Rational Design of Conducting Polymer-Derived Tubular Carbon Nanoreactors for Enhanced Enzyme-like Catalysis and Total Antioxidant Capacity Bioassay Application

The design of void-confined tubular nanostructures has aroused significant interest for catalytic applications because of their distinct microenvironment to modulate the reaction kinetics. Herein, we propose a facile wrapping-pyrolysis strategy to confine Fe-0 nanoparticles (Fe NPs) inside N-doped carbon nanotubes (Fe@NC NTs) derived from Fe2O3@polypyrrole (PPy) core-sheath nanofibers (NFs). The resultant Fe@NC NTs can act as efficient enzyme mimics and exhibit a significantly higher peroxidase (POD)-like catalytic activity than unconfined Fe NPs and bare NC NTs. Kinetic experiments demonstrate that the optimized void structure benefits the affinity with the POD substrates and achieves excellent catalytic efficiency. The mechanism study reveals that the generation of .OH from H2O2 endows Fe@NC NTs with excellent POD-like performance. Furthermore, we develop a total antioxidant capacity (TAC) sensing platform on account of this efficient POD-like system, expanding their applications in the field of food safety and human healthcare.