Polydopamine-mediated synthesis of core-shell gold@calcium phosphate nanoparticles for enzyme immobilization

Considerable efforts have been made to develop reliable immobilization approaches to improve enzyme stability and reusability. However, relatively complicated preparation often leads to compromised enzyme activity. This study reports a facile method of retaining full enzymatic activity by immobilizing glucose oxidase (GOx) into core-shell nanoparticles with polydopamine (PDA) sandwiched between a gold nanoparticle (Au NP) core and a calcium phosphate (CaP) shell (Au@PDA@CaP). The strong adhesion of PDA on Au NPs and its metal chelating properties directed the preferential growth of the CaP shell on the Au NPs, leading to well-dispersed and uniform nanohybrids. Concurrent loading of GOx during the growth of CaP held the key to the successful immobilization of GOx. As a result, Au@PDA@CaP-immobilized GOx had similar activity but better resistance against heating, long-term storage and repeated uses compared to free GOx. This work provides a green strategy for constructing nanobiocatalysts with high enzyme activity and stability.