A simple colorimetric and fluorometric probe for rapid detection of CN- with large emission shift

Novel förster resonance energy transfer (FRET)-based ratiometric fluorescent probe for detection of cyanides by nucleophilic substitution of aromatic hydrogen (SNArH)

The development of novel fluorescent probes for real-time detection of cyanides (CN-) in environmental and biological systems has become a significant focus in chemical sensing. Particularly, ratiometric fluorescence sensing offers a unique method for precise and quantitative detection of cyanides, even under complex conditions. We report herein the design of a new ratiometric fluorescent probe for cyanides based on modulation of Förster resonance energy transfer (FRET) coupled with novel cyanide-induced nucleophilic substitution of aromatic hydrogen (SNArH). The target probe (R1) is developed by introducing coumarin fluorophores as FRET donors into a 3-nitro-naphthalimide acceptor, which is easily synthesized and exhibits a colorimetric change from colorless to faint yellow and a significant ratiometric fluorescence shift (Δλ = 114 nm) upon cyanide binding. A clear ratiometric signal at I582/I468 was obtained, with a limit of detection of 5.69 μM. The sensing mechanism was confirmed through 1H NMR titration and LC-MS analysis. Additionally, R1-loaded strips were easily prepared, serving as a portable device for detecting CN- with visible color changes. The probe R1 has been successfully utilized for real-time monitoring of cyanide in food materials and water samples. Importantly, fluorescence bioimaging studies in HeLa cells were conducted, demonstrating the probe's capability for ratiometric detection of exogenous CN- in living systems.

Visual detection and discrimination of nerve and blood agents using a dual-site fluorescent probe in living cells and mice

Of all chemical warfare agents (CWAs), only nerve and blood agents cause massive mortality at low concentrations. To better detect and discriminate nerve and blood agents, a reliable detection method is desirable. We report a series of fluorescent probes for nerve and blood agent detection. Among the tested probes, SR-Pip detected nerve and blood agents quickly (within 10 s for nerve agents and 1 min for blood agents). SR-Pip coupled with nerve agent produced a weak orange fluorescence with good sensitivity [limit of detection (LOD)= 5.5 μM]. Upon reaction with blood agent, the fluorescence of SR-Pip changed from orange fluorescence to blue fluorescence with detection limits as low as 9.6 nM. This probe effectively visualised different concentrations of nerve agents in living cells and mice. A portable test kit using SR-Pip instantly detected nerve and blood agents. To the best of our knowledge, SR-Pip is the first fluorescent probe for nerve and blood agent detection.

An innovative fluorescent probe for the detection of cyanide - enhanced sensitivity by controlling its electrostatic potential and suitable for applications such as cell imaging and food analysis

As cyanide is a huge hazard to the environment and human health, the study of the method of detecting low concentrations of cyanide is of great significance. In general, materials with strong positive electrostatic properties can use electrostatic attraction to enrich anions in the water near the materials, then realize rapid detection of low concentration anions by fluorescent probes. In this paper, fluorescent probes PI-S, PI-I and PI-N with cyanide-specific recognition and different charges were synthesized to study the relationship between the charge effect of probes and the sensing sensitivity. Through the zeta potential test and the calculation of the surface electrostatic potential, the positive electricity of PI-S, PI-I and PI-N gradually increased, the ΔG < 0 of the adsorption process gradually decreased, CN- could be aggregated to the vicinity of probes. As a result, the detection limit of the probe was gradually reduced from 1.07 × 10-6 to 5.03 × 10-8 M, the sensitivity was significantly enhanced. Therefore, this is expected to be a new strategy to improve the sensitivity of anion probes by increasing the positive electricity of molecules. In addition, PI-N has good anti-interference ability, short response time and certain application value in cell imaging and identification of endogenous cyanide in food.