Imaging systems in assay screening

High-throughput screening laboratories continuously seek higher throughput, lower cost and compound conservation. In an attempt to approach these goals, improvements in traditional detection instruments (e.g. scintillation counters, fluorescence plate readers, luminometers) are being made. A more radical alternative is the use of image-based detection methods, which have the advantage that large numbers of wells can be quantified in a single detection procedure (favouring miniaturization) and that faint luminescence or scintillation assays can be accomplished very rapidly. However, image-based screening is a very new technology and must prove itself before being broadly accepted. In this review, the technology of a commercial instrument for image-based screening (the LEADseeker(TM) from Amersham Pharmacia Biotech, Amersham, UK) is described, and its performance summarized with scintillation, luminescence, fluorescence and absorbance signals.