Facile synthesis of oxidic PEG-modified magnetic polydopamine nanospheres for Candida rugosa lipase immobilization

A versatile method for the design of polydopamine-coated magnetic material with a brush-like structure used for Candida Rugosa lipase (CRL) immobilization was reported in this work. First, polydopamine (PDA) was coated on the surface of Fe3O4 nanospheres (Fe3O4 NPs) with a controllable thickness via dip coating process, and CRL can be immobilized on it directly via covalent bonding. Subsequently, PDA-functionalized Fe3O4 NPs were modified with dialdehyde polyethylene glycol (PEG) to obtain the aldehyde groups, and the brush-like structure of the magnetic supports was formed. After being characterized with various methods, it was verified that the prepared magnetic NPs possessed good monodispersity and displayed high saturation magnetization after modification. Meanwhile, the CRL was immobilized on it covalently, and the enzyme activities such as activity, stability, and reusability were investigated. Significantly, the versatility of polydopamine-inspired chemistry combined with the unique biological nature and tunability with dialdehyde PEG could evoke the efficiency of the CRL, making this a promising coating technique for various bio-applications.