A Ce-Involved MOF@Nanozyme Probe Empowers Programmable Centrifugal Microfluidics for Integrated Immunoassay

Pathogenic bacteria pose significant threats to public health, and their rapid and sensitive detection methods are urgently needed. Here, we developed a hybrid metal-organic framework nanozyme (Ce/Zr-UiO 66@CeO2) with high peroxidase-like activity for colorimetric biosensing that was integrated into a programmable centrifugal microfluidic chip, enabling rapid, sensitive, and automated detection of Salmonella. The Ce/Zr-UiO 66@CeO2 leveraged the structural stability of UiO 66 to resist matrix interference, while the doped Ce species and CeO2 nanoparticles provided abundant oxygen vacancies and efficient Ce3+/Ce4+ redox cycling to enhance catalytic performance. The Salmonella was labeled with magnetic nanoparticles and Ce/Zr-UiO 66@CeO2 to form the sandwich complexes, which initiated a catalytic colorimetric reaction. The programmable differential centrifugal microfluidic chip was capable of simultaneous reagent-sequential release, bacterial immune reaction, and signal-quantitative detection, with no need for external pumps. In this manner, this integrated biosensor was able to detect Salmonella as low as 46 CFU/mL in 28 min, which was 2517-fold more sensitive than ELISA. The recovery rates ranged from 80.67 to 113.72%, confirming its high robustness across diverse food matrices. This platform represents a promising all-in-one biosensing strategy for strengthening food safety.