Monosize poly(2-hydroxyethyl methacrylate-co-N-methacryloly-L-histidinemethylester) [mon-poly (HEMA-MAH)] nanospheres were prepared via surfactant-free emulsion polymerization method. L-Histidine groups of the mon-poly(HEMA-MAH) nanospheres were chelated with Fe 3þ ions. Mon-poly(HEMA-MAH) nanospheres were characterized by Fourier transform infrared spectroscopy, proton NMR, and scanning electron microscopy. Particle size of the mon-poly(HEMA-MAH) nanospheres was measured by Zeta Sizer. Elemental analysis of MAH for nitrogen was estimated as 0.94 mmol/g polymer. The catalase immobilized onto the mon-poly(HEMA-MAH)-Fe 3þ nanospheres resulted in increasing the enzyme stability with time. Optimum operational temperature for both immobilized preparations was the same, and the temperature profiles of the immobilized preparations were significantly broader. It was observed that enzyme could be repeatedly adsorbed and desorbed on the monpoly(HEMA-MAH)-Fe 3þ nanospheres without loss of adsorption capacity or enzymic activity.

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Novel magnetic nanoparticles with an average size of 350-400 nm with N-methacryloyl-(L)-phenylalanine (MAPA) as a hydrophobic monomer were prepared by the surfactant-free emulsion polymerization of 2-hydroxyethyl methacrylate, MAPA, and magnetite in an aqueous dispersion medium. MAPA was synthesized from methacryloyl chloride and L-phenylalanine methyl ester. The specific surface area of the nonporous magnetic nanoparticles was found to be 580 m 2 /g. Magnetic poly[2-hydroxyethyl methacrylate-N-methacryloyl-(L)-phenylalanine] nanoparticles were characterized by Fourier transform infrared spectroscopy, electron spin resonance, atomic force microscopy, and transmission electron microscopy. Elemental analysis of MAPA for nitrogen was estimated as 4.3 Â 10 À3 mmol/g of nanoparticles. Then, magnetic nano-poly[2-hydroxyethyl methacrylate-N-methacryloyl-(L)-phenylalanine] nanoparticles were used in the adsorption of Bacillus licheniformis a-amylase in a batch system. With an optimized adsorption protocol, a very high loading of 705 mg of enzyme/g nanoparticles was obtained. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The inverse of enzyme affinity for free amylase (181.82 mg/ mL) was higher than that for immobilized enzyme (81.97 mg/mL). Storage stability was found to increase with adsorption. It was observed that the enzyme could be repeatedly adsorbed and desorbed without a significant loss in the adsorption amount or enzyme activity.