Multi-modal detection methods based on vortex fluid device mediated red-emitting carbon dots for sensitive vitamin B₆ detection in food

Accurate VB₆ quantification in food analysis is hindered by conventional single-signal, short-wavelength methods with poor anti-interference capability and unreliable outcomes. Thus, we develop a long-wavelength, multi-modal, and portable sensing platform for VB₆ detection. The R-CDs are first synthesized via a vortex fluidic device-assisted solvothermal strategy using resazurin and boric acid as precursors, exhibiting uniform size, red emission at 616 nm, and a high quantum yield of 71.5%. The sensing mechanism involves amino-functionalized R-CDs binding VB₆ to form complexes, triggering electron transfer that induces fluorescence quenching, emission blue-shift and reduced UV absorption. Integrating fluorescence, UV, and smartphone-based visual detection, this platform achieves a low limit of detection of 0.87 μg/mL. Moreover, the recoveries (100.09–102.86%) in real samples confirm its practical applicability. This work establishes a multi-modal sensing strategy with cross-validation, offering a versatile paradigm for high-accuracy analyte detection in complex matrices and advancing carbon dot-based sensors.