Enzyme loadings on the membranes were evaluated by mass balance. Typically, a functionalized membrane was incubated in a 5 mL (V0) TA solution of known concentration, C0 [mg.mL ]. After immobilization, the membrane was removed from the reactor and the TA concentration in the remaining solution (C1) was measured by Bradford titration (see ESI). The membrane was then washed with 5 mL (V0) of rinsing solution, and the enzyme concentration in the resulting solution was measured (C2). The same procedure was applied to the next rinsing solutions, leading to measure C3 and C4. The immobilized enzyme loading (L) was determined by Eq. 1. The immobilization yield (%) is defined as the ratio between immobilized TA (L) and the total TA mass introduced during the immobilization (5 x C0).