Cysteine carbon dots/Au3+ system for dual-mode detection of epinephrine and discrimination of different catecholamines with PCA

Accurate and convenient detection of epinephrine (Ep) is critical for diagnosing neurological disorders and monitoring emergency medications. In this study, a ratiometric fluorescent platform was developed for Ep detection by integrating cysteine-functionalized carbon dots with gold ions (Cys-CDs/Au 3+ ). The platform relied on Au 3+ -mediated oxidation of epinephrine to generate a fluorescence response, which is further enhanced by boric acid. Two detection modes were established: fluorescence assay and smartphone-assisted RGB analysis, demonstrating limits of detection (LOD) of 0.12 μM and 0.85 μM, respectively. The platform enabled accurate quantification of Ep in injections and artificial cerebrospinal fluid (aCSF). Furthermore, principal component analysis (PCA) facilitated discrimination among multiple catecholamines by reducing the dimensionality of fluorescence spectral data. This work provides a versatile platform for Ep detection and catecholamine discrimination.