Si nanocolumns as novel nanostructured supports for enzyme immobilization

Silicon nanocolumns have been used as novel supports for the high-density immobilization of enzymes. Silicon nanocolumns with diameters of ca. 50-100 nm and a height of 1 micron were constructed using glancing angle deposition. The surfaces were successively treated with 3-aminopropyltriethoxysilane (APTES) and then with an amine reactive polymer, poly(ethylene-alt-maleic anhydride), to attach soybean peroxidase (SBP) to the support. Optimal coverage of APTES, polymer, and SBP was obtained for incorporation of enzyme onto the sidewalls of the nanocolumns. SBP immobilized on the silicon nanocolumns demonstrated an enhancement in biocatalytic activity of 160% over that of the enzyme immobilized on flat silicon wafers with the same projected area. The enzymatic activity decreased with progressive washes for both supports. This decrease in the activity of enzyme was found to be primarily due to the intrinsic deactivation of immobilized enzyme on the silicon surface. Designing nanocolumns with optimal dimensions, spacing, and surface chemistry may lead to the development of high-density arrays of proteins for applications in biotechnology.