Recyclable Magnetic Fluorescence Sensor Based on Fe3O4 and Carbon Dots for Detection and Purification of Methcathinone in Sewage

Sensitive, rapid, and low-cost detection of drug traces in sewage is very important for drug monitoring and control. In this study, a dual functional and recyclable magnetic fluorescent molecularly imprinted polymers (MFMIPs) sensor with high sensitivity for rapid detection and purification of methcathinone in sewage was developed. MFMIPs was prepared via molecular imprinting and conjugation with carbon dots as a fluorescent reporter on Fe3O4 (Fe3O4-MIPs@ CDs). With strong recognition and adsorption toward methcathinone by the specific cavities on the surface of MFMIPs, the fluorescence of the sensor could dramatically be quenched once anchored with methcathinone. Under optimal conditions, the MFMIPs sensor presented high sensitivity with a linear range of 0.5-100 nM and a detection limit of 0.2 nM, which would be used to monitor drug prevalence and consumption within a certain region. This sensor was applied to the assay of methcathinone in sewage samples collected from Yuebeiyuan, Yanghu, and Xujiahu sewage pumping stations of Yuelu District. The calculated concentrations of methcathinone were 4.80, 15.33, and 8.59 nM in sewage samples, which were in good agreement with data tested by LC-MS/MS. For another function, MFMIPs exhibited purification toward methcathinone and the adsorption capacity was about 0.27 mg/g in a real sewage sample. Moreover, the sensor could be recycled and reused at least five times with the aid of an external magnetic field. Collectively, with good analytical performance and excellent recognition and selectivity to methcathinone, the proposed sensing system based on the magnetic core and molecularly imprinted polymers would open a door to establish highly sensitive and effective sensing systems for sewage analysis and purification.

Automated summary

In this study, a dual functional and recyclable magnetic fluorescent molecularly imprinted polymers (MFMIPs) sensor was developed for sensitive and rapid detection and purification of methcathinone in sewage. The sensor exhibited high sensitivity and selectivity, and could be used for monitoring drug prevalence and consumption in a certain region, as well as the assay of methcathinone in sewage samples. The MFMIPs sensor also showed purification ability towards methcathinone and could be recycled multiple times with the aid of an external magnetic field. This sensing system based on magnetic core and molecularly imprinted polymers has great potential for sewage analysis and purification.