Application of polymer-modified silica nanoparticles in enzyme immobilization

In this study immobilization of acetylcholineesterase(E.C. 3.1.1.7) via covalent binding to modified silica nanoparticles was carried out by using polyethyleneimine (PEI) and 3-aminopropyltriethoxysilane (APTES). The effect of various parameters such as pH, temperature and storage stability on the free and immobilized enyzmes were examined. Optimum pH for free enyzme, APTES-modified and PEI-modified silica nanoparticles were found to be 7, 7 and 8 respectively. Optimum temperature for free enyzme, APTES-modified and PEI-modified silica nanoparticles were determined to be 30 oC, 30 oC ve 35 oC respectively. For free enzyme maximum reaction rate (Vmax) and Michaelis?Menten constant (Km) values were found 6,35x10-3 M and 5,00x10-4 M.min-1 respectively, and for immobilized enzyme to APTES-modified and PEI modified silica nanoparticles were found in the range of 1,19x10-2 M, 2,1x10-2 M and 3,09x10-3 M.min-1, 1,42x10-3 M.min-1, respectively.Reuse number and storage stability of acetylcholineesterase were increased with immobilization.