Recyclable malate dehydrogenase nanocatalyst based on chitosan for oxaloacetic acid green synthesis

Abstract

Biocatalysis is a new, efficient and green method for oxaloacetic acid (OAA) synthesis. However, malate dehydrogenase (MDH) is unstable, which is the bottleneck for biocatalysis. Immobilization is a good strategy to solve this problem. In this study, chitosan magnetic nanoparticles were used as carriers, and the MDH-nanocatalyst was prepared by a one-pot method combined with electrostatic adsorption and covalent binding. The main factors affecting the performance of the MDH-nanocatalyst were studied in detail, and the optimum preparation process and conditions were obtained. The results show that the hydration particle size of MDH-nanocatalyst is 164 nm in size, with a PDI value of 0.458. It exhibited broad stability against various pH, thermal, organic solvent, metal ion and storage conditions. Finally, the MDH-nanocatalyst was used to synthesize OAA with a yield of 97.6 %. It also showed good circularity, with a remaining catalytic activity of 67.8 % after the 10th cycle. Thus, our findings demonstrate that MDH-nanocatalysts have several attractive features, such as easy preparation, excellent stability and reusability. Therefore, this work provides a foundation for the potential application of these nanocatalysts in the green synthesis of OAA.