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DELFIA Receptor-Ligand Binding Assays


DELFIA® assays provide an excellent non-radioactive alternative to radioactive ligand-receptor binding assays. In the DELFIA assay, a Europium-labeled ligand is used (instead of radioactively-labeled ligand). The assay can be performed on membrane preparations or whole cells. View our information on labeling your own ligand. We also provide custom labeling services. DELFIA ligand-receptor binding assays can be performed on adherent cells, suspension cells, cell membranes, and prepared tissue membranes.


What do I need to run this assay?

  • Appropriate plates
    • For live adherent cell assays, you can use standard tissue culture-treated plates indicated for fluorescence, or you can treat cells as if they are suspension in AcroWell™ plates. For TC-treated plates, basically any color is okay, though common colors are white and clear. We usually recommend opaque white CulturPlates™.
    • For membrane-based and suspension cell assays, we recommend AcroWell™ filter plates and our DELFIA L*R Binding and DELFIA L*R Wash buffers.
  • Appropriate wash and binding buffers (we recommend our DELFIA L*R Wash and L*R Binding buffers for cell membrane-based filtration assays; you should not use phosphate-based buffers when the labeled reagent is in the well - see FAQs below for other buffer recommendations)
  • Cell membrane, cell line, or tissue preparation to be studied; PerkinElmer offers receptor-transfected cell lines and cell membrane preparations
  • Eu-labeled ligand - view information on labeling your own ligand; we can custom-label your ligand as well
  • Unlabeled ligand, agonists, and antagonists as appropriate
  • DELFIA Enhancement solution
  • TopSeal™-A adhesive plate seal (do not use adhesive seals once Enhancement solution has been added to plate)
  • A TRF-capable plate reader
  • Optional: Plate shaker (we recommend our DELFIA Plateshake)
  • Vacuum manifold (for filtration assays)
  • Optional: Plate washer (for TC-treated plate assays)

96-well Acrowell plates for filtration assays:

Plate supplierCatalog number

PerkinElmer carries cell membrane preparations and cell lines overexpressing GPCRs and other receptors.


Products and catalog numbers

View a listing of DELFIA products and catalog numbers.





View a brief listing of DELFIA ligand-binding citations.


Tips and FAQs

Q: I'm using suspension cells. Can I just use a solid plate and centrifuge when I need to wash?
A: We do not recommend this. Loss of cells can lead to signal variation. We recommend you use an AcroWell™ Filtration plate. When using whole cells, Millipore MultiScreen™ FL plates can also work.

Q. I'm performing a ligand binding assay on whole, unfixed adherent cells. What wash buffer do you recommend?

A. The L*R wash concentrate is not recommended for use with whole, unfixed cells because there is no physiological concentration of sodium chloride. For a ligand binding assay using adherent, unfixed cells, we recommend using 10-15 mM Tris-HCl, 0.9% NaCl, pH 7.8 as a wash buffer. No detergent should be present in this wash buffer. You can prepare a 5X concentrate if desired. This wash solution shouldn’t be stored for more than a few days because there is no bacteriostatic agent. If a concentrate is prepared and filtered through 0.45 µm or 0.22 µm membrane, then it should be stable at +4°C at least for a few weeks.

Q. I'm performing a ligand binding assay on whole, unfixed adherent cells. What binding buffer do you recommend?

A. We suggest DELFIA Assay Buffer without detergents, 5x concentrate (Cat. No. CR85-100). This assay buffer is Tris-HCl buffered (pH 7.8) salt solution with DTPA, BSA and bovine gamma globulin. CR85-100 has no divalent cation (e.g. Mg2+) but is otherwise suitable for receptor binding assays with whole cells. CR85-100 does contain a physiological concentration of NaCl.


Custom labeling and assay development services

PerkinElmer offers custom labeling services as well as custom assay development. If you are interested in having your biomolecule custom-labeled, or in custom assay development, please contact our custom teams:

ON>POINT® Custom Labeling and Conjugation Services
ON>POINT® Custom Assay Development Services