Application of molecularly imprinted polymers on carbon dots for fluorescence detection of bumetanide in adulterated dietary supplements: instrumental and paper-based approaches.

Bumetanide (BUM) is a strong loop diuretic that is commonly abused as an illicit adulterant in weight-loss dietary supplements to create rapid fluid loss and conceal performance-enhancing chemicals. Considering the health hazards linked with its uncontrolled use, there is an urgent demand to find quick and readily available screening instruments. Herein, we have constructed a very selective and sensitive fluorescent probe, whereby we have incorporated water-soluble carbon dots (CDs) into a molecular imprinted polymer (MIP) platform (CDs@MIP). The prepared probe had strong fluorescence quenching at different bumetanide concentrations with a good linearity (R2 = 0.9996) and a limit of detection (LOD) of 2.18 µM. Besides, the CDs@MIP were integrated successfully into a portable paper-based analytical device (PAD) patterned with a correction-pen strategy and capable of smartphone-based fluorescence data analysis, to permit on-site analysis. The two-detection approach fluorescent system was successfully used for the identification of BUM in complicated dietary supplements, such as herbal teas, capsules, and sachets. The proposed instrument-based and paper-based sensing strategies provide cost-effective, end-user-friendly, and durable remedies to the regular screening and point-of-care screening of illicit adulterants in dietary supplements.