Immunoassay technology has advanced considerably since the era when all assays were performed in glass test tubes with dangerous radioactive tracers over a period of several days. The microtiter plate is ubiquitous, and its standard 96-well version is now routinely subdivided into over 1,500 assays that can fit in the palm of your hand.
Enzymatic and fluorescent tracers make it possible to perform assay work quickly and in a relatively uncontrolled environment. The solid-phase format of immunoassays can often be replaced with no-wash, homogenous assays utilizing time-resolved fluorescence (TRF), fluorescence resonance energy transfer (FRET, TR-FRET), and fluorescence polarization (FP)-based methods.
A recent assay innovation is the multiplexed assay, pioneered by Luminex (www.luminexcorp. com) as well as other vendors. Multiplexed assays allow two, three, four, or even a dozen assays to be run simultaneously on one single sample of as little as 100 microliters.
Even so, nearly all of the commercial multiplexed assays are two-site, immunometric sandwich assays that only work with large analytes. (For oligopeptides, about 2830 amino acid residues is a critical minimum size.) So while this has worked well for large substances like interleukins, small molecule analytes like steroids, prostaglandins, and leukotrienes have not been developed to the same extent.
This article briefly describes Cayman Chemical's (www.caymanchemical.com) development of assays for prostaglandins (PGE2, PGD2), thromboxanes, (TXB2), and leukotrienes (CTC4 and LTB4) utilizing Luminex, Meso Scale Discovery (www.meso-scale.com), and fluorescence polarization