Scintillation proximity assay using polymeric membranes

Liquid scintillation counting (LSC) is typically used to quantify electron emitting isotopes. In LSC, radioactive samples are dissolved in an organic fluor solution (scintillation cocktail) to ensure that the label is close enough to the fluor molecules to be detected. Although efficient, scintillation cocktail is neither specific or selective for samples labeled with the same radioisotope. Scintillation cocktail is flammable posing significant health risks to the user and is expensive to purchase and discard. Scintillation Proximity Assay (SPA) is a radioanalytical technique where only those radiochemical entities (RCE's) bound to fluor containing matrices are detected. Only bound RCE's are in close enough proximity the entrapped fluor molecules to induce scintillations. Unbound radioligands are too far removed from the fluor molecules to be detected. The research in this dissertation focused on the development and evaluation of fluor-containing membranes (scintillation proximity membranes, SP membranes) to be used for specific radioanalytical techniques without using scintillation cocktail. Polysulfone and PVC SP membranes prepared in our laboratory were investigated for radioimmunossay (RIA) where only bound radioligand is detected, thereby eliminating the separation step impeding the automation of RIA. These SP membranes performed RIA where the results were nearly identical to commercial SP microbeads. SP membranes functionalized with quaternary ammonium hydroxide moieties were able to trap and quantify 14CO2 without using liquid scintillation cocktail. RCE's bound in the pore structure of SP membranes are intimate with the entrapped fluor providing the geometry needed for high detection efficiencies. Absorbent SP membranes were used in radiation surveys and were shown to be as effective as conventional survey techniques using filter paper and scintillation cocktail