Carbon dots-based 'two-pronged' strategy for dual-mode rifampicin sensing: From laboratory to smartphone-assisted field testing.

Rifampicin (RIF), a critical anti-tuberculosis drug and broad-spectrum antibiotic, poses significant risks to food safety and public health when misused. To ensure efficient monitoring, we developed a 'two-pronged' sensing strategy using yellowish-green fluorescent carbon dots (CDs) for both laboratory analysis and on-site detection. The CDs exhibit excitation-independent photoluminescence and robust photostability. In the laboratory mode, RIF selectively quenches the CDs' fluorescence, achieving a detection limit (LOD) of 0.67 μM (linear range: 325 μM). For on-site application, a paper-based sensor was constructed by depositing CDs onto filter paper. Quantitative analysis of RIF on test strips was realized via a custom-developed WeChat mini-program, 'RIF Tester', which converts colorimetric changes into concentrations under ambient light, achieving high recoveries (88.7% ∼ 110.0%) across a 0-90 μM range. This study marks the first development of a smartphone-integrated, instrument-free paper platform for rapid RIF monitoring, offering a powerful tool for resource-limited settings.