TR-FRET Cell-based assay kits

A solution for everyone: TR-FRET Assay

Cost-efficient generation of reproducible and consistent data

Our THUNDER TR-FRET combines exceptional FRET chemistry with superior antibodies and optimised buffers, enabling lot-to-lot consistency, and flexibility in your assays. We offer technical support by the same scientists that developed the assays, and by our plate readers expertise.

Moreover, we offer a flexible and affordable solution to make sure that a broader number of labs can reach the technology and its benefits. 


Cell-based Assay kits 

We offer different kits for your cell-based assays, which target more than 100 molecules. Discover below the most commonly used, divided into phospho-proteins, human cytokines and GPCRs.


  • Extreme Phospho-ERK1/2
  • Phospho-AKTpan (S473)
  • Phospho-STAT3
  • Phospho-STAT5
  • Phospho-STAT6
  • Total STAT6
  • Phospho-SLP-76
  • Phospho-EGFR
  • Phospho-SMAD2
  • Phospho-cMet


  • cAMP

Human Cytokines:

  • IFN-gamma
  • IL-1 beta
  • IL-2
  • IL-6
  • IL-8
  • IL-11
  • IL-17A
  • TNF-alpha
  • IL-12/IL-23 p40
  • CCL2/MCP-1

What is TR-FRET?

Förster resonance energy transfer (FRET) describes a physical phenomenon of non-radiative energy transfer based on the dipole-dipole coupling that can occur from an excited state fluorophore (the donor) to a ground state fluorophore (the acceptor). FRET is detected by the appearance of sensitized fluorescence in the acceptor and by a decrease (quenching) of donor fluorescence.

FRET only occurs when the donor fluorescence emission spectrum overlaps with the acceptor excitation spectrum, when donor-acceptor relative dipole orientations are approximately parallel, and when the donor and acceptor are within close proximity (typically 1-10 nm)

Time-resolved FRET (or TR-FRET) is a well-established technology widely used in drug discovery and clinical diagnostics, and increasingly used in academic laboratories.


  • Highly versatile assay technology
  • Enables the study a wide range of biological interactions ranging from low to high affinity
  • For small and large molecules

Our THUNDER Solution

In contrast to standard FRET assays, THUNDER™ TR-FRET assays use a long-lifetime Europium chelate as the donor fluorophore. The specific FRET signal can thus be measured in a time-resolved manner, after a suitable time delay (typically 50 to 100 µs).

low background noise in your TR-FRET assays with THUNDER  kits

This virtually eliminates all fluorescent background caused by the sample and plastic microplate, and by direct excitation of the acceptor.

As a result, the THUNDER TR-FRET assays exhibitvery low background and high S/B ratios.

The THUNDERTM TR-FRET assay platform is based on the use of a carefully selected pair of donor-acceptor fluorophores showing exceptional spectral compatibility and TR-FRET signal.

  • Europium chelate (Eu) as the donor fluorophore
  • A small, unique far-red fluorophore (FR) as the acceptor.

In a sandwich immunoassay application, one antibody is labeled with the Eu chelate and the second antibody is labeled with the FR fluorophore.

The specific binding of the two labeled antibodies to distinct epitopes on the target protein takes place in solution and brings the two fluorophores into close proximity.

TR-FRET technology THUNDER for your cell based assays

Cell-based assays: Benefits of THUNDER TR-FRET

The main benefits of using our THUNDER technology for cell-based assays compared to Western Blots, ELISA and bead-based approaches are listed below: 

  • Flexibility in your assays: Our high quality TR-FRET assay kits work with adherent, suspension and transfected cells. Besides, the flexibility that offers in cell types, it also enables to:
    • Run assays in both 96 (hald-are) and 384 well plates
    • Kit assays: 100, 500, 2500, 5000, and 10000 points
    • Compatibility with most multi-mode microplate readers typically found in research labs.
  • Save time and perform simpler protocols: Easy-to-use, fast and homogeneous (no-wash) assays.
  • Low assay background: superior S/B ratios and high sensitivity.
  • Lot-to-lot consistency: High robustness and reproducibility with very long signal stability.
  • High tolerance to most experimental conditions.
  • Cost-effectiveness.

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