Immobilization of Peroxidase on SiO2 Surfaces with the Help of a Dendronized Polymer and the Avidin-Biotin System

Horseradish peroxidase (HRP) is immobilized in three easy steps on SiO2 surfaces with the help of a polycationic second generation dendronized polymer (denpol) and the biotin-avidin system. This stepwise immobilization process is monitored and quantitatively analyzed with the transmission interferometric adsorption sensor. Partially biotinylated denpol is first adsorbed onto SiO2, followed by addition of avidin and then of biotinylated HRP. Denpols in their molecular structure combine properties of polymers as well as dendrimers which are found to be of clear advantage for this type of non-covalent enzyme immobilization. With respect to the reproducibility of the adsorption process and with respect to the stability of the adsorbed polymer layer, the denpol is superior to a-poly-D-lysine which is used as a reference polymer. Furthermore, HRP immobilized with the denpol on commercial glass slides remains considerably more active upon storage as compared to HRP immobilized with the help of a-poly-D-lysine with a similar number of repeating units. The ease of the denpol-mediated HRP immobilization and the high stability of the immobilized enzyme are promising for bioanalytical applications.