AlphaScreen (Amplified Luminescent Proximity Homogeneous Assay) is a proprietary Perkin Elmer bead-based chemistry used to study biomolecular interactions.


The interaction between molecules bound on the beads promotes an energy transfer from donor to acceptor beads, producing a luminescent signal.


Upon illumination at 680 nm, donor beads convert ambient oxygen to an excited form of O2, singlet oxygen. If an acceptor bead is within 200 nm proximity, energy is transferred from the singlet oxygen to the Acceptor bead, culminating in light production at 520 – 620 nm. In the absence of an acceptor bead, singlet oxygen falls to ground state and no signal is produced. All BMG LABTECH multi-mode plate readers can be equipped with AlphaScreen detection. AlphaLISA and AlphaPlex assays are based on the same principle and differ mainly in the emission wavelengths.


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AlphaScreen assays

Microplate reader detection of AlphaScreen assays requires a light source, preferably a laser exciting samples exactly at 680 nm, an emission filter discriminating between the different wavelengths and a detector (PMT).


Common AlphaScreen assays are ligand-receptor binding, competition or cleavage assays and detection of secondary messengers.


See some application notes examples for Alpha Technology below.



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