Abstract
We have developed a one-step, homogeneous non-competitive immunoassay
for small analytes using recombinant antibodies and morphine as the model
analyte. Small analytes e.g. abused drugs are an important and increasingly
growing area of analytes. Competitive immunoassays performed in microtiter
wells or dipsticks are relatively simple methods for detection of drugs of
abuse. However, due to the unspecific nature of competitive immunoassays,
these tests generate many false positives. Commercial immunoassay tests for
morphine and heroin crossreact with e.g. codeine which is a widely used
substance in cough medicines. Thus those tests are considered as opiate
specific and confirmation of the morphine abuse must always be confirmed by
other techniques. This is not only a technical issue but raises also ethical
concerns. In our assay format a highly specific antibody against the immune
complex (IC) formed between an anti-morphine antibody and morphine was
selected from a na¿ve scFv phage display library. The in vitro phage library
selection procedure avoids the difficulties associated with the production of
anti-IC antibodies by animal immunisation. The anti-morphine and the anti-IC
antibodies were labeled with a pair of fluorescence resonance energy transfer
(FRET) fluorophores. In the FRET assay the labelled antibodies were incubated
with saliva samples spiked with morphine, codeine, or heroin. Within two
minutes, 5 ng/ml of morphine, which is clearly under the recommended cutoff
level, was detected without cross-reactivity to codeine or heroin. This assay
principle is also widely applicable to other small analytes such as
pharmaceuticals, toxins, steroids etc.
Original language | English |
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Publication status | Published - 2006 |
MoE publication type | Not Eligible |
Event | 5th International Congress on Recombinant Antibodies - Zürich, Switzerland Duration: 27 Jun 2006 → 29 Jun 2006 |
Conference
Conference | 5th International Congress on Recombinant Antibodies |
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Country | Switzerland |
City | Zürich |
Period | 27/06/06 → 29/06/06 |