Double emission fluorescence probes based on unconventional fluorescent molecules and fluorescein isothiocyanate for ClO− and Cu2+ detection

Fluorescent probes for imaging: a focus on atherosclerosis

Atherosclerosis, as a chronic cardiovascular disease driven by inflammation, can lead to arterial stenosis and thrombosis, which seriously threatens human life and health. Achieving the timely monitoring of atherosclerosis is an important measure to reduce acute cardiovascular diseases. Compared with other imaging platforms, fluorescence imaging technology has the characteristics of excellent sensitivity, high spatiotemporal resolution and real-time imaging, which is very suitable for direct visualization of molecular processes and abnormalities of atherosclerosis. Recently, researchers have strived to design a variety of fluorescent probes, from single-mode fluorescent probes to fluorescent-combined dual/multimode probes, to enrich the imaging and detection of atherosclerosis. Therefore, this review aims to provide an overview of currently investigated fluorescent probes in the context of atherosclerosis, summarize relevant published studies showing applications of different types of fluorescent probes in the early-stage and other stages to detect atherosclerosis, give effective biological targets and discuss the latest progress and some limitations. Finally, some insights are provided for the development of a new generation of more accurate and efficient fluorescent probes.

Novel ultra-sensitive and highly selective cyanine sensors based on solvent-free microwave synthesis for the detection of trace hypochlorite ions in drinking water

The adoption of chlorine in drinking water disinfection with the determination of residual chlorine in the form of hypochlorite ion (ClO-) is in widespread demand. Several sensors including colorimetric, fluorometric, and electrochemical methods are currently in use, but detection limits and ease of application remain a challenge. In this work, two new cyanine derivatives-based ClO- sensors, that were prepared by solvent-free microwave synthesis, are reported. The two sensors are highly sensitive and selective to ClO-, exhibiting a noticeable color change visible to the naked eye. Additionally, the sensors can detect ClO- without interference from other potential water pollutants, with low detection limits of 7.43 ppb and 0.917 ppb based on absorption performance. When using fluorometric methods, the sensors' detection limits are pushed down to 0.025 ppb and 0.598 ppb for sensors I and II, respectively. The sensors can be loaded with paper strips for field and domestic detection of ClO- in tap water treatment installations. Using the quartz crystal microbalance (QCM) technique, these sensors showed strong detection sensitivity to ClO-, with detection limits of 0.256 ppm and 0.09 ppm for sensors I and II, respectively. Quantum chemical studies using density functional theory (DFT) calculations, natural bond orbital (NBO) analysis, molecular electrostatic potential (MESP), and time-dependent density functional theory (TD-DFT) supported the findings. The sensing mechanism is rationalized in terms of radical cation formation upon ClO- oxidation of cyanine sensors I and II.

Dual-Emission Carbon-Dot Ratiometric Fluorescence Sensor for Morphine Recognition in Biological Samples

Herein, a novel nitr[ogen-doped carbon dot (N-CD) fluorescence sensor with a dual emission ratio is developed using the microwave-assisted synthesis of m-phenylenediamine and spermidine. As a result of the fluorescence inner filtration effect (IFE) effect between morphine (MOR) and N-CD, the blue fluorescence of N-CDs at 350 nm was reduced in the presence of MOR, whereas the fluorescence of N-CDs at 456 nm increased substantially. The results demonstrated that the approach has a tremendous potential and that the linear range of MOR detection is 0.25-25 µg/mL, with a 71.8 ng/mL detection limit. Under UV light, the blue fluorescent system is easily visible to the naked eye. More significantly, the sensor proved successful in providing satisfactory results for the speciation measurement of MOR in a variety of biological samples.

Persistent and Efficient Multimodal Imaging for Tyrosinase Based on Two-Photon Excited Fluorescent and Room-Temperature Phosphorescent Probes

Tyrosinase is crucial to regulate the metabolism of phenol derivatives, playing an important role in the biosynthesis of melanin pigments, whereas an abnormal level of tyrosinase would lead to severe diseases. It is rather necessary to develop a sensitive and selective imaging tool to assess the level of tyrosinase in vivo. We thoroughly researched the luminous mechanism of the existing TPTYR probe and provided design strategies to improve its two-photon excited fluorescence properties. The designed probes benza2-TPTYR and product benza2-TPTYR-coumarin have large two-photon absorption cross sections at the NIR spectral region (41 GM/706 nm, 71 GM/852 nm), while benza2-TPTYR-coumarin possesses easily distinguishable spectrum in the visible region and a high fluorescence efficiency (Φ_F = 0.27). What is more, novel two-photon excited multimodal imaging based on the pure organic small molecule benza1-TPTYR-coumarin (61 GM/936 nm) is proposed first, simultaneously possessing strong instantaneous fluorescent (563.79 nm) and persistent room-temperature phosphorescent emissions (767.68 nm, 0.54 ms).