PHOTOSYNTHETIC MEMBRANES .28. A BIOASSAY OF THYROTROPIN BY PHOTOGRAFTED MAMMALIAN-CELLS ONTO POLYMERIC SUPPORTS

Viable and functionally responsive human thyroid follicular cells, sus pended in a commercial polyester acrylate diluted with tripropylenegly col diacrylate, photoinitiated, and photocatalyzed with a proprietary photocatalytic system based on a synergic mixture of vanadium (V) t-bu toxide and i-propoxide, have been immobilized as monolayers onto polys tyrene plates. Bioassay of thyrotrophin in immobilized cell cultures y ielded, by log-log plot of the dose-response curve, a slope (0.92 +/- 0.02) in close agreement with that (0.91) reported for cells immobiliz ed by physical adsorption. The decisive role of photocatalyst in the p hotografting procedure has also been shown experimentally. A mechanism is suggested by which cells are anchored, rapidly and with stable che mical bonds, onto one of the two acrylate functions of the monomer-pre polymer mixture, the other one being simultaneously responsible for ph otochemical grafting onto the support.