1. Introduction
The immobilization of biomolecules on solid surfaces is an essential technique in several biotechnological applications [1]. Among different surfaces, membranes are receiving more and more attention in biotechnology. Bio-functional membranes are applied in biocatalysis [2] and [3], separations [4], and biosensors [5] and [6].
A key requirement is to immobilize proteins without losing their bioactivity. It is well known that the physical and chemical properties, activity and stability of a protein depend on both the immobilization method and the type of polymeric matrix. Then, the choice of the appropriate support, in terms of materials, reactive groups as well as the immobilization conditions is of primary importance in the production of bio-hybrid systems. An ideal support must include physical resistance, hydrophilicity, inertness toward proteins, resistance to microbial attack, and availability at low cost [7].