US-12618833-B2 - Sensing of molecules by electrochemical detection of nanoparticles

US12618833B2US 12618833 B2US12618833 B2US 12618833B2US-12618833-B2

Abstract

The invention relates to a method for sensing target molecules in an analyte solution, a sensor for sensing target molecules in an analyte solution and a measurement system for sensing target molecules in an analyte solution. The method comprises providing a capture surface, wherein a plurality of capture molecules are arranged on the capture surface, each of the capture molecules being configured to bind to at least one of said target molecules. The method further comprises exposing the capture surface to the analyte solution to allow target molecules to bind to the capture molecules arranged on the capture surface. The capture surface is then exposed to a solution containing detection molecules, wherein each of the detection molecules contains an electrochemically active nanoparticle and is configured to bind to one of said target molecules bound to a capture molecule, thereby allowing said electrochemically active nanoparticles to bind to the capture surface through formation of a bond between the respective detection molecule comprising said nanoparticle and one of said target molecules bound to one of said capture molecules arranged on the capture surface. The method further comprises releasing nanoparticles that are bound to the capture surface and, after releasing said nanoparticles from the capture surface, determining an electrical signal at a detection electrode caused by electrochemical reactions of said nanoparticles released from the capture surface.

Inventors

Bernhard Wolfrum
Nouran Yehia Adly Hassan
Philipp RINKLIN
Leroy GROB
Oliver Hayden
Lennart Weiß
Phu Duy TRAN
Benjamin THIERRY

Assignees

Technische Universität München

Dates

Publication Date: 20260505
Application Date: 20210115
Priority Date: 20200117

Claims (5)

1 . A measurement system for sensing target molecules in an analyte solution using a sensor comprising a capture surface and a detection electrode, the measurement system comprising: an ammeter configured to measure a current through the detection electrode; and a controller for controlling the ammeter, wherein the controller is configured to: initiate a dissociation process to release electrochemically active nanoparticles adsorbed on the capture surface; determine a measurement signal characterizing the current through the detection electrode as a function of time using the ammeter after initiating the dissociation process; and determine a number of impact events from the measurement signal, wherein each of said impact events is a feature in the measurement signal caused by an electrochemical reaction during impact of one of said nanoparticles released from the capture surface on the detection electrode.
2 . The measurement system of claim 1 , wherein the controller is configured to determine the number of impact events by identifying spikes in the measurement signal.
3 . The measurement system of claim 1 , wherein the capture surface is a surface of an electrode and the controller is configured to: control a voltage source that is configured to apply a voltage between the electrode comprising the capture surface and a reference electrode, wherein the reference electrode is an internal reference electrode of the sensor or an external reference electrode of the measurement system; and initiate the dissociation process by applying a dissociation voltage between the electrode comprising the capture surface and the reference electrode via the voltage source to release electrochemically active nanoparticles adsorbed on the capture surface by one or both of electrically induced dissociation and by electrochemically induced dissociation.
4 . The measurement system of claim 3 , wherein the capture surface is a surface of a first capture electrode and the sensor further comprises a second capture electrode, wherein the controller is configured to: apply a dissociation voltage to the second capture electrode via the voltage source after applying the dissociation voltage to the first capture electrode and after determining the measurement signal.
5 . The measurement system of claim 1 , wherein the electrochemically active nanoparticles are metal nanoparticles and wherein the controller is configured to determine a size of one of the metal nanoparticles by determining one or both of an amplitude and a time-integrated current associated with an impact event of said impact events.

Description

FIELD OF THE INVENTION The present invention is in the field of chemical analysis and medical diagnostics. In particular, the invention relates to a sensor for sensing molecules by electrochemical detection of nanoparticles. BACKGROUND A large number of applications in fields ranging from chemical analysis over environmental testing to medical diagnostics rely on the detection and quantification of chemical substances. For these purposes, different types of sensors are used, which typically involve a transducing mechanism for converting a concentration of a target substance into a readily measurable quantity. A well-known example for this is the labeling of substances such as proteins with fluorescent markers, which allows for determining a number or concentration of such molecules by optical means. Similar techniques have been implemented using magnetic or electrochemically active labels and substances, for the latter see e.g. D. Grieshaber et al., Sensor 8(3), 1400 (2008) and J. Ronkainen et al., Chem. Soc. Rev. 39(5), 1747 (2010) Another commonly used type of sensor are immunoassays such as western blots or enzyme-linked immunosorbent assays (ELISAs). In an ELISA, capture antibodies configured to selectively bind to a specific antigen are coated onto a substrate and exposed to an analyte solution such that target molecules in the analyte solution comprising the respective antigen may be captured by the antibodies. Subsequently, a second type of antibodies is provided, each of which is linked to an enzyme and also configured to bind to the target molecules. Thereby, the enzymes may be immobilized on the substrate in the form of sandwich structures containing a target molecule bound between two antibodies. Finally, the chemical substrate of the enzyme is added, triggering a chemical reaction whose product may for example be detected by optical or electrochemical means, see e.g. G. Lai et al., Anal. Chem. 83, 2726 (2011). WO 2009/068862 A1 discloses a method for determining the presence or amount of a metal-labelled analyte in a sample. The method comprises adding a release agent to the metal labelled analyte to release the metal label from the analyte, the release agent forming a charged stable species with the metal label, applying a potential to bring the charged stable species to an electrode, dissolving the charged stable species under a positive potential to form metal ions, and carrying out a quantitative determination procedure such as anodic stripping voltammetry to determine the presence or amount of the metal-labelled analyte. WO 2015/042200 A1 describes a device for sequencing protein samples comprising a channel with a plurality of nanogap electrodes and a computer processor that is programmed to measure nanocurrents between pairs of nanogap electrodes to identify monomers in a biomolecule. The aforementioned techniques, however, often require complex procedures and laboratory equipment, e.g. for the fluorescent labeling of molecules or to ensure well-controlled and reproducible reaction conditions for the enzyme reaction in ELISAs. The reliability of ELISAs may furthermore be limited by non-specific adsorption of the enzyme-linked antibodies. These issues may prevent the use of the aforementioned techniques for applications requiring a fast and low-cost detection or quantification of target molecules with high sensitivity. SUMMARY OF THE INVENTION The object of the invention is thus to enable a simple and cost-efficient, yet reliable and precise sensing of target molecules in an analyte solution. This object is met by a method for sensing target molecules in an analyte solution, a sensor for sensing target molecules in an analyte solution, and a measurement system for sensing target molecules in an analyte solution. Embodiments of the present invention are detailed in the dependent claims. The method for sensing target molecules in an analyte solution according to the invention comprises (1) providing a capture surface. A plurality of capture molecules are arranged on the capture surface, wherein each of the capture molecules is configured to bind to at least one of said target molecules. The method further comprises (2) exposing the capture surface to the analyte solution to allow target molecules to bind to the capture molecules arranged on the capture surface. The method also comprises (3) exposing the capture surface to a solution containing detection molecules. Each of the detection molecules contains an electrochemically active nanoparticle. Furthermore, each of the detection molecules is configured to bind to one of said target molecules bound to a capture molecule. This hence allows said electrochemically active nanoparticles to bind to the capture surface through formation of a bond between the respective detection molecule comprising said nanoparticle and one of said target molecules bound to one of said capture molecules arranged on the capture surface. The method also comprises (