Assessing performances of Iodogen-coated surfaces used for radioiodination of proteins

Performances of Iodogen-coated surfaces were assessed by measuring kinetics of iodide oxidation with a spectrophotometer. The iodide was effectively oxidized by a surface of high Iodogen concentration. The oxidation rate tended to reach a plateau at 8.45 micrograms cm-2. Increasing the total mass of coating without changing the surface concentration did not increase the rate of oxidation. At each level of concentration, the magnitude of iodide oxidized was proportional to the amount applied in a log-linear pattern providing that the quantity of Iodogen was in constant excess. Oxidation on polypropylene, borosilicate and soda-lime glasses were also investigated. Nonpolar polypropylene surfaces yielded the lowest rate of oxidation while polar soda-lime glass yielded the highest. Borosilicate surface was rated at an intermediate level, but it did not provide good matrix for coating due to its poor reproducibility. It appeared that both polypropylene and borosilicate surfaces might trap a certain fraction of the Iodogen and reduce the effective surface concentration. Findings in this study supply fundamental guidelines for surface selection and preparation.