A green facile fluorescent sensor based on APTES-modified carbon quantum dots coupled with molecular imprinting for efficient detection of metronidazole in aqueous environment

Abstract

Metronidazole (MTZ) as a widely used antibiotic of the nitro-imidazole class to treat infections in both humans and animals, is found to be toxic, mutagenic, carcinogenic and poses a risk to aquatic life and human health via the food chain. An eco-green sustainable and novel APTES-CQDs@MIPs fluorescent sensor was developed with a cost-effective hydrothermal method from APTES and waste orange peels, coupled with molecular imprinting using reverse micro-emulsion for rapid and accurate detection of MTZ in water samples. APTES-CQDs achieved simultaneous carbonization, nitrogen doping, and silica-based passivation, eliminated toxic chemicals, and demonstrated zero waste. The sensor response time was 1 min upon rebinding with MTZ and the fluorescence quenching mechanism was proposed to be charge transfer and static quenching. The APTES-CQDs@MIPs sensor had exceptional reproducibility (RSD 3.45 %) and showed excellent sensitivity and selectivity towards MTZ with a linear concentration range of 0.17–40.00 μM (R² = 0.997), and the detection limit of 0.05 μM. The imprinting factor (IF) reached 4.67 and recycle efficiency achieved over 88 % up to five cycles. The constructed fluorescent probe demonstrated comparable results to other reported methods, with recoveries of 95.1–108.2 %. The sensor has the advantages of simplicity, excellent selectivity, superior sensitivity, good reproducibility, stability, and recyclability.