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Wheat germ agglutinin (WGA), PEI-coated SPA beads, for proximity-based radiometric scintillation assays. The treatment of PVT-WGA SPA beads with positively charged polyethyleneimine (PEI) blocks potential non-specific binding sites on the SPA bead surface.

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Part Number List Price Your Price Quantity
SPQ0031 15400.00 USD
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SPA Scintillation beads are microspheres containing scintillant which emit light in the blue region of the visible spectrum. As a result, these beads are ideally suited to use with photomultiplier tube (PMT) counters such as the MicroBeta2 or TopCount.

Two types of core SPA Scintillation bead are available - yttrium silicate (YSi) and Polyvinyltoluene (PVT). PVT beads are plastic, larger in size, and stay in suspension longer than the crystalline YSi beads.

Scintillation proximity assay (SPA) is a homogeneous and versatile technology for the rapid and sensitive assay of a wide range of biological processes, including applications using enzyme and receptor targets, radioimmunoassays, and molecular interactions. When 3H, 14C, 33P, and 125I radioisotopes decay, they release β-particles (or Auger electrons, in the case of 125I). The distance these particles travel through an aqueous solution is dependent on the energy of the particle. If a radioactive molecule is held in close enough proximity to a SPA Scintillation Bead or a SPA Imaging Bead, the decay particles stimulate the scintillant within the bead to emit light, which is then detected in a PMT-based scintillation counter or on a CCD-based imager, respectively. However, if the radioactive molecule does not associate with the SPA bead, the decay particles will not have sufficient energy to reach the bead and no light will be emitted. This discrimination of binding by proximity means that no physical separation of bound and free radiochemical is required.


Automation Compatible Yes
Bead Type or Core Bead Type PVT
Coating Treatment WGA
Detection Method Radiometric
Product Brand Name SPA Scintillation Beads
Quantity in a Package Amount 25.0 Units
Shipping Condition Ambient
Unit Size 500 mg

Resources, Events & More

Resource Type File Name File Format
Application Note Assay Development Guide to Protein:Protein Studies PDF  951 KB
Application Note The Application of SPA Technology to Study Protein: DNA Interactions PDF  997 KB
Application Note The Application of SPA to SH2 and SH3 Domain Binding to Specific Peptide Sequences PDF  1 MB