Second, the obtained PP_PDA membrane was modified with a bisepoxide coupling agent (glycerol diglycidyl ether; GDE) to confer an appropriate linker arm for the subsequent covalent grafting of the enzyme 56 (Figure , step 1). The PP_PDA was immersed in 50 mL of a 100 mg/mL GDE solution (in ethanol) and stirred for 18 hours (unless stated otherwise) at room temperature. The resulting PP_PDA_GDE membrane was then rinsed with 50 mL of ethanol for 1 hour first, then with 100 mL distilled water for 1 hour (repeated three times).