MoS₂ QDs-Based sensor for measurement of fluazinam with triple signal output

In this study, direct detection of fluazinam was realized using a fluorescent sensor using disulfide quantum dots (MoS₂ QDs) via inner filter effect (IFE). The maximum excitation of as-prepared MoS₂ QDs presented a complementary spectral-overlap with the maximum absorption of fluazinam. Thus the occurrence of inner filter effect led to the significant fluorescence quenching of MoS₂ QDs. Additionally, fluorescent quenching efficiency of MoS₂ QDs could be enhanced by the effects of π-π stacking, hydrogen bond and electrostatic interaction between fluazinam and MoS₂ QDs, and these non-chemical bond responses also promoted the selectivity for fluazinam detection. Under the optimum conditions, the IFE-based fluorescent sensor exhibited a relative wide linear range from 50 nM to 25 μM with the LOD of 2.53 nM (S/N = 3). In addition, a paper-based sensor was established by cross-linking the MoS₂ QDs into cellulose membrane for naked-eyed detection and digital analysis of fluazinam. The paper-based sensor presented a liner range from 10 μM to 800 μM for fluazinam detection with the LOD of 2.26 μM. Additionally, the acceptable recoveries were obtained for fluazinam detection in the spiked samples of tomato, potato and cucumber, indicating that the proposed method provided an effective sensing platform for real applications of fluazinam detection in food safety.