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Conspectus Fluorescence imaging is a rapidly growing technique for noninvasive imaging of biological molecules and processes with high spatial and temporal resolution. For effective biological imaging, it is essential and important to develop robust fluorescent dyes, in particular, near-infrared (NIR) fluorescent dyes with favorable optical properties. Compared with the visible light emitting dyes, NIR dyes have relatively longer emission wavelengths (650-900 nm) with lower energy and are advantageous as imaging agents owing to the minimum photodamage of NIR light to biological samples, deep penetration into tissues, and low interference from autofluorescence of biomolecules. Although great efforts have been devoted to engineer NIR fluorophores, it is still very challenging to regulate their photophysical properties as they often lack optically tunable mechanisms, and this shortcoming considerably restricts the realization of their full potential. Consequently, the rational design of small-molecule optically tunable NIR fluorophores is of high priority and great value. In general, two key characteristics are indispensable for designing excellent optically tunable NIR fluorescent dyes. First, NIR fluorescent dyes should display the maximal absorption and emission located in the NIR region and also have the prominent properties including excellent fluorescence quantum yields, large Stokes shifts, good chemical stability and photostability, low cytotoxicity, and desirable compatibility with biological systems. Second, in principle, functional NIR dyes should also possess optically tunable groups, which can be easily modified to afford responsive sites for the targets of interest. With these considerations in mind, in this Account, we described a unique "integration" strategy for judicious design of the optically tunable NIR fluorophores, which are an intuitive combination of the traditional NIR dyes and the optically tunable mechanisms in the visible light emissive dyes. Thus, the versatile strategy may allow not only retention of the NIR emission properties of NIR dyes but also inheritance of the optically tunable mechanisms from the visible light emissive dyes. By the unique integration strategy, a built-in optically tunable group is strategically installed into the traditional NIR fluorescent dyes to directly tune their optical properties. Herein, we present a concise review of the rational design strategy and biological applications of small-molecule optically tunable NIR fluorescent dyes via the unique integration strategy, and we focused mainly on our work and some representative examples from other groups based on our NIR platforms. This Account includes the detailed integration strategy of each class of the NIR fluorescent dyes, the development of their derivatives, and their imaging applications in living systems. [ABSTRACT FROM AUTHOR]

Acidic pH is a critical physiological factor for controlling the activities and functions of lysosome. Herein, we report a novel dual site-controlled and lysosome-targeted intramolecular charge transfer-photoinduced electron transfer-Fluorescence resonance energy transfer (ICT-PET-FRET) fluorescent probe (CN-pH), which was essentially the combination of a turn-on pH probe (CN-1) and a turn-off pH probe (CN-2) by a nonconjugated linker. Coumarin and naphthalimide fluorophores were selected as donor and acceptor to construct the FRET platform. Hydroxyl group and morpholine were simultaneously employed as the two pH sensing sites and controlled the fluorescence of coumarin and naphthalimide units by ICT and PET, respectively. The sensing mechanism of CN-pH to pH was essentially an integration of ICT, PET, and FRET processes. Meanwhile, the morpholine also can serve as a lysosome-targeted group. By combining the two data analysis approaches of the ratios of the two emission intensities (R) and the reverse ratio R-' (R' = 1/R), the fluorescent ratio of CN-pH can show proportional relationship to pH values in a very broad range from pH 4.0 to 8.0 with high sensitivity. The probe has been successfully applied for the fluorescence imaging of the lysosomal pH values, as well as ratiometrically visualizing chloroquine-stimulated changes of intracellular pH in living cells. These features demonstrate that the probe can afford practical application in biological systems. [ABSTRACT FROM AUTHOR]

Correction for 'Fluorescence imaging of cellular GSH to reveal the hindering influence of rutin on ferroptosis' by Abdul Hadi Mehmood et al., New J. Chem., 2024, 48, 14175–14181, https://doi.org/10.1039/D4NJ00397G. [ABSTRACT FROM AUTHOR]

The New Journal of Chemistry, published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique, contains a variety of articles on topics such as photocatalysts, Li-ion batteries, biofilm removal, and synthesis of different compounds. The document is a contents list for the journal's October 14, 2024 issue. The first paper discusses the synthesis and anti-cancer activity of acetals of arjunolic acid, while the second paper explores the hybridization of magnetic MOF composites with 3D terminal carboxyl hyperbranched polymers for dye wastewater treatment. The third entry is a correction to a previous article on fluorescence imaging of cellular GSH and the hindering influence of rutin on ferroptosis. [Extracted from the article]

