Figure describes the protocoladapted from Shi et al used to immobilize transaminases onto PAN membranes. The PAN surface was partially hydrolyzed by dipping a 5 cm 2 disc of the PAN membrane in 50 mL of a 1.5 M NaOH solution for 2 hours at 50 °C under gentle stirring (as recommended by Pérez-Álvarez et al. ). The resulting hydrolyzed PAN membrane (HPAN) was then washed with 100 mL distilled water for 1 hour, and this washing step was repeated 3 times, before being dipped into 50 mL of a 1 wt. % (unless stated otherwise) aqueous solution of branched polyethyleneimine (PEI) for 18 hours at 37 °C under gentle stirring. The resulting membrane was washed again 4 times, stored in distilled water and is denoted HPAN_PEI.