Enzyme-linked immunosorbent sensor ("elis-s")

A method of analyzing a sample using an electrochemical based sensor system, the method comprising:

• a) applying a sample (600) possibly containing a target biomarker (601) to a surface of an electrochemical based sensor (050), wherein the electrochemical based sensor comprises:
• i. an electrode analysis device (099);
• ii. a working electrode (100) comprising a surface (101), wherein capture molecules (102) are adsorbed onto the surface (101) of the working electrode (100) to generate an occupied capture surface and a plurality of blocking molecules (105) are adsorbed onto a remaining unoccupied capture surface;
• iii. a counter electrode (200);
• iv. a pseudo-reference electrode (300), wherein the working electrode (100), the counter electrode (200), the pseudo-reference electrode (300), and the electrode analysis device (099) are electrically connected;
• b) applying a detection molecule (700) and a redox-capable enzyme (753) to the surface of the sensor (050), wherein the detection molecule (700) is designed to bind to the target biomarker (601) to form a detection molecule-target biomarker complex (702);
• c) incubating the sample (600), the detection molecule (700) and the redox-capable enzyme (753) on the sensor (050) for a period of time, such that the target biomarker (601) possibly present in the sample (600) may bind the detection molecule (700) to form the detection molecule-target biomarker complex (702);
• wherein the capture molecule (102) and the detection molecule-target biomarker complex (702) form a sandwich complex (703) upon binding of the capture molecule (102) to the detection molecule-target biomarker complex (702), said sandwich complex (703) comprising the capture molecule (102) bound to the detection molecule-target biomarker complex (702);
• and
• d) applying a substrate solution comprising a chromogenic substrate the surface of the sensor (050);
• wherein the redox-capable enzyme catalyzes a redox reaction in which the chromogenic substrate donates electrons to catalyze hydrogen peroxide into water;
• wherein the chromogenic substrate is thus oxidized to form an oxidized form of the chromogenic substrate;
• wherein the oxidized form of the chromogenic substrate comprises an electrically-detectable compound, wherein the electrically-detectable compound is reduced to an unoxidized form of the chromogenic substrate via a working electrode reducing potential applied to the working electrode (100), said working electrode reducing potential transfers electrons from the working electrode (100) to the electrically-detectable compound, thus reducing the electrically-detectable compound to the unoxidized form of the chromogenic substrate, wherein a possible working electrode-counter electrode current change is thus generated, wherein said working electrode-counter electrode current change is measured as a function of time by a potentiostat (099) using chronoamperometry, and wherein said working electrode-counter electrode current change may be used to perform at least one of detection of the target biomarker (601) or quantification of the target biomarker (601).