Mussel-Inspired Electro-oxidation-Modified Three-Dimensional Printed Carriers for a Versatile Enzyme Immobilization Approach

Conventional enzyme immobilization approaches can only immobilize certain specific enzymes with poor generality. Attempts to improve the universality of enzyme types tend to impart them with more enzymatic catalysis applications. Here, inspired by mussel adhesive proteins, we present a novel eco-friendly surface carrier that was 3D printed and modified by electro-oxidation for enzyme immobilization. The carrier was fabricated through 3D printing by transforming acrylonitrile butadiene styrene (ABS) material into a suitable structure (3DABS). Then, electro-oxidative modification was performed on the surface to form a polydopamine (PDA) coating (3DABS-PDA). The desired structures for the enzyme immobilization carriers were obtained through 3D printing technology, while electro-oxidation modification of the surface provided numerous and firmly covalent binding sites. Based on these features, we have demonstrated that 3D printed and electro-oxidation-modified carriers could be applied to immobilize different types of enzymes. The loading capacity of all immobilized enzymes (galV, EG5C-1, XynLK9, and kdcA) exceeded 25 mg·g^-1 (37.7 mg·g^-1 for galV), and after 10 reuse cycles, the substrate conversion rate of 3DABS-PDA@galV was still over 85%. The carriers can be reused after simple processing. These results indicate that 3DABS-PDA provides an efficient, sustainable, and versatile approach for enzyme immobilization and exhibits excellent value in various enzymatic catalysis applications.