Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to modify an electrical circuit, and then measuring a change in the electrical state of the circuit. A diagnostic element useful in such a method includes a layer of a biogenic substance, such as an antigen, coated onto a non-conductive base between a pair of electrical conductors superposed on the base. Antibodies which react with the antigen are treated so that they become bound to particles. The particles having antibody bound thereto are then added to is the antigen lay e base and allowed to react therewith. The particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which modify the circuit. The particles are then selectively coated with a conductive substance.

Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to modify an electrical circuit, and then measuring a change in the electrical state of the circuit. A diagnostic element useful in such a method includes a layer of a biogenic substance, such as an antigen, coated onto a non-conductive base between a pair of electrical conductors superposed on the base. Antibodies which react with the antigen are treated so that they become bound to fine electrically conductive, metallic particles. The electrically conductive particles having antibody bound thereto are then added to the antigen layer deposited on the base and allowed to react therewith. Electrically conductive particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which modify the circuit.

Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to complete an electrical circuit, and then measuring a change in the electrical state of this circuit. In a preferred embodiment, a layer of antigen is coated onto a non-conductive base between a pair of electrically conductive layers superposed on the base. Antibodies which react with the foregoing antigen are treated so that they become bound to fine electrically conductive, metallic particles. The electrically conductive particles having antibody bound thereto are then added to the antigen layer deposited on the base and allowed to react therewith. Electrically conductive particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which bridge the electrically conductive layers and complete the circuit.

Abstract: A competitive enzyme-linked immunoassay for a soluble analyte in which the analyte in the unknown sample and the same analyte attached to a solid phase (immunosorbent) compete for a selected quantity of a soluble first antibody to the substance; a second or bridging antibody is then linked to any first antibody linked to the immunosorbent as a result of the competitive reaction, following which a soluble enzyme/antibody immune complex is linked to bridging antibody on the immunosorbent. The enzymatic activity associated with the thusly-formed enzyme-immunosorbent complex or with the non-immunosorbent fraction of enzyme is measured to determine the presence and/or concentration of analyte in the unknown sample.