The mechanical and leaching stability of enzymes adsorbed on macroporous carriers is an important issue for the technical applicability of such biocatalysts. Both can considerably benefit from the deposition of silicone coating on the carrier surface. The coating of the immobilized lipase Novozyme 435 (NZ435),
as a model enzyme preparation, with different silicone loadings was studied in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by energy-dispersive X-ray spectroscopy (EDX) and BET isotherms, and offers explanations and prerequisites for its stabilizing
effects. The deposition of silicone on the poly(methyl methacrylate) (PMMA) carrier was found to form an interpenetrating network composite rather than the anticipated core-shell structure. The silicone precursors homogeneously wet the carrier surface including all inner pores and gradually fill the complete carrier. In parallel, the surface area of NZ435 decreases from an initial value of 89 m2g1to 0.2 m2g1after silicone loading. A visible layer of silicone on the outer surface of the carrier was only observed at a silicone concentration of 54% w/w and more. Maximum leaching stability corresponds to the formation of this layer. The mechanical stability increases with the amount of deposited silicone. It can be expected that stabilization against leaching and/or mechanical stress by
formation of silicone composites can easily be transferred to a whole range of alternative biocatalytic systems. This should considerably advance their general technical applicability and overall implementation of biocatalysts in chemical synthesis.