Newly Synthesized Multifunctional Biopolymer Coated Magnetic Core/Shell Fe 3 O 4 @Au Nanoparticles for Evaluation of L-asparaginase Immobilization

The immobilization strategy can promote greater enzyme utilization in applications by improving the overall stability and reusability of the enzyme. In this work, the L-asparaginase (L-ASNase) obtained from Escherichia coli was chosen as a model enzyme and immobilized onto the Fe 3 O 4 @Au-carboxymethyl chitosan (CMC) magnetic nanoparticles (MNPs) through adsorption. TEM, SEM, FT-IR, XRD, EDS, and TGA analyses were performed to examine the structure with and without L-ASNase. The yield of immobilized L-ASNase on Fe 3 O 4 @Au-CMC was found to be 68%. The biochemical properties such as optimum pH, optimum temperature, reusability, and thermal stability of the Fe 3 O 4 @Au-CMC/L-ASNase were comprehensively investigated. For instance, Fe 3 O 4 @Au-CMC/L-ASNase reached maximum activity at pH 7.0 and the optimum temperature was found to be 50 °C. The noticeably lower Ea value of the Fe 3 O 4 @Au-CMC/L-ASNase revealed the enhanced catalytic activity of this enzyme after immobilization. The Km and Vmax values were 3.27 ± 0.48 mM, and 51.54 ± 0.51 μmol min −1 for Fe 3 O 4 @Au-CMC/L-ASNase, respectively, which means good substrate affinity. The Fe 3 O 4 @Au-CMC/L-ASNase retained 65% of its initial activity even after 90 min at 60 °C. Moreover, it maintained more than 75% of its original activity after 10 cycles, indicating its excellent reusability. The results obtained suggested that this investigation highlights the use of MNPs as a support for the development of more economical and sustainable immobilized enzyme systems.