Reactive Green 19 modified poly(HEMA) nanostructures for alcohol dehydrogenase immobilizationIn this presented work, poly(HEMA) nanostructures were prepared by using surfactant free emulsion polymerization technique. Magnetic character was introduced to the polymer by simple adding of Fe3O4 to the polymerization medium while polymerization taken place. These magnetic nanostructures were modified with Reactive Green 19 dye by nucleophilic substitution reaction. Synthesized dye attached poly(HEMA) nanostructures were characterized by FTIR, ESR, AFM and EDX analysis. These nanostructures were used for immobilization of alcohol dehydrogenase by the help of dye affinity interaction. Effects of medium pH and temperature, and substrate concentration on the activity of the alcohol dehydrogenase were investigated. Optimum pHs for free and immobilized alcohol dehydrogenase were found to be 8.0 (in phosphate buffer), while optimum temperature of both enzyme types was found to be 25 °C. Kinetic parameters of free and immobilized enzyme were also determined. Both Km ad Vmax values of the immobilized alcohol dehydrogenase were found to be higher than that of free enzyme. Also, thermal, operational and storage stability of immobilized enzyme were investigated and it was found that immobilized preparation showed more stability than free one. Immobilized preparation worked 10 successive reuse with a little decrease in its activity.