MOFs-derived CoO@MnO@Carbon dots with enhanced nanozymes activity for photoelectrochemical detection of cancer cells in whole blood.

Nanozymes have attracted widespread attention, and rationally designing high-activity nanozymes to improve their application performance are a long-term objective. Herein, taking metal-organic frameworks-derived CoO polyhedron with large surface area and high porosity as nanoconfinement carriers, CoO@MnO@CDs polyhedron was successfully synthesized by the room-temperature reduction of MnO ions and physical load of carbon dots (CDs). Through cancer cells-triggered double antibody sandwich strategy, the CoO@MnO@CDs polyhedron were introduced to the TiO nanoparticle (NPs) modified electrode, leading to the decreased photocurrent. The CoO@MnO@CDs polyhedron can not only quench the photocurrent of TiO NPs, also act as nanozymes to catalyze precipitates. Moreover, the precipitates can not only reduce the photoelectrochemical (PEC) response, also increase the quenching capacity of the CoO@MnO@CDs polyhedron. Additionally, the steric hindrance effect of the CoO@MnO@CDs-Ab conjugates further weaken the photocurrent. Based on the multifunctional CoO@MnO@CDs polyhedron, the proposed PEC biosensor for the detection of A549 cancer cells exhibits a wide linear range from 10 to 10 cells/mL and a low detection limit of 11 cells/mL. Furthermore, this strategy can differentiate between lung cancer patients and healthy individuals. The designed multifunctional CoO@MnO@CDs nanozymes provide a new horizon for PEC detection of cancer cells, and may have great potential in early clinical diagnosis and biomedical research.