PP membranes were functionalized in three steps. First they were coated with PDA with the aim to provide reactive amine functions for further functionalization of the PP support . A 5 cm 2 disc of PP membrane was immersed into 10 mL of ethanol in order to wet its surface and pores. Simultaneously, a dopamine (i.e. 3-hydroxytyramine) hydrochloride solution was prepared in a 10 mM Tris buffer (pH 8.5) at a concentration of 2 mg/mL, and left to stir. After about 15 min, dopamine started to self-polymerize and the colorless solution turned pale brown.