Plate-based binding assays

In most cases, the test compounds are dissolved in DMSO and are added from a source plate into the assay. Thus, the tolerance of the assay for DMSO should be tested, by looking at the activities at various increasing concentrations of DMSO. Generally, enzymatic or biomolecular binding assays are more tolerant of high DMSO concentrations (often up to 5% to 10% DMSO). Cell-based assays usually can tolerate up to 0.5% DMSO. 

We have developed an LC-based sensor which relies upon the displacement of a drug-dye conjugate from a CAP-imprinted polymer upon application of samples containing the original template molecule (Fig. 20.15). This is essentially a competitive binding assay in a flow injection format. The increased number of theoretical plates available during the separation serves to greatly enhance the selectivity of the assay. 

A systematic approach to profiling active metabolites using a 96-well plate format was recently described (Shu et al., 2002). The approach is based on a rapid bioassay-guided metabolite detection and characterization. Drug metabolite mixtures (generated by various methods described below) are separated and fractions collected into microtiter plates such as 96-well plates. The fractions are then subjected to one or more relevant activity (e.g., receptor ligand binding) assays. 

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