One-pot method of recyclable lipase-nanocatalyst based on chitosan magnetic nanomaterial for ethyl levulinate synthesis

Carrier, immobilization method and conditions are the most important factors affecting the performance of immobilized lipase. In this study, MNP@CTS is successfully prepared via an improved hydrothermal method combined with ion condensation. Then, we creatively adopt one-pot method, combining electrostatic adsorption with chemical crosslinking, to prepare lipase-nanocatalyst with excellent performance under mild conditions. MNP@CTS and lipase-nanocatalyst are characterized by FTIR, SEM, HRTEM, CLSM, CD, etc, the optimal conditions are explored in detail too. Lipase-nanocatalyst is 189 nm, and the loading ratio of free lipase is up to 67.6%. Compared with free lipase, specific activity is increased by 2.9 times, and it also broadens toleration to pH, thermal, organic solvents. In addition, lipase-nanocatalyst exhibits high storage stability and reusability. The residual activity is approximately 92.3% after the 10th recycle, and the cumulative catalytic activity is 13.4 times than that of free lipase. Finally, lipase-nanocatalyst is used to synthesize ethyl levulinate, with a production ratio of 68.6% for the first recycle, and the total output of EL is 12.9 times than that of free lipase after ten cycles. Thus, our findings provide a foundation for lipase-nanocatalyst showing several attractive features, such as easy preparation, excellent catalytic activity, good stability and reusability.