Immobilization of lipase by dialdehyde cellulose crosslinked magnetic nanoparticles

Cellulose microcrystalline (MCC) was widely used in pharmaceutical and chemical industries because of its low degree of polymerization and large specific surface area. As its modified form, dialdehyde cellulose (DAC) was used for cross-linking and immobilizing Rhizopus lipase together with magnetic nanoparticles (MNPs) due to its active aldehyde groups. In this study, in order to maintain the original enzyme activity as much as possible and improve the stability of lipase, the Rhizopus lipase was successfully immobilized on the magnetic dialdehyde cellulose nanoparticles (MDC). Specifically, the immobilization conditions including dosage of DAC, concentration of enzyme, immobilization time and temperature together with pH value of the reaction medium were optimized. Maximum immobilization yield (60.03 +/- 0.49%) and recovery activity (88.88 +/- 0.61%) can be obtained under the optimal process conditions. The changes in secondary structures of immobilized enzyme revealed the increment in conformational rigidity, which can be reflected in temperature and pH stability as well as tolerance of organic reagents. Additionally, the recovery activity of immobilized enzyme still reached 50.60 +/- 0.59% after 30 d of storage and 52.10 +/- 0.57% retained after 6 cycles. These results indicated the ideal application prospect of MDC in immobilized enzymes.

Automated summary

The study successfully immobilized Rhizopus lipase on magnetic dialdehyde cellulose nanoparticles, optimizing the immobilization conditions to improve enzyme stability and activity. Changes in the secondary structures of the immobilized enzyme revealed increased conformational rigidity, leading to enhanced stability at different temperatures and pH levels, as well as improved tolerance to organic reagents. After storage for 30 days and 6 cycles, the immobilized enzyme still retained high recovery activity, indicating the promising application prospect of MDC in immobilized enzymes.