ULTRASENSITIVE DIAGNOSTIC DEVICE USING ELECTROCATALYTIC FLUID DISPLACEMENT (EFD) FOR VISUAL READOUT
Disclosed herein are methods and systems to detect low-concentration analytes by transducing small electrochemical currents into easily perceived, high-contrast visual changes using a new approach termed electrocatalytic fluid displacement (EFD)
1 . A detection system for detecting a target analyte in a sample, the system comprising:
a first chamber comprising a sensor electrode capable of presenting a biomolecular probe at the surface thereof, said probe capable of binding the target analyte;
a second chamber comprising a readout electrode electrically coupled to the sensor electrode;
a peroxide solution; and
a metal catalyst.
2 . The detection system of claim 1 , wherein the first chamber comprises a redox reporter comprising Ru(NH 3 ) 6 3+ and a reducing agent, wherein the reducing agent is not oxidizable or reducible by Ru(NH 3 ) 6 3+ or Ru(NH 3 ) 6 4+ .
3 . The detection system of claim 2 , wherein the reducing agent is selected from: 3-mercaptopropionoic (MPA) acid, cysteamine (Cys), mercaptoethanol (MCE), cysteine, tris(2-carboxyethyl)phosphine (TCEP), and ethanolamine.
4 . The detection system of claim 2 , wherein the reducing agent comprises a combination of agents selected from: 3-mercaptopropionoic (MPA) acid+cysteamine (Cys); mercaptoethanol (MCE)+cysteamine; cysteine+tris(2-carboxyethyl)phosphine (TCEP); ethanolamine+TCEP; cysteine+cysteamine; and ethanolamine+cysteamine.
5 . The detection system of claim 1 , wherein binding of the target analyte to the probe on the sensor electrode generates an electrical current that results in electrodeposition of the metal catalyst on the readout electrode.
6 . The detection system of claim 5 , wherein electrodeposition of the metal catalyst on the readout electrode causes decomposition of the peroxide present in the second chamber.
7 . The detection system of claim 6 , wherein decomposition of peroxide generates oxygen bubbles.
8 . The detection system of claim 7 , wherein generation of bubbles displaces a dye present in the peroxide solution.
9 . The detection system of claim 8 , wherein the second chamber comprises a colored spot beneath the readout electrode.
10 . The detection system of claim 9 , wherein displacement of a dye in the peroxide solution reveals the colored spot beneath the readout electrode.
11 . The detection system of claim 1 , wherein the sensor electrode is a nanostructured microelectrode.
12 . The detection system of claim 1 , wherein the readout electrode is a mesh or high-edge-density electrode.
13 . The detection system of claim 1 , wherein the sensor electrode is electrically coupled to the readout electrode through a platinum wire electrode.
14 . The detection system of claim 1 , wherein the peroxide solution and metal catalyst are added to the second chamber sequentially.
15 . The detection of system of claim 1 , wherein the peroxide solution and metal catalyst are added to the second chamber simultaneously.
16 . The detection system of claim 1 , wherein the metal catalyst is platinum.
17 . The detection system of claim 1 , wherein the analyte is nucleic acid.
18 . The detection system of claim 1 , wherein the probe is a peptide nucleic acid probe or a nucleic acid probe.
19 . The detection system of claim 1 , wherein the second chamber comprises a lid comprising a diffraction grating, wherein generation of bubbles causes an index mismatch at the diffraction grating, causing a structural color change.
20 . The detection system of claim 1 , wherein the second chamber comprises a lid comprising a photonic structure, wherein generation of bubbles induces the appearance or disappearance of incoherent scattering, coherent scattering or iridescence, causing a structural color change.
21 . The detection system of claim 20 , wherein the lid is made of material having an index of refraction substantially the same as peroxide.