Radioactivity intensifying screens

Following immersion of the glass slides in a 1.0 (w/v) BSA-BSA solution to a depth of 2.1 cm for 30 min at 21°C, the slides were thoroughly rinsed in PBS by dilution/displacement. The slides were then completely immersed in PBS, where they were kept for different lengths of time, i.e., for 1, 2, 4, and 16 hrs. Thereafter, the slides were removed and air-dried and placed on X-ray film between Lanex Intensifying Screens as described above. The supernatants from these diffusion experiments were then concentrated 10 times by evaporation in order to establish their radioactive content. 

Open an X-ray film cassette in a dark room illuminated with a weak green or red light. Mount the intensifying screen, place a piece of X-ray film on it, and lay the dry gel or membrane on top. If no radioactive ink or radioactive labeled markers are used, prick a needle through gel and film to allow identification of the exact position of the gel after development. 

Laskey, R A. (1980) The use of intensifying screens or orgamc scintillators for visualizing radioactive molecules resolved by gel electrophoresis. Methods Enzymol 65,363-371... 

Intensifying screens are used for P whereas fluorography can be used for C, H. Some highly radioactive samples may require very short exposure times or slower films without screens. 

Laskey, R. (1980). The Use of Intensifying Screens or Organic Scintillators for Visualizing Radioactive Molecules Resolved by Gel Electrophoresis, Methods Enzymol. 65 363-371. 

When dry, mark the plates with S-labeled radioactive or fluorescent ink and expose the plates to X-ray film or to a phosphorimager plate. If autoradiography is to be used, presensitization of the X-ray film with a flash of orange light to an optical density of 0.2 and exposure with an intensifier screen at - 70°C will greatly increase the sensitivity of detection of P-labeled peptides. 

Mark the plate around the edges with S-labeled radioactive ink and expose to presensitized X-ray film at -70°C with an intensifier screen or to a phosphorimager plate. 

If an intensifier, such as the 85 mm presented here, is now replacing the screen, a relative gain of the order of x50 is obtained which results in a conversion factor of 1 to 7.5 (1 incident X photon --> 7.5 electrons). This conversion efficiency not only resolves the quantum sink problem but also increases the light level significantly to compensate for the low gamma fluxes obtained from radioactive sources. 

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