Carbon quantum dots derived from marine Eucheuma denticulatum for the efficient and sensitive detection of tetracycline

In this study, Eucheuma denticulatum marine algae were used as the raw material to prepare Eucheuma denticulatum-derived carbon quantum dots (E-CQDs) via a mild chemical oxidation method. The E-CQDs demonstrated good stability and water solubility owing to the presence of hydroxyl groups on the surface. The structure and chemical composition of the E-CQDs were characterized by three means, including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The E-CQDs maintained exceptional stability under varying ion concentrations, pH levels, ultraviolet (UV) irradiation durations, and temperatures. The fluorescence quenching effect of tetracycline (TC) on the E-CQDs was utilized to establish a sensitive and selective TC fluorescence detection method. The mechanism of the TC quenching of the fluorescence of E-CQDs involved an internal filtration effect and dynamic quenching. At the TC concentration of 20–100 μM, the fluorescence intensity showed an excellent linear relationship (R² = 0.997); the limit of detection and quantity was 0.47 μM and 1.57 μM, respectively. These results revealed that this method for TC detection offers good selectivity and immunity to interference.