electron transfer kinetics of a selected sensor design. By use of signals generated at a nonresponsive frequency, a normalizing output value is generated that accounts for sensor-to-sensor variation and which enables an accurate calculation of target concentration. The scope of the invention also includes pre-calibrated sensors that may be utilized without calibration steps.

Calibration-free measurement with electrochemical biosensors

The invention encompasses novel methods of operating electrochemical sensors such as aptamer-based sensors to analyze complex samples, such as flowing whole blood both in vitro or in vivo. In such environments, electrochemical sensors are often subject to drift, which complicates the interpretation of sensor output in terms of target concentration. The method of the invention utilizes a dual-reporter recognition element that generates a first, sensing current that is responsive to target binding and to environmental factors and a second, reference current that is only affected by environmental factors. The reference current provides information about environmentally-induced drift, which allows the drift effect to be subtracted out. By removing drift artifacts, electrochemical sensors may be deployed to analyze complex samples, such as whole blood, in vivo.

Dual-reporter electrochemical sensors with drift correction

Provided are unimolecular oligonucleotide probes for detecting a target in a sample. The probes use target binding-induced structural changes to detect the presence of the target in the sample. Also provided are methods of using the probes to detect a target in a sample.

Nucleotide-based probes and methods for the detection and quantification of macromolecules and other analytes

A reagentless, reusable bioelectronic DNA, or other oligonucleotide sequence sensor is disclosed. The sensor includes an oligonucleotide (aptamer) probe tagged with a electroactive, redoxable moiety, self-assembled on or near an electrode. This surface-confined oligonucleotide (aptamer) probe structure undergoes hybridization-induced conformational change in the presence of the target which changes the electron-transfer distance between the redoxable moiety and the electrode thereby providing a detectable signal change. In an alternative embodiment, the target can harbor the redoxable moiety.

Reagentless, reusable, bioelectronic detectors

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., 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.

Signal-on architecture for electronic, oligonucleotide-based detectors

A method for detecting the presence of a target analyte comprising binding a target analyte to a binding ligand comprising at least a first electron donor moiety and a second electron acceptor moiety; and detecting the electron transfer between the donor and acceptor, wherein there is a change in the amount of electron transfer between the donor and acceptor as a result of altering the structured state of the donor and acceptor caused by a conformational change in the binding ligand upon binding of the target ligand.

Growing community of inventors

Santa Barbara, CA, United States of America

Kevin W Plaxco