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

Abstract

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.