A coumarin based ratiometric fluorescent probe for the detection of Cu2+ and mechanochromism as well as application in living cells and vegetables

A single excitation dual emission semi-salamo type multi-functional probe for sensitive pH and Cu2+ detection

pH and Cu2+ ion concentration changes are linked to disorders like Alzheimer's and cancer. Rapid detection of pH and Cu2+ ions is critical for public health and environmental concerns. The semi-salamo-type probe (E)-2-hydroxy-1-naphthaldehyde O-(2-(aminooxy)ethyl) oxime (NSS) demonstrated substantial dual-functional performance, sensing pH change and Cu2+ ions. A single excitation and double emission characteristic on the probe NSS made it distinctive. Probe NSS exhibits pH-dependent excited state intramolecular proton transfer (ESIPT), and its optical properties vary based on the pH environment. Probe NSS detects pH changes from 2 to 11 by changing the "off-on-off" of the excited state intra-molecular proton transfer (ESIPT) mechanism, exhibiting rapid, reversible, and selective responses. In addition, the luminescent salamo-like naphthalene-based probe NSS can coordinate with Cu2+ ions, achieving great selectivity and sensitivity to identify Cu2+ ions with a detection limit of 0.84 ppb (13.2 nM) Probe NSS can detect Cu2+ ions in actual water samples such as tap water and yellow river water. The test strip loaded with probe NSS enabled quick and accurate detection of Cu2+ ions in water samples. Consequently, the versatile salamo-type probe NSS lays the foundation for developing high sensitivity and fast-response dual-mode pH meters as well as Cu2+ sensing.

Cu(II) detection by a fluorometric probe based on thiazoline-amidoquinoline derivative and its application to water and food samples

Two novel fluorescent probes for Cu2+ detection have been developed based on thiazoline-quinoline conjugates bearing a 4-ethynyl-N,N-dimethylaniline unit (QT1 and QT2). QT2 exhibits instantaneous fluorescence quenching of Cu2+ with an emissive change from bright orange to arctic blue under UV light irradiation (365 nm). The plots of I0/I against Cu2+ concentrations show a good linear relationship that ranges from 0 to 50 µM with a coefficient of determination (R2) = 0.9906 and a limit of detection (LOD) of 76 nM, which is considered low (4.84 ppb). A 1:1 complexation between QT2 and Cu2+ was confirmed by UV-Vis titration, ESI-MS, and SC-XRD. The QT2·Cu2+ complex was dissociated by the addition of EDTA. The fluorescence quenching mechanism involves the ligand-to-metal charge transfer (LMCT) of a paramagnetic Cu2+ complex. The QT2 probe on a paper-based strip was used to determine the amount of Cu2+ in water and food samples (shiitake mushrooms and oysters).

All-in-one strategy for the nano-engineering of paper-based bifunctional fluorescent platform for robustly-integrated real-time monitoring of food and drinking-water safety

Cu2+ contamination and food spoilage raise food and drinking water safety issues, posing a serious threat to human health. Besides, Cu2+ and H2S levels indicate excess Cu2+-caused diseases and protein-containing food spoilage. Herein, a coumarin-containing bifunctional paper-based fluorescent platform integrated with a straightforward smartphone color recognition app is developed by an all-in-one strategy. The proposed fluorescent materials can simultaneously detect Cu2+ and H2S for on-demand food and drinking water safety monitoring at home. Specifically, a coumarin-derived fluorescence sensor (referred to as CMIA) with a low detection limit (0.430 μM) and high-selectivity/-sensitivity for Cu2+ is synthesized through a simple one-step route and then loaded onto commercially used cellulose fiber filter paper to engineer a biomass-based fluorescent material (CMIA-FP). The CMIA-FP offers user-friendly, high-precision, fast-responsive, and real-time visual monitoring of Cu2+. Moreover, CMIA forms a chemically stable complex with Cu2+, loaded onto filter paper to prepare another biomass-based fluorescent platform (CMIA-CU-FP) for visual real-time monitoring of H2S. Based on the exquisite composition design, the proposed dual-function paper-based fluorescent materials equipped with a smartphone color recognition program concurrently realize fast, accurate, and easy real-time monitoring of Cu2+ in drinking water and H2S in chicken breast-/shrimp-spoilage, demonstrating an effective detection strategy for the Cu2+ and H2S monitoring and presenting the new type of biomass-based platforms for concentrated reflection of drinking water and food safety.

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

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.