The document is a contents list for the New Journal of Chemistry, a journal focused on new directions in chemistry. It includes various articles and papers on topics such as lithium-ion batteries, organic synthesis, photocatalysts, and nanocatalytic systems. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. [Extracted from the article]

Ferroptotic cell death is significantly regulated by glutathione (GSH), an important antioxidant. This work describes the development of a novel, small fluorescent probe capable of detecting GSH levels and providing an understanding of the inhibitory effect of rutin, a naturally occurring flavonoid, during ferroptosis. The probe N-GSH exhibited outstanding sensitivity and selectivity towards GSH, as witnessed by the significant increase in fluorescence observed after GSH binding. Additionally, the probe N-GSH determined the possible inhibitory effect of rutin and the role of GSH in ferroptosis. Using fluorescence imaging, the probe N-GSH revealed that GSH levels reduced significantly during ferroptosis induction, demonstrating its vital role in the process. Furthermore, by significantly preserving GSH levels, rutin treatment prevented ferroptosis. Moreover, in comparison to additional typical ferroptosis inhibitors, such as dihydrolipoic acid (DHLA) and vitamin E (VE), it was hypothesized that rutin's inhibitory effect on ferroptosis was achieved through the synergistic effect of its antioxidant and chelate properties on Fe(II) ions. [ABSTRACT FROM AUTHOR]

Enhancing the assessment of compressive strength and the efficiency of rebound hammers in non-destructive testing for high-strength concrete is an urgent issue in construction engineering. This study involved C50 to C90 high-strength concrete specimens, utilizing rebound hammers with nominal energies of 4.5 J and 5.5 J, along with a compression machine. A regression analysis was performed on the compressive strength and rebound values, resulting in linear, polynomial, power, exponential, and logarithmic equations for two different types of rebound hammers. Additionally, the precision of rebound hammers with different nominal energies and the representativeness of various rebound representative values in the measurement area were investigated. The experimental results indicate that the precision of the regionally representative strength curve in Xinjiang meets national specifications. The 4.5 J nominal energy rebound hammer exhibited a higher testing accuracy. When reducing the high-strength concrete measurement area's rebound representative values from 16 to 14, 12, and 10, the coefficients of variation for the different rebound representative values were mostly below 10%. Within high-strength concrete structures, the strength curve formula derived from rebound representative value 16 is equally applicable to 14, 12, and 10. In practical engineering applications, prioritizing 10 ensures testing accuracy while reducing on-site testing efforts. The outcomes of this experiment establish a foundation for the development and promotion of rebound method-testing technology for high-strength concrete in Xinjiang. [ABSTRACT FROM AUTHOR]

Polysiloxane is widely used in biomedical applications because of its good biocompatibility and excellent micro and nano-scale processability. Using PubMed and Citex's data analysis platform, this paper examines polysiloxane research and compares its development history from 2002-01 to 2021-12. Research hotspots, keyword analysis, and the number of papers published on polysiloxane in biomedicine are used in this study to analyze and discuss the current status of polysiloxane research in biomedicine. Over the last twenty years, there has been a significant surge in the number of publications related to the use of polysiloxane in biomedicine. This trend highlights the growing intersection and collaboration between the fields of polymeric material science and biomedical disciplines. Therefore, statistics about the number of papers on polysiloxane and the frequency of hot words are valuable resources for biomedical research and development. [ABSTRACT FROM AUTHOR]

Superoxide anion (O2•−) is an important reactive oxygen species (ROS), and plays critical roles in biological systems. ER stress has close relation with many metabolic diseases, and could lead to the abnormal production of ROS including O2•−. Herein, we present an ER-targeting probe (ER-Tf) for the detection of O2•− in living cells. The probe ER-Tf used triflate as the response site for O2•−, and employed p-methylbenzenesulfonamide as ER-targeting moiety. In response to O2•−, the triflate of the probe ER-Tf converted to hydroxyl group, providing strong blue emission under the excitation of ultraviolet light. The probe ER-Tf exhibited high sensitivity and selectivity to O2•−. Bioimaging experiments showed that the probe ER-Tf can be applied to detect O2•− at ER, and also demonstrated that rotenone could increase the generation of O2•− in living cells, while the O2•− level at ER showed no remarkable change during ferroptosis. [ABSTRACT FROM AUTHOR]

Carboxylesterase (CEs), mainly localized in endoplasmic reticulum (ER), are responsible for hydrolyzing compounds containing various ester bonds. They have been closely associated with drug metabolism and cellular homeostasis. Although some CE fluorescent probes have been developed, there are still a lack of probes that could target to the ER. Here, we developed a novel fluorescent probe CR with a specific ER anchor for monitoring CEs. In CR, p‐toluenesulfonamide was chosen for precise ER targeting. A simple acetyl moiety was used as the CE response site and fluorescence modulation unit. During the spectral tests, CR displayed a fast response speed (within 10 s) towards CEs. In addition, it showed high sensitivity [limit of detection (LOD) = 5.1 × 10−3 U/ml] and high selectivity with CEs. In biological imaging, probe CR could especially locate in the ER in HepG2 cells. After cells were treated with orilistat, CR succeeded in monitoring the changes in the CEs. Importantly, CR also had the ability to trace the changes in CEs in a tunicamycin‐induced ER stress model. Therefore, probe CR could be a powerful molecular tool for further investigating the functions of CEs in the ER. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO2) plays critical biological roles in living systems, and participates in a series of physiological and pathological processes. Aspartate aminotransferase 2 (AAT-2) catalyzes L -cysteine to produce endogenous SO2, which is mainly expressed in the mitochondria of cells. Herein, we present a new mitochondria-targeting and ratiometric fluorescent probe (MNP) for the detection of SO2 in living cells. The probe MNP employed a positively charged benzopyrylium moiety as the response site for SO2, and displayed a selective ratiometric response to SO2 on the basis of a FRET mechanism. Biological experiments demonstrated that the probe MNP was mainly distributed in mitochondria and could be used for the imaging of SO2 in living cells. [ABSTRACT FROM AUTHOR]

Propanedioyl dihydrazide (PDH), traditionally believed to be non-fluorescent, was first discovered to emit substantial fluorescence in both the solid state and solvents. Then, significantly, a novel strategy is provided: fluorescent non-aromatic small molecules with rigid molecular structures could be constructed by forming hydrogen bonds. [ABSTRACT FROM AUTHOR]

Unconventional fluorescent materials have attracted intense and continuous attention due to the facile processability, excellent biocompatibility, and high availability. However, for the lack of suitable unconventional fluorescent platform, unconventional luminophore‐based fluorescent probes have not been applied in the biological field, especially in the detection of bioactive molecules. In this work, unconventional red fluorescence is observed from a series of organoalkoxysilanes for the first time. Particularly, the unique fluorescence derived from smart Si–O bridged structures prompt the fluorescent probe design strategy. The strategy involves applying the Si–O bridge to provide desirable red unconventional fluorescence, and ratiometric detection of endogenous nitric oxide in lysosomes and in vivo. It is expected that this novel strategy will expand the applications of unconventional fluorescence to the bioimaging field, and further provide valid approach for the future evolution of unconventional fluorescent probes. [ABSTRACT FROM AUTHOR]

Currently, fluorescent sensors for the detection of H2O in D2O are still quite rare. Herein, we present a dual-site controlled fluorescent sensor (CF-D2O) for the detection of H2O in D2O. As the H2O content in D2O decreases (namely, the purity of D2O increases), sensor CF-D2O provides two turn-on fluorescence signals. The response mechanism of sensor CF-D2O to H2O is based on the deprotonation of the two hydroxyl groups, as well as the FRET process between coumarin and xanthene units. [ABSTRACT FROM AUTHOR]

Herein, we present a dual-site ratiometric fluorescent probe based on the ICT-PET-FRET mechanism for the detection of pH in the ER. The probe showed a highly sensitive response to pH in the range of 5.0–7.2, and could be applied for the quantitative measurement of the pH values in the ER during ER stress and dexamethanose-induced stimulation. [ABSTRACT FROM AUTHOR]

In this work, a unique dual-site controlled fluorescent probe was presented for the sensitive and concurrent detection of pH in the cytoplasm and lysosomes. With the probe, the simultaneous down-regulation of pH in the lysosomes and cytoplasm during autophagy has been successfully revealed for the first time. [ABSTRACT FROM AUTHOR]

