Fluorescence Based Epinephrine Detection Using CeCr@CQDs. Towards Advanced Biomolecule Sensing with Smartphone Sensing.

Carbon Quantum dots (CQDs) exhibit excellent fluorescence properties, including high photostability, broad absorption cross-section, and tunable emission spectra, making them promising candidates for sensing applications. This study explores the development of cerium-chromium co-doped CQDs (CeCr@CQDs) to enhance their interaction with specific hormones, particularly epinephrine (Eph), resulting in measurable changes in fluorescence emission. CeCr@CQDs were synthesized via a hydrothermal method and comprehensively characterized using XRD, XPS, SEM, HR-TEM, FT-IR, UV-Visible spectroscopy, and photoluminescence (PL) analysis. A fluorescence-based sensing platform was established for the selective and sensitive detection of Eph, leveraging the dynamic quenching mechanism responsible for fluorescence intensity reduction upon Eph binding. The sensor demonstrated a linear response to Eph concentration ranging from 0 to 41 µM, with a correlation coefficient of 0.9946 and limit of detection (LOD) is 1.48 µM. Additionally, perceptible color changes upon Eph addition were effectively monitored using an RGB color detector smartphone application. These results highlight the potential of CeCr@CQDs for advanced diagnostic applications and the development of CQD-based sensors for hormone detection and related biochemical assays.