Sensitive detection of DMSO/DMF in water, human urine and blood plasma using novel 1,8-naphthalimide-based amphiphilic spectroscopic probes

Abstract

Dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) are industrial toxins that need to be sensed. We synthesized 1,8-naphthalimide-m-benzenesulfonamide (NBS)-bearing probes (1–5) with different pendant chains for sensitive detection of DMSO and DMF. These probes exhibited aggregation-induced emission enhancement with increasing water concentration in ethanol. Among these, monopod probes with a single NBS unit (1–4) selectively showed large fluorescence quenching upon addition of DMSO/DMF in water. Based on this result, we prepared two water-soluble probes (8 and 9) bearing the NBS unit. These probes displayed enhanced sensitivity in detecting DMSO/DMF in water compared to probe 1, showing an extraordinary low LOD of 0.0025% for DMSO and DMF detection in water. Probe 9 was similarly effective at sensitively sensing DMSO/DMF when tap or lake water was used as the medium, and the LOD of this probe was 0.05% when biological fluids such as diluted human urine and blood plasma were used instead of water. According to DLS, FE-SEM and zeta potential studies as well as DFT calculations, disaggregation of probe aggregates and electron transfer from the photo-excited probe to DMSO/DMF are likely both responsible for the high selectivity and sensitivity of this probe in detecting the organic solvents containing a sulfoxide/amide group.