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Functional fluorophores represent an emerging research field, distinguished by their diverse applications, especially in sensing and cellular imaging. After the discovery of quinine sulfate and subsequent elucidation of the fluorescence mechanism by Sir George Stokes, research in the field of fluorescence gained momentum. Over the past few decades, advancements in sophisticated instruments, including super-resolution microscopy, have further promoted cellular imaging using traditional fluorophores. These advancements include deciphering sensing mechanisms via photochemical reactions and scrutinizing the applications of fluorescent probes that specifically target organelles. This approach elucidates molecular interactions with biomolecules. Despite the abundance of literature illustrating different classes of probe development, a concise summary of newly developed fluorophores remains inadequate. In this review, we systematically summarize the chronological discovery of traditional fluorophores along with new fluorophores. We briefly discuss traditional fluorophores