Carbonized zein nanosheets with intrinsic enzyme-mimicking activities and high photothermal conversion efficiency for synergistic cancer therapy.

With the rapid development of biology and nanotechnology, designing nanomaterials with intrinsic enzyme-like activities has attracted huge attention in recent years. Herein, for the first time, we use zein as a new protein precursor to prepare N-rich carbonized zein nanosheets (C-Zein) via facile pyrolysis. Zein is an inert, biodegradable and sustainable natural biopolymer. After high-temperature carbonization, zein can be converted into highly catalytically active C-Zein, which can possess excellent peroxidase- and oxidase-like catalytic activities. Such intrinsic enzyme-like activities of C-Zein are closely related to its graphitization degree, the ratio of graphitic nitrogen and the formation of disordered graphene. Intriguingly, C-Zein also exhibits high photothermal conversion efficiency in the near-infrared (NIR) region. Coupling their unique photothermal and catalytic properties, the as-prepared C-Zein can act as a robust agent for synergistic photothermal-catalytic cancer treatment under the irradiation of NIR light. We expect that this work paves the way to use zein for designing efficient artificial enzymes and accelerate further growth in exploring its new biomedical and pharmaceutical applications.