Sensitive Determination of Ofloxacin by Molecularly Imprinted Polymers Containing Ionic Liquid Functionalized Carbon Quantum Dots and Europium Ion

Antibiotic pollution has become a serious problem due to concerns about sustainability and the environment. Ofloxacin (OFL) is an important antibiotic, which is used widely in the treatment of human and animal diseases, resulting in large-scale production and aggregation in the environment. A facile and high-performance method for detecting OFL is valuable for practical reasons. Herein, a novel CDs/Eu3+-based molecularly imprinted polymer fluorescent probe (CDs/Eu3+@MIP) was successfully synthesized using ionic liquid-functionalized carbon dots (IL@CDs) as the functional monomer and ofloxacin (OFL) as the template molecule. This probe exhibited excellent fluorescent properties. Under optimal conditions, CDs/Eu3+@MIP displayed outstanding detection performance for OFL. The limit of detection was as low as 0.25 nM. Furthermore, the detection mechanism of the fluorescent probe was also discussed. The lanthanide luminescence intensity increased significantly with the addition of OFL, which was observed as a deeper red color with the naked eye. The mechanism of detecting OFL was exposure to the efficient energy transfer from OFL to Eu3+ through the antenna effect. In particular, the probe demonstrated high selectivity toward OFL due to combining molecular imprinting technology. This first reported fluorescent sensing material based on CDs/Eu3+@MIP provides a promising scheme for highly sensitive detection of antibiotic OFL.