A bimetallic synergistic effect-triggered colorimetric sensor for rapid tumor screening

Hydrogen peroxide (H₂O₂) is a key signaling molecule in tumor progression, making its real-time detection vital for elucidating the complex mechanisms underlying tumorigenesis. Herein, we report a rationally colorimetric sensing platform for rapid tumor screening, leveraging the bifunctional enzyme-like activity of a heterostructured h-NiO/CoO/C nanosphere. Notably, by activating electron structure reconstruction with abundant oxygen vacancies and utilizing a dual-non-precious-metal method, h-NiO/CoO/C nanosphere enhances catalytic performance beyond the limitations of single-non-precious-metal-doped nanomaterials (e.g., NiO/C and CoO/C), remarkably boosting peroxidase (POD)-mimicking catalytic activities. Intriguingly, h-NiO/CoO/C shows a substantial enhancement in POD capability in comparison with single NiO/C and CoO/C, indicating superior sensitivity for monitoring endogenous H₂O₂. By integrating h-NiO/CoO/C with the chromogenic reaction principle, a highly rapid and sensitive endogenous H₂O₂ sensor is constructed. Furthermore, the resulting color change is analyzed via a smartphone application to provide instant, semiquantitative data. The smartphone-based colorimetric detection of H₂O₂ is realized via mutual verification by these two strategies. The assay data suggested that the POD-mimicking catalytic activity determination range is 0.01-2.8 mM, with a low limit of detection of 7.5 μM. This study demonstrates the rational design of highly efficient POD-mimicking nanozymes by engineering their structure-performance relationship, paving a new avenue for developing advanced nanozymes and providing a rapid, accessible toolkit for tumor screening.