In this chapter, as a general introduction, we summarize our personal point of view on immobilization technique in order to prepare optimal and cost-effective biocatalysts. Special attention is paid to the improvement of enzyme properties via immobilization techniques. From the stabilization by multipoint covalent attachment to the generation of hydrophilic environments via post-immobilization techniques are here discussed. Immobilization techniques, a necessary tool to reuse enzyme, have to be simple and, if possible, may become a very powerful tool to greatly improve properties of every kind of enzymes: monomeric, multimeric, stable, labile, poorly selective, etc.