Cell polarity is one of the important parameters of the biological microenvironment and controls the synthesis of functional proteins. As one of the key links in protein synthesis, the endoplasmic reticulum is highly sensitive to the cellular environment and closely related to cell polarity. Herein, we present an ER-targeting fluorescent probe (NSp) for the detection of cell polarity. The probe NSp used naphthalimide as a fluorescent platform and the p-toluenesulfonamide group as an ER targeting group. The red shift of the probe NSp in different solvents can reach 45 nm, and the displacement value in the system of dioxane and water can reach 50 nm. In addition, biological experiments show that the probe NSp shows a difference in the fluorescence intensity of normal cells and cancer cells, and the differentiation between normal cells and cancer cells is successful under conditions of endoplasmic reticulum stress. Besides, the probe can be used to distinguish between normal and cancerous tissues. [ABSTRACT FROM AUTHOR]

Formaldehyde (FA), a well-known carbonyl species, plays a crucial role in physiological function and is produced endogenously via enzymatic pathways. However, an abnormal concentration of FA is closely related with various types of diseases, including Alzheimer's disease, cancer and diabetes. Thus, it is significant to real-time visualize the changes in FA in organisms. In this study, we engineered a unique two-photon probe for sensing FA based on a coumarin derivative as a two-photon reporter and a homoallylamino group as the responsive site. In the presence of FA, the probe showed good selectivity, a low detection limit and high stability. Significantly, its successful application in living cells and zebrafish showed that this probe has the ability to sense FA with the desirable two-photon mode. Moreover, with its feature of high resolution, the three-dimensional imaging of living tissues exhibited remarkable fluorescence signal changes with/without the treatment of FA with this probe in the two-photon mode. Therefore, this probe is a powerful molecular tool for sensing FA in living systems. [ABSTRACT FROM AUTHOR]

SO2 has been recently identified as an essential gas messenger followed by NO, CO and H2S. However, abnormal concentrations of SO2 in our bodies can cause many diseases. Thus, the real-time monitoring of SO2 to well define the generation, physiological and pathological functions of SO2 is urgently needed. In this work, we developed a novel SO2 fluorescent probe on the basis of the conjugation of semi-cyanine and coumarin derivate dyes with superior features, such as near-infrared (NIR) and two-photon dual-mode monitoring, a large Stokes shift (175 nm), ultrafast response towards SO2 (within 10 s), high selectivity and photostability. Furthermore, this probe could sense SO2 by dual colorimetric and fluorescence means. In biological imaging, the probe was able to trace exogenous and endogenous SO2 in living cells, mitochondria, E. coli, zebrafish and mice under an NIR and two-photon dual-mode. These results demonstrated that the probe has strong potential for studying the physiological and pathological functions of SO2in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Developing a reliable method to detect Na2S2O4 in real time is of great importance for the in-depth study of its toxicity to humans and to allow it to be safely handled. Currently, research on the fluorescence imaging of Na2S2O4 is very scarce. Herein, we present azo-based turn-on fluorescent probes with a high signal-to-noise ratio (emission enhancement ＞100-fold) for the visualization of Na2S2O4 in living cells. [ABSTRACT FROM AUTHOR]

Mitochondria and nucleus play crucial roles during cell apoptosis process. In this work, a unique fluorescent probe capable of reversible migration between mitochondria and nucleus, as well as detection of cell viability in a dual‐color mode is presented. The dual‐color probe targets mitochondria in healthy cells, to form aggregates with deep‐red emission. It migrates into nucleus and binds to DNA to form monomers with green fluorescence during apoptosis. Interestingly, the migration is reversible dependent on cell viability, which enables the dynamic visualization of apoptosis process. With the probe, mitochondria and nucleus can be visualized in dual colors during apoptosis, and the cell viability could be monitored by the emission color and localization of the probe. Visualizing cell viability: A fluorescent probe capable of reversible migration between mitochondria and nucleus dependent on cell viability and labelling the two organelles in dual colors has been developed. With the probe, mitochondria and nucleus can be visualized in dual emission channels, and cell viability could be evaluated by intracellular emission color and probe localization. [ABSTRACT FROM AUTHOR]