Immobilization of laccase into magnetic hydrogel nanocomposites and decolorization of methyl orange

In this study, poly(acrylamide)/alginate and poly(acrylamide-N-isopropylacrylamide)/alginate magnetic hydrogel nanocomposites were synthesized using Fe3O4 nanoparticles. Magnetic hydrogel nanocomposites were characterized by scanning electron microscopy and energy dispersive spectrometry (SEM/EDS), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction method (XRD), thermogravimetric analysis (TGA), electron paramagnetic resonance spectroscopy (EPR) and vibrating sample magnetometry (VSM). The results indicated that magnetic hydrogel nanocomposites are superparamagnetic, the size of Fe3O4 nanoparticles are ~16 nm in the magnetic hydrogel nanocomposites and they have the same spinel structure with naked Fe3O4 nanoparticles. Laccase enzyme was immobilized using entrapment method in these magnetic hydrogel nanocomposites. The effect of pH, temperature, substrate concentration and storage time on the activities of free and immobilized laccases were investigated. The immobilization improved laccase stability for pH, temperature and storage time. Percent decolorization of Methyl Orange which was choosed as a model dye by immobilized laccases were found between %43 - %48 and %74- %72 without mediator and in the presence of mediator, respectively.