A plethora of different surface functionalization techniques (e.g. wet chemical modifications,, plasma or UV exposure) have been reported in the literature , showing a variety of approaches, depending on the substrate chemical nature. The implementation of such surface modifications depends on the type of enzyme immobilization (e.g. covalent grafting, electrostatic-assisted adsorption, sitespecific immobilization through coordination) that is envisaged, as well as the membrane operation which are targeted in the intensified biocatalytic process. Among the different existing strategies, silanization of inorganic membrane surface using (3-aminopropyl)triethoxylsilane (APTES) and polydopamine (PDA) coating deposition on polymeric membranes have been employed over the recent years to confer amino-groups at their surfaces, serving as anchoring points for grafting. In these cases, glutaraldehyde (GA) is most conventionally used as a coupling agent between the enzyme and the functionalized membrane. Another general trend is to try and stabilize the immobilized enzymes via electrostatic interactions; polyelectrolytes such as polyethyleneimine (PEI) are often employed with this aim.