Phenothiazine appended thiophene derivative: a trilateral approach to copper ion detection in living cells and aqueous samples

Abstract

This research paper unveils a fluorescent probe (PTZ-SCN) engineered for the specific detection of Cu²⁺, featuring a 10-ethyl-10H-phenothiazine-3-carbaldehyde and 2-(thiophen-2-yl) acetonitrile moiety. The fluorescence sensing behavior of PTZ-SCN towards various metal cations was scrutinized in CH₃CN : HEPES (9 : 1) buffer aqueous solution. The UV absorbance of PTZ-SCN displayed a distinct red shift in the presence of Cu²⁺ cations, whereas other metal cations did not cause any interference. Similarly, the fluorescence emission of the probe was also only quenched by Cu²⁺ cations. The limit of detection (LOD) was calculated as 1.0461 × 10⁻⁸ M. PTZ-SCN showed the ability to identify Cu²⁺ using the colorimetric method, the fluorometric method and even through visual observation in a trilateral detection. We studied the recognition mechanism of PTZ-SCN for Cu²⁺ using ¹H-NMR, HRMS analysis, and time-dependent density functional theory (TDDFT) calculations. Furthermore, our study encompassed the investigation of PTZ-SCN's practical applicability, bridging the gap from research to real-world implementation. This was achieved by employing test strips and water samples for the detection of Cu²⁺. Additionally, the PTZ-SCN probe's low cytotoxicity and effective imaging properties for Cu²⁺ in living cells were confirmed, indicating that PTZ-SCN shows the potential to serve as a promising probe for detecting Cu²⁺ in vivo.