Assays
FLUORESCENCE
LIFETIME finally picking up momentum!
Fluorescence lifetime (FLT) largely failed to make a significant inroad as a screening technology when it was first introduced nearly a decade ago, despite the fact that intrinsically it has many benefits, particularly in dealing with assay interferences. Market studies undertaken in the intervening period have consistently uncovered a latent appetite within drug discovery for FLT assays. Recent publications have successfully addressed target class applicability, assay validation and assay reagent availability issues using FLT. The FLT reader situation has also changed with the launch of a new dedicated FLT plate reader from Edinburgh Instruments able to generate a large signal window with excellent precision using Almac’s FLEXYTE® assay kits. There is an undoubted sense that the momentum around FLT is picking up and the recent advances in FLT discussed in this article make FLT a more attractive assay technology option today.
F
luorescence lifetime (FLT) was first offered as a detection modality on a multi-mode plate reader by Tecan back in 2002. Not long after its introduction we discussed assay inter- ference as a limiting factor in HTS1. In this article we concluded that FLT had the potential to deliver the greatest signal robustness (ie ability to circum- vent assay interferences) of the then available assay technologies, but its HTS fitness (ie suitability of an assay technology for screening) was inadequate. At that time (Summer 2003) this inadequacy cen- tred around the paucity of publications supporting the use of FLT against a diversity of target classes; few, if any, examples of validated FLT applications citing assay development experience; and limited availability of specific probes and assay kits opti- mised around their FLT characteristics. During the
Drug Discovery World Summer 2010
interim period HTStec has undertaken two sur- veys2,3 to investigate the disconnect in FLT adop- tion. In both cases we uncovered a latent interest and an appetite within the drug discovery commu- nity to consider FLT assays.
How is FLT perceived? Survey respondents’ perception of FLT as a screen- ing technology in 2007 are presented in Figure 1. This shows that only a small minority thought FLT was an excellent research and screening analytical technique. The majority perceived FLT as a prom- ising analytical technique that needs to mature, fol- lowed by an interesting but largely unproven assay technology. This figure nicely illustrates the need for more end user references supporting the suc- cessful application of FLT.
71 By Dr John Comley
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