Protein Nanotubes Assembled from Imidazole-Grafted Horseradish Peroxidase Nanogels

Protein assembly, a common phenomenon in nature, plays an important role in the evolution of life. Inspired by nature, assembling protein monomers into delicate nanostructures has emerged as an attractive research area. However, sophisticated protein assemblies usually need complicated designs or templates. In this work, we successfully fabricated protein nanotubes in a facile way by coordination interactions between imidazole-grafted horseradish peroxidase (HRP) nanogels (iHNs) and Cu²⁺. The iHNs were synthesized by polymerization on the surface of HRP by employing vinyl imidazole as a comonomer. By direct addition of Cu²⁺ into iHN solution, protein tubes were therefore formed. The size of the protein tubes could be adjusted by changing the added Cu²⁺ amount, and the mechanism behind the formation of protein nanotubes was elucidated. Furthermore, a highly sensitive H₂O₂ detection system was established based on the protein tubes. This work provides a facile method to construct diverse sophisticated functional protein nanomaterials.