Scintillation proximity assay (SPA) is a homogeneous, versatile assay technology for the rapid and sensitive analysis of a wide range of biological processes. The assay format requires no separation step and is amenable to automation, making it particularly suited to high-throughput screening applications. SPA is a well-established technology, supported by more than 10 years of application data generated both independently and by scientists at GE Healthcare. SPA is cited in over 500 literature references.
SPA is widely recognized as the "gold standard" for radiometric high-throughput screening. Assays using either SPA Scintillation Beads or SPA Imaging Beads can be read on scintillation counters and CCD imagers respectively.
Applications include receptor-ligand binding assays, enzyme assays, radioimmunoassays, and molecular interaction assays.
Key benefits
- Homogeneous: No separation or washing steps required - simply mix and measure
- Versatile: A range of bead coatings for a wide variety of targets
- Reduced assay costs: Eliminates requirement for filters and scintillation cocktails
- Reduced disposal costs: No radioactive liquid waste from filtration steps
- Improved safety: Streamlined assays mean less handling
- Precise: Absence of separation steps reduces potential errors
- Convenient: Beads are pre-coated for optimization of quantity per assay
- Automatable: compatible with 96-, 384-, and 1536-well formats
- Compatible with scintillation counters or CCD imagers
Product range
- SPA Imaging Beads - ideally suited for CCD imagers
- SPA Scintillation Beads - ideally suited for scintillation counters (see the SPA Guide below for recommended instrument settings)
- SPA Scintillation Kits - SPA scintillation bead-based assays for popular targets in easy-to-use kit form
Benefits of SPA assays compared to coated plates
If you currently use coated plate based methods, you may wish to consider the following advantages of switching to assays based on the use of SPA beads:
- Higher surface area of SPA beads - allows the concentration of key assay components (e.g. receptor membrane) to be adjusted, giving greater flexibility in assay design
- Greater binding capacity of SPA beads - higher signal produced allows potential reduction in the amount of radioactive label required. The amount of SPA bead can be altered to optimize the sensitivity of an assay
- SPA beads are format independent - easier to transfer assays to higher density plates
- Flexibility - choice of four different core bead types allows optimization of signal and background over a wide range of applications
- SPA beads are not dependent on one plate type or supplier