Ratiometric method based on silicon nanodots and Eu³⁺ system for highly-sensitive detection of tetracyclines

A silicon nanodots (SiNDs)-based ratiometric fluorescent sensor was designed to establish highly sensitive and selective method for detection of tetracyclines (TCs). The sensor comprises the blue fluorescence SiNDs were prepared by hydrothermal method synthesis from (3-aminopropyl)triethoxysilane and low-cost diethylenetriaminepentaacetic acid as the precursor, which serve as co-ligands for covalently bond with europium ions (Eu³⁺), and also the internal reference signal. In the presence of TCs, the luminescence intensity of Eu³⁺ was significantly increased, while the luminescence intensity of SiNDs was reduced. The fluorescence intensity ratio of I₆₁₆/I₄₅₀ of the sensor exhibits a sensitive linear range from 0.2 to 20 μM with a detection limit of 3 nM for the detection of TCs. This method was successfully applied to determine the levels of TCs in nature river samples and milk samples with good recoveries ranges from 92.2% to 107.4% and relative standard deviations (RSD, n = 3) was below 5%, providing a promising application future in real samples.