Aggregation-induced emission carbon dots-based dual-mode sensor for smartphone-assisted rapid detection of putrescine in shrimp.

Accurate on-site detection of food spoilage indicators constitutes a fundamental requirement for evaluating food freshness and ensuring safety. In this work, a dual-mode sensor (CDs/AuNCs) integrating carbon dots and gold nanoclusters was reported, which enabled the rapid detection of putrescine within 20 s. Interaction of putrescine with the sensor led to increased fluorescence intensity of CDs at 430 nm and 525 nm originating from aggregation-induced emission effect and inner filter effect with AuNCs. The system achieved a low limit of detection (LOD) of 0.439 μmol/L in the range of 1-80 μmol/L, accompanied by good selectivity and resistance to interference, as well as outstanding repeatability of measurement (RSD < 1.08%). Furthermore, CDs/AuNCs demonstrated a good colorimetric linear response to putrescine with a LOD of 0.720 μmol/L. An integrated smartphone-based colorimetric and fluorescence platform was developed for rapid visual quantification of putrescine in shrimp meat, demonstrating its potential in real-time seafood spoilage monitoring.