Plate reader

They are widely used in research, drug discovery,[1] bioassay validation, quality control and manufacturing processes in the pharmaceutical and biotechnological industry and academic organizations.

Higher density microplates (384- or 1536-well microplates) are typically used for screening applications, when throughput (number of samples per day processed) and assay cost per sample become critical parameters, with a typical assay volume between 5 and 50 μL per well.

Several conventional colorimetric analyses have been miniaturized to function quantitatively in a plate reader, with performance suitable for research purposes.

Examples of analyses converted to plate reader methods include several for ammonium, nitrate, nitrite,[4] urea,[5] iron(II),[6] and orthophosphate.

A typical luminescence optical system consists of a light-tight reading chamber and a PMT detector.

The ability to select multiple wavelengths, or even wavelength ranges, allows for detection of assays that contain multiple luminescent reporter enzymes, the development of new luminescence assays, as well as a means to optimize the signal to noise ratio.

It relies on the use of very specific fluorescent molecules, called lanthanides, that have the unusual property of emitting over long periods of time (measured in milliseconds) after excitation, when most standard fluorescent dyes (e.g. fluorescein) emit within a few nanoseconds of being excited.

The drawbacks are that the instrumentation and reagents are typically more expensive, and that the applications have to be compatible with the use of these very specific lanthanide dyes.

The main use of TRF is found in drug screening applications, under a form called TR-FRET (time-resolved fluorescence energy transfer).

Robustness, the ability to automate and miniaturize are features that are highly attractive in a screening laboratory.

The measured forward scattered light indicates the amount of the insoluble particles present in solution.