Modification of Fe₃O₄ magnetic nanoparticles by L-dopa or dopamine as an enzyme support

Abstract

Fe₃O₄ magnetic nanoparticles were prepared by co-precipitation of Fe²⁺ and Fe³⁺ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe₃O₄ magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin (EC: 3.4.21.4) on Fe₃O₄ magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.

Keywords

Fe₃O₄ magnetic nanoparticles / modification / trypsin / immobilization / L-dopa / dopamine

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