A dual-channel luminescent signal readout nanoprobe for rapid monitoring of biogenic amines in milk and yogurt

As biologically active small molecular, biogenic amines (BAs) could be served as an important index of food spoilage and contamination. In addition, excessive intake of biogenic amines usually can cause a serious impact on human health. Therefore, it is of great significance to establish a reliable, sensitive, and non-invasive method for the detection of biogenic amines in foods. To address the above problems, optical sensing method utilizing dual-channel fluorescence outputs could be considered as a powerful technique, which can achieve high accuracy and even visual detection. Herein, we have demonstrated for the first time the use of a dual-channel luminescent signal readout nanoprobe o-CDs@methyl red (CDs stands for carbon dots) for rapid, sensitive, and visual detection of biogenic amines. Such probe was prepared by covalently modifying methyl red on NH₂-rich carbon dots, in which o-CDs served as a reference signal and methyl red acted as a signal report unit for BAs. Upon the addition of BAs, the fluorescence intensity of methyl red increases, while that of o-CDs remains almost unchanged. It was found that such fluorescence platform can detect tyramine with high sensitivity (LOD: 0.01 μM) and fast response (30 s). More importantly, the proposed method can be successfully applied for biogenic amines detection in real milk and yogurt samples, indicating that the as-prepared probe holds the further potential for practical application in control and monitoring of food quality and freshness.