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.