Biocatalytic Performance of pH‐Sensitive Magnetic Nanoparticles Derived from Layer‐by‐Layer Ionic Self‐Assembly of Chitosan with Glucoamylase

Abstract

Based on the characteristics of polycations of chitosan and glucoamylase, which are oppositely charged, they were successfully alternatingly deposited onto the surface of aldehyde-modified Fe3O4 nanoparticles by using a layer-by-layer ion exchange method to form magnetic carriers to construct multilayer films (designated as Fe3O4@(CS/GA)n). The (CS/GA)n film systems were endowed with the pH-dependent properties of chitosan as well as the catalytic activity of glucoamylase. The changes in weight loss and surface chemistry, morphology, and magnetic sensitivity were monitored and verified by UV/Vis spectroscopy, zeta potential, TEM, and a vibrating sample magnetometer. Subsequently, the influence of the number of bilayers, storage stability, pH, temperature, and reusability of Fe3O4@(CS/GA)5 biocatalysts on catalytic activity were investigated. The results from characterization and determination remarkably indicate that Fe3O4@(CS/GA)5 presents excellent catalytic activity, storage stability, pH stability, and reusability in comparison with free enzyme. Fe3O4@(CS/GA)5 retained >60% of its initial activity at 65 °C over 6 h; the optimum temperature and pH also increased to the ranges of 45-65 °C and 2.5-3.5, respectively, and only 27% activity was lost after 10 cycles. This new strategy simplifies the reaction protocol and improves encapsulation efficiency and catalytic activity for new potential applications in biotechnology.

Off-on switching of enzyme activity by near-infrared light-induced photothermal phase transition of nanohybrids

“…GA is an enzyme capable of hydrolyzing starch into glucose ( 32 ). The negatively stained high-resolution transmission electron microscope (HRTEM) image reveals that GA/Pt is highly monodispersed, and the Pt nanoparticle is inside GA.…”

“…We further used PE-GA/Pt 2 for hydrogel photopatterning. In a three-enzyme cascade reaction, PE-GA/Pt 2 catalyzes the hydrolysis of starch into glucose ( 32 ), and then, glucose oxidase (GOx) catalyzes the oxidation of glucose to hydrogen peroxide (H 2 O 2 ) (Fig. 3A) ( 35 ).…”

Nanomaterials as novel supports for the immobilization of amylolytic enzymes and their applications: A review

“…Therefore, such magnetic/CS microspheres with perfect monodispersity would be an ideal support for enzyme immobilization [93]. In a further study, Wang et al [94] obtained an alternative layered assembly of CS and glucoamylase on the surface of aldehyde modified Fe 3 O 4 MNPs via ion exchange method. Five layer immobilized glucoamylase had excellent catalytic activity, storage and pH stability, and reusability as compared to soluble enzyme.…”

“…Glucoamylases immobilized on/ in nanosupports retained remarkably high stability against the inactivation mediated by pH, heat, inhibitors, products, and storage as compared to soluble enzyme. Such immobilized enzyme preparations were found highly stable on prolonged use in the reactors and on repeated uses in batch processes [92][93][94][95][96].…”