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

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. • A dual-functional fluorescent probe ( L1 -Ag + complex) was developed for discriminative detection of Cl − and Br − . • The probe could be utilized for discriminative detection of Cl − and Br − using a single probe by pH control. • The probe was applicable to determination of Cl − and Br − level in human serum.