pH-guided fluorescent sensing probe for the discriminative detection of Cl− and Br− in human serum

Abstract

The fluctuation of the halide ion concentration in human serum is of a high clinical implication. The measurement of Cl− in human serum samples is important because Cl− is a major constituent of human serum and certain Cl− levels are indicators of many acute diseases. Real-time monitoring of Br− levels in human serum samples from patients ingesting Br− salt-based antiepileptic drugs is important to regulate potential adverse drug effects. In this study, we developed a fluorescent probe for the discriminative sensing of Cl− and Br− using a naphthalimide–benzimidazole conjugate-based Ag+ complex (L1-Ag+ complex) by exploiting the strong interaction between Ag+ and halide ions with selectivity control by pH variation. The probe exhibited a dual function of detecting Cl− and Br− at pH levels of 4.5 and 8.0, respectively. Under this two pH conditions, the probe showed a high sensitivity (limit of detection (LOD) = 43 and 5 μM for Cl− and Br−, respectively) and selectivity toward Cl− and Br−. Importantly, the probe could be applied in the quantification of Cl− and Br− levels in human serum samples under two conditions: Cl− in normal human serum and Br− in the serum-mimicking that of epileptic patients during medication. © 2022