Eu³⁺-doped Bovine Serum Albumin-derived Carbon Dots for Ratiometric Fluorescent Detection of Tetracycline

The abuse of antibiotics has become a global concern, thus it is significant to develop simple antibiotic assays. Herein, a novel type of lanthanide-doped bovine serum albumin (BSA) derived carbon dots (BCDs) dubbed Eu-BCDs has been unveiled for ratiometric fluorescent detection of tetracycline (TC), which was formed from the one-step hydrothermal reaction of Eu³⁺ and BSA. Upon challenge with TC, the blue fluorescence of Eu-BCDs at 448 nm was gradually quenched due to the internal filtration effect, while the characteristic red fluorescence of Eu³⁺ at 618 nm was significantly enhanced owning to the antenna effect, leading to the ratiometric fluorescent detection of TC with fast response (2 min), a wide linear dynamic range (0–80 μmol/L), and high selectivity and sensitivity (limit of detection (LOD) of 3 nmol/L). Moreover, Eu-BCDs can be successfully applied for the ratiometric fluorescent detection of TC in environmental and biological samples, such as river water, milk, honey and serum. The Eu-BCDs sensing platform would have great application potential in view of its simple preparation, rapid response, high sensitivity and good selectivity.