Advanced fluorescent carbon dots for quantitative detection of Sudan Red via inner filter effect mechanism

Food safety concerns regarding Sudan Red, a carcinogenic dye, necessitate effective detection methods. This study introduces S, P co-doped blue-emitting carbon dots (BSP-CDs), synthesized via a one-pot hydrothermal method using asparagine as the carbon source. BSP-CDs exhibit excellent optical properties, environmental stability, and selective fluorescence quenching due to the inner filter effect. These properties were utilized to develop a sensitive and rapid “on-off” fluorescence sensing system for Sudan Red detection. The sensor demonstrated a linear detection range of 50–175 μM and a detection limit of 2.11 μM, with high accuracy and recovery rates in real-world water samples. This work offers a green, economical, and highly reproducible approach for Sudan Red monitoring, with significant implications for food safety and environmental protection.