Relay detection of Cu²⁺ and bovine serum albumin by a dansyl derivative-based fluorescent probe

A dansyl derivative-based fluorescent probe, namely, DGly, was developed for relay detection of Cu²⁺ and bovine serum albumin (BSA) with high selectivity and sensitivity. The fluorescence intensity of DGly at 540 nm displayed "on-off-on" phenomenonafter Cu²⁺ and BSA were added in sequence. Correspondingly, the solution color changed from yellow to dark and then to yellowish white under 365 nm UV light irradiation; thus, the solution could be detected by the naked eye. The association constant of DGly-Cu²⁺ was stronger than that of DGly-BSA and DGly-Cu²⁺-BSA. Hence, BSA was detected after a complex was formed between DGly and Cu²⁺. The relay detection of Cu²⁺ and BSA was not influenced by other competitive interferents, and the detection limits of Cu²⁺ and BSA were 1.32 and 0.26 μM, respectively. Analysis of Cu²⁺ in real water samples validated the detection performance of the method proposed herein; it achieved satisfactory recovery and relative standard deviation values. This work demonstrated that introducing metal ions can be an effective way to improve the sensitivity of BSA detection.