Calorimetric evaluation of interaction and absorption of polychlorinated biphenyls by biomembrane models.

Polychlorinated biphenyls (PCBs) are organic pollutants with lipophilic properties, due to their persistence, they are present in environment at potentially dangerous concentrations for humans health. In this work we investigated the interaction and absorption of 2,4,4'-trichlorobiphenyl (PCB 28), 2,3,3',4,4'-pentachlorobiphenyl (PCB 105) and 2,3,3',4,4',5,5'-eptachlorobiphenyl (PCB 189) with dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV), chosen as biomembrane models, by differential scanning calorimetry technique (DSC). The obtained results indicate that the tested compounds affected the thermotropic behaviour of MLV to different degree, modifying the phase transition peak and shifting it towards lower temperature. The effect of an aqueous or lipophilic medium on the absorption process of these compounds by the biomembrane models was also investigated revealing that the process is hindered by the aqueous medium but favoured by the lipophilic medium.