Construction of robust protein nanocage frameworks with superior peroxidase-like activity for dye degradation and...

Developing robust and highly active peroxidase mimetics with a well-defined structure for advancing environmental remediation remains a challenge. Herein, we built a protein engineering method to construct stable three-dimensional (3D) protein nanocage frameworks with excellent peroxidase-like activity by using Escherichia coli bacterioferritin (EcBfr) dimers as building blocks, which consists of three steps. The first step corresponds to the construction of robust EcBfr nanocage (3DY) through introducing π-π interactions at its C₃ interfaces. Next, integration of 12 hemin molecules into the C₂ interfaces of 3DY constructed protein nanocage with coaxial bis-methionine ligands represents the second step. The resultant protein nanocage (3DY@heme) exhibits excellent peroxidase (POD)-like activity over natural horseradish peroxidase, with an enhanced catalytic activity along with remarkable resistance to thermal and chemical denaturation. Benefiting from its POD-like activity, 3DY@heme is able to efficiently catalyze the oxidative degradation of triphenylmethane dyes, including crystal violet and basic fuchsin. To enhance the recyclability of 3DY@heme, its C₄ interfaces were also engineered by introducing π-π interactions to drive protein nanocages to generate 3D frameworks, corresponding the third step. These constructed 3D frameworks achieved efficient adsorption of dye, and enable facile catalyst recovery and maintain significant activity over 5 degradation cycles. This work represents a hierarchical design for construction of a multi-functional protein nanocage platform with custom-tailored applications.