Complementing the classical detection modes, the advanced Time-Resolved Fluorescence (TRF) and proximity detection modes like TR-FRET and Alpha Technology widen up the ways to detect biomolecular interactions and functions.
Time-Resolved Fluorescence (TRF)
The EnSpire multimode plate reader is capable to measure Time Resoved Fluoresecence (TRF). The Delfia® (TRF detection) technology takes advantage of the chemical properties of lanthanides. These include long decay time, large Stokes shifts, sharp emission peaks and high fluorescence intensities, which result in low background and high sensitivity. Different lanthanides can be used simultaneously for multiplexed TRF assays. Suitable lanthanides for use as chelate labels are europium, samarium, terbium and dysprosium.
Homogeneous proximity assays (TR-FRET and Alpha Technology)
Proximity-based and homogeneous-assay technologies such as TR-FRET and Alpha Technology, rely on energy transfer between donor and acceptor moieties when those get in close proximity. These are homogenous assays that do not require washing steps allowing to save time by shorter procedures with fewer steps, for faster data generation while retaining highest sensitivity.
The TR-FRET detection (e.g. Lance®or HTRF, homogeneous TRF) technology takes advantage of the long decay time, large Stokes shifts, sharp emission peaks and high fluorescence intensities of the lanthanides which result in low background and high sensitivity. Similarly, the Alpha Technology, presents the advantage of low backgrounds, very high sensitivity and high signal-to-background ratio. Measuring in a time resolved mode at millisecond-scale, large shifts where the emission wavelength is lower than the excitation wavelength, and sharp emission peaks, result in very low background while signal amplification through a cascade reaction enables very high sensitivity.