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Abstract

The present invention relates to diagnostic assays whereby the detection means is based on electrochemical reactions. This means that the label to be detected provides an electric signal. Preferred labels are enzymes giving such a signal. Provided is a flow cell whereby a solid phase is provided in a flow stream of the sample, in close proximity to a working electrode to detect any electrical signal. In a typical embodiment, a sample is mixed with molecule having specific binding affinity for an analyte of which the presence in the sample is to be detected, whereby said specific binding molecule is provided with a label. The conjugate of labelled specific binding molecule and analyte is then immobilized on the solid phase in the vicinity of the working electrode, the flow cell is rinsed with a solution and afterwards a substrate solution for the label (an enzyme) is provided upon which an electrical signal is generated and can be detected by the working electrode. The methods and devices of the present invention are particular useful for liquids which comprise many substances that may disturb measurement in conventional assays. The design of the flow cell allows for removal of said interfering substances before measurement. In a preferred embodiment at least part of the solid phase is provided in the form of magnetic beads. In this embodiment the solid phase can be mixed with the sample thereby creating a longer reaction time, a better sensitivity and a higher speed of the assay.

First Claim