TOXICITY SCREENING OF BIODEGRADABLE POLYMERS .2. EVALUATION OF CELL-CULTURE TEST WITH MEDIUM EXTRACT

Cell culture testing with material extracts was applied to toxicity sc reening of some commercial degradable plastics: a plasticized cellulos e acetate, an aliphatic polyester (Bionolle), polyhydroxybutyrate-co-h ydroxyvalerate (Biopol), and polycaprolactone (TONE polymer). Cell cul ture medium with serum was used as extraction medium. Methods for the determination of morphology and viability of cells cultured in the ext ract were investigated. Phase-contrast light microscopy of cells, enha nced by neutral red staining, provides high-contrast images for qualit ative evaluation of cell morphology and lysis. Compared to the determi nation of protein using the Bradford method and of neutral red uptake, the determination of dehydrogenase activity using ,5-dimethylthiazol- 2-yl]-2,5-diephenyl-tetrazolium bromide (MTT) is more sensitive and ac curate. The relative MTT activity of cells cultured in fresh extracts indicate that TONE polymer (all shapes) and Bionolle (test bars and fi lms) are comparable to materials currently used in the food industry ( polyethylene terephthalate, atactic and isotactic polystyrene) with no toxic effects on cells.