A newly nitrobenzoxadiazole (NBD)-fused reversible fluorescence probe for pH monitoring and application in bioimaging

Rapid and ultra-sensitive trace water determination in organic solvents utilizing nitrobenzoxadiazole (NBD)-based fluorescent sensing system

The presence of minute quantities of water in organic solvents can affect the progress of many reactions and cause unnecessary losses and even safety accidents in the chemical industry, especially in the productions process of organic fine chemicals. Therefore, it is necessary to carry out high-performance strategies for trace water detections in commonly used organic solvents. In this work, a fluorescent sensing system based on competitive binding of protons has been developed, demonstrating remarkable responses by UV-vis absorption and fluorescence two-modes toward a trace amount of water in organic solvents including 1,4-dioxane (Diox), tetrahydrofuran (THF), acetonitrile (MeCN), acetone (ACE), dimethylsulfoxide (DMSO) and mixed organic solvents (THF: MeCN=1: 1). The key component of the sensing system is a newly designed fluorophore NBD-PMA, which can be deprotonated to form a dynamic non-luminescent adduct, namely NBD-PMA-F, by an organic fluoride salt tetrabutylammonium fluoride (TBAF). NBD-PMA-F can be reprotonated via using trace water, exhibiting fluorescence turn on of the system. The as-prepared sensing system shows superior sensitivity, low detection limits (v/v, 0.0007 %), quick response speed (≤1.2 s) and good reversibility. Moreover, naked-eye visual rapid detection has also been successfully realized at ambient temperature, which demonstrated their practical applications value for trace water determinations.

Application of Intelligent Response Fluorescent Probe in Breast Cancer

As one of the leading cancers threatening women's lives and health, breast cancer is challenging to treat and often irreversible in advanced cases, highlighting the critical importance of early detection and intervention. In recent years, fluorescent probe technology, a revolutionary in vivo imaging tool, has gained attention in medical research for its ability to improve tumor visualization significantly. This review focuses on recent advances in intelligent, responsive fluorescent probes, particularly in the field of breast cancer, which are divided into five categories, near-infrared responsive, fluorescein-labeled, pH-responsive, redox-dependent, and enzyme-triggered fluorescent probes, each of which has a different value for application based on its unique biological response mechanism. In addition, this review also covers the strategy of combining fluorescent probes with various anti-tumor drugs, aiming to reveal the possibility of synergistic effects between the two in breast cancer treatment and provide a solid theoretical platform for the clinical translation of fluorescent probe technology, which is expected to promote the expansion of cancer treatment technology.

Fluorescent chemosensors facilitate the visualization of plant health and their living environment in sustainable agriculture

Globally, 91% of plant production encounters diverse environmental stresses that adversely affect their growth, leading to severe yield losses of 50-60%. In this case, monitoring the connection between the environment and plant health can balance population demands with environmental protection and resource distribution. Fluorescent chemosensors have shown great progress in monitoring the health and environment of plants due to their high sensitivity and biocompatibility. However, to date, no comprehensive analysis and systematic summary of fluorescent chemosensors used in monitoring the correlation between plant health and their environment have been reported. Thus, herein, we summarize the current fluorescent chemosensors ranging from their design strategies to applications in monitoring plant-environment interaction processes. First, we highlight the types of fluorescent chemosensors with design strategies to resolve the bottlenecks encountered in monitoring the health and living environment of plants. In addition, the applications of fluorescent small-molecule, nano and supramolecular chemosensors in the visualization of the health and living environment of plants are discussed. Finally, the major challenges and perspectives in this field are presented. This work will provide guidance for the design of efficient fluorescent chemosensors to monitor plant health, and then promote sustainable agricultural development.

Response strategies and biological applications of organic fluorescent thermometry: cell- and mitochondrion-level detection

Temperature homeostasis is critical for cells to perform their physiological functions. Among the diverse methods for temperature detection, fluorescent temperature probes stand out as a proven and effective tool, especially for monitoring temperature in cells and suborganelles, with a specific emphasis on mitochondria. The utilization of these probes provides a new opportunity to enhance our understanding of the mechanisms and interconnections underlying various physiological activities related to temperature homeostasis. However, the complexity and variability of cells and suborganelles necessitate fluorescent temperature probes with high resolution and sensitivity. To meet the demanding requirements for intracellular/subcellular temperature detection, several strategies have been developed, offering a range of options to address this challenge. This review examines four fundamental temperature-response strategies employed by small molecule and polymer probes, including intramolecular rotation, polarity sensitivity, Förster resonance energy transfer, and structural changes. The primary emphasis was placed on elucidating molecular design and biological applications specific to each type of probe. Furthermore, this review provides an insightful discussion on factors that may affect fluorescent thermometry, providing valuable perspectives for future development in the field. Finally, the review concludes by presenting cutting-edge response strategies and research insights for mitigating biases in temperature sensing.

Lysosomes-targeting near-infrared fluorescent probe for the detection of pH in living cells

A new near-infrared fluorescent probe Qcy-OH with a turn-on mechanism based on a acceptor-donor-acceptor (ADA) π-electron system that can undergo an internal charge transfer to form new fluorochromes was developed for monitoring pH fluctuations in biological systems. With the pH value increases, Qcy-OH exhibited a strong pH-sensitive response from 1.1 to 9.0 (pKa = 4.41) and a good linear response from pH 3.0 to 5.5 in aqueous solution and in living cells. In addition, based on the phenolic and ketonic structure interconversions of the fluorescent backbone, Qcy-OH showed rapidly and reversibly response to pH with high selectivity. Because the introduce of two benzothiazolium units in the backbone of the probe as the electron-withdrawing group to enhance the selectivity for intracellular lysosomes, the probe had been applied successfully for tracking lysosomal pH changes and the fluorescence changes showed a good linear enhancement from pH 3.0 to 7.4 in living cells. We believe that this sulfur-driving lysosomes-targeting ability of the probe affords a guarantee for achieving long-term monitoring of lysosomal pH biology by the elimination of harmful protonating effects of the probe.

Nanoparticulate Photoluminescent Probes for Bioimaging: Small Molecules and Polymers

Recent interest in research on photoluminescent molecules due to their unique properties has played an important role in advancing the bioimaging field. In particular, small molecules and organic dots as probes have great potential for the achievement of bioimaging because of their desirable properties. In this review, we provide an introduction of probes consisting of fluorescent small molecules and polymers that emit light across the ultraviolet and near-infrared wavelength ranges, along with a brief summary of the most recent techniques for bioimaging. Since photoluminescence probes emitting light in different ranges have different goals and targets, their respective strategies also differ. Diverse and novel strategies using photoluminescence probes against targets have gradually been introduced in the related literature. Among recent papers (published within the last 5 years) on the topic, we here concentrate on the photophysical properties and strategies for the design of molecular probes, with key examples of in vivo photoluminescence research for practical applications. More in-depth studies on these probes will provide key insights into how to control the molecular structure and size/shape of organic probes for expanded bioimaging research and applications.

A benzimidazole-based ratiometric fluorescent probe for the accurate and rapid monitoring of lysosomal pH in cell autophagy and anticounterfeiting

The lysosomal targeted ratiometric fluorescent BD probe reveals excellent application performance in the fields of selective monitoring of the lysosome pH of living cells, real-time dynamic monitoring of autophagy, and document anti-counterfeiting.

A reaction-based colorimetric and ratiometric chemosensor for imaging identification of HClO in live cells, mung bean sprouts, and paper strips

Hypochlorous acid (HClO) as well as its ionic form (ClO^-), representative of reactive oxygen species (ROS), are essential players in all sorts of biological processes. The abnormal level of each can lead to the onset of various diseases. Besides, Sodium hypochlorite, a commonly-used bleaching agent in our daily lives, could also result in breathing and skin problems when overexposed. Therefore, developing a molecular chemosensor for sensing HClO is of biological and environmental importance. Though many such chemosensors have been reported, new HClO chemosensors with different sensing performances may still come in handy in certain situations. In this work, we have developed a new coumarin-based chemosensor, CM-hbt, for realizing both ratiometric and colorimetric imaging detection of HClO in live cells. Notably, we further explored its application in sensing HClO in plant mung beans as well as fabricated an easy-to-use paper strip apparatus for facilitating its quick detection, which is seldomly seen in other HClO chemosensors. All the analysis results confirmed the high sensitivity and selectivity of this novel chemosensor. DFT calculations were used to decipher the underlying sensing mechanism of CM-hbt. Overall, this work presents a novel chemosensor, CM-hbt, as a colorimetric and ratiometric chemosensor for realizing imaging detection of HClO in a variety of different model systems, which highlights its broad spectrum of application potentials.