In the latter study, the membrane unit consisted in a 3-layers system, composed of PS electrospun nanofibers placed between a pristine commercial membrane (PES, 30 kDA or cellulose, 10 kDA) and a macroporous support layer. To make them amenable to enzyme grafting, the PS nanofibers were functionalized with tannic acid (TA) and APTES prior enzyme immobilization. This approach allowed to significantly improve the catalytic performance (i.e. constant productivity over time and controlled saccharides molecular weight in permeate) with respect to the EMR employing free enzymes (which showed rapid deactivation over time).