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Development of high performance biocatalysts generally seeks enhanced specific enzyme activities under intensified reaction conditions. This work reports a novel polydopamine fabricated Fe 3 O 4 nanoparticles for incorporation with enzymes through the formation of flexible spacer arms using dialdehyde starch (DAS). It appeared that the biocompatible microenvironment and flexible tethering at the particle interface could effectively improve performance of the immobilized enzyme. In a test with laccase, such fabricated nanoparticles could reach enzyme loadings as high as 242 mg/g, while retained 69% specific enzyme activity. At the same time, the spacer arm-facilitated immobilization reduced the conformation changes with the control of interfacial action between enzyme and nanoparticles. Furthermore, the immobilized enzyme showed much improved stability against pH and thermal inactivation compared to free laccase. As a result, the immobilized laccase exhibited high degradation efficiency and reusability when tested for removal of 2,4-dichlorophenol and more contaminants from water. The results demonstrated a new strategy in fabricating nanomaterials using bio-based polymers for preparation of high performance biocatalysts. [ABSTRACT FROM AUTHOR]

In this study potato and corn starch were subjected to oxidation, using sodium periodate, to obtain dialdehyde starch (DAS) containing different amount of aldehyde groups. The obtained modified starch samples have been characterized with chemical analysis, scanning electron microscopy (SEM) and ATR-FTIR spectroscopy. Then, the samples were exposed to polychromatic UV radiation and the course of photochemical reaction has been monitored with ATR-FTIR spectroscopy. The surface properties of the native and dialdehyde starch before and after UV-irradiation have been determined by contact angle measurements and calculation of surface free energy. The crystallinity of the samples has been estimated with X-ray diffraction (XRD). It has been proved that the dialdehyded corn starch contained a higher amount of functional groups was more photostable than the oxidized potato starch. Sodium iodide(V), firmly bound to DAS macromolecules, has been found to have a significant effect on the photooxidative degradation of the tested systems. In addition, the mechanism of photoinduced reactions in the dialdehyde starch has been proposed.

In this study potato and corn starch were subjected to oxidation, using sodium periodate, to obtain dialdehyde starch (DAS) containing different amount of aldehyde groups. The obtained modified starch samples have been characterized with chemical analysis, scanning electron microscopy (SEM) and ATR-FTIR spectroscopy. Then, the samples were exposed to polychromatic UV radiation and the course of photochemical reaction has been monitored with ATR-FTIR spectroscopy. The surface properties of the native and dialdehyde starch before and after UV-irradiation have been determined by contact angle measurements and calculation of surface free energy. The crystallinity of the samples has been estimated with X-ray diffraction (XRD). It has been proved that the dialdehyded corn starch contained a higher amount of functional groups was more photostable than the oxidized potato starch. Sodium iodide(V), firmly bound to DAS macromolecules, has been found to have a significant effect on the photooxidative degradation of the tested systems. In addition, the mechanism of photoinduced reactions in the dialdehyde starch has been proposed. [ABSTRACT FROM AUTHOR]