Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals
Patent
1996-07-17
1999-01-05
Chin, Christopher L.
Chemistry: analytical and immunological testing
Involving an insoluble carrier for immobilizing immunochemicals
385 12, 385129, 385130, 422 55, 422 57, 422 58, 422 8205, 422 8208, 422 8209, 422 8211, 4352871, 4352872, 4352879, 4352887, 435808, 436164, 436165, 436172, 436524, 436527, 436528, 436531, 436805, G01N 33543, G01N 33552
Patent
active
058562036
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of conducting sandwich assays of chemical, biochemical or biological entities and to devices for use in such a method.
There is a now a great interest in the development of assay devices and techniques for the detection and measurement of the presence of an analyte in a sample, and the various methods and devices available have been extensively reviewed, for example in Biosensors: Fundamentals and Applications, edited by A. P. F. Turner, I. Karube, G. S. Wilson, Oxford Scientific Publications, 1987. Standard assay techniques, however, are highly sensitive to a wide variety of conditions and interfering factors-which may affect the level of the signal observed e.g.temperature, reagent stability, incubation and development time. Accordingly, the analytical performance of standard assay techniques is often limited by the method of calibration of the immunosensor used, which usually involves carrying out an assay on a standard sample containing a known amount of analyte. In respect of assays which involve an antibody, the immunological binding reactions which occur are frequently irreversible. Thus any calibration steps need to be carried out using a separate device or devices (preferably from the same manufacturing batch) which inevitably introduces errors.
The need for a separate calibration step involving the use of additional sensing devices can be avoided by using in the assay a device which is provided with separate zones whereby the calibration step is effected within the assay procedure. Such methods applicable to both sandwich assays and competition assays are described in WO92/09892.
Standard sandwich assay techniques are particularly liable to exhibit the high dose `hook` effect (a paradoxical reversal of the standard curve at high doses of analyte), a typical standard curve for a conventional immunoassay being illustrated in FIG. 1. This effect can be eliminated by using sequential rather than simultaneous application of the different specific binding partners for the analyte under assay. Alternatively, elimination of the high dose `hook` effect necessitates assay of a sample at at least two different dilutions. The most usual way, however, of performing a one-step sandwich assay is to employ a large excess of the labelled specific binding partner to alleviate the high dose `hook` effect.
An alternative to using excess labelled specific binding partner is to reference the sandwich assay by dosing a known amount of the analyte under assay into the assay device. In the absence of the analyte of interest in the sample, a fixed signal will be obtained, but when analyte is present the dose-response curve of the reference assay will be offset compared with that of the test assay, the relative magnitude of the offset decreasing with increasing analyte concentration. Eventually, however, at high analyte concentration the offset becomes zero as the immobilised specific binding partner is saturated with analyte. This is illustrated for an immunoassay in FIG. 2 and clearly, therefore, such referencing techniques will not be satisfactory at all concentrations of analyte present in the sample but especially at high analyte concentration and do not alleviate the high-dose hook effect.
In the sandwich assay techniques described in WO92/09892, one method of referencing employs a device having a reference zone containing an immobilised specific antibody to the antigen under assay, the reference zone also containing a pre-complexed mixture of a labelled second specific antibody to the antigen under assay and the antigen under assay. Although such a complex is likely to be more stable than the separate components it is, unfortunately, unable to mimic the performance of the second specific binding partner in the measurement zone of the device. There can be also be a further disadvantage with this type of referencing in that should the second specific antibody have degraded during manufacture or storage of the device, no information can be gained about its reactivity by interro
REFERENCES:
patent: 4978503 (1990-12-01), Shanks et al.
patent: 5141868 (1992-08-01), Shanks et al.
patent: 5512492 (1996-04-01), Herron et al.
patent: 5525466 (1996-06-01), Slovacek et al.
Fletcher Janys
Robinson Grenville Arthur
Applied Research Systems ARS Holding NV
Chin Christopher L.
LandOfFree
Sensor device for sandwich assay does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sensor device for sandwich assay, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sensor device for sandwich assay will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-861719