Copper(II) Oxide Spindle-like Nanomotors Decorated with Calcium Peroxide Nanoshell as a New Nanozyme with Photothermal and Chemodynamic Functions Providing ROS Self-Amplification, Glutathione Depletion, and Cu(I)/Cu(II) Recycling

Abstract

Uniform, mesoporous copper(II) oxide nanospindles (CuO NSs) were synthesized via a method based on templated hydrothermal oxidation of copper in the presence of monodisperse poly(glycerol dimethacrylate- co-methacrylic acid) nanoparticles (poly(GDMA- co-MAA) NPs). Subsequent decoration of CuO NSs with a CaO ₂ nanoshell (CuO@CaO ₂ NSs) yielded a nanozyme capable of Cu(I)/Cu(II) redox cycling. Activation of the Cu(I)/Cu(II) cycle by exogenously generated H ₂O ₂ from the CaO ₂ nanoshell significantly enhanced glutathione (GSH) depletion. CuO@CaO ₂ NSs exhibited a 2-fold higher GSH depletion rate compared to pristine CuO NSs. The generation of oxygen due to the catalase (CAT)-like decomposition of H ₂O ₂ by CuO@CaO ₂ NSs resulted in a self-propelled diffusion behavior, characteristic of a H ₂O ₂ fueled nanomotor. These nanostructures exhibited both peroxidase (POD)-like and CAT-like activities and were capable of self-production of H ₂O ₂ in aqueous media via a chemical reaction between the CaO ₂ nanoshell and water. Usage of the self-supplied H ₂O ₂ by the POD-like activity of CuO@CaO ₂ NSs amplified the generation of toxic hydroxyl ( ^•OH) radicals, enhancing the chemodynamic effect within the tumor microenvironment (TME). The CAT-like activity provided a source of self-supplied O ₂ via decomposition of H ₂O ₂ to alleviate hypoxic conditions in the TME. Under near-infrared laser irradiation, CuO@CaO ₂ NSs exhibited photothermal conversion properties, with a temperature elevation of 25 °C. The combined GSH depletion and H ₂O ₂ generation led to a more effective production of ^•OH radicals in the cell culture medium. The chemodynamic function was further enhanced by an elevated temperature. To assess the therapeutic potential, CuO@CaO ₂ NSs loaded with the photosensitizer, chlorine e6 (Ce6), were evaluated against T98G glioblastoma cells. The synergistic combination of photodynamic, photohermal, and chemodynamic modalities using CuO@CaO ₂@Ce6 NSs resulted in cell death higher than 90% under in vitro conditions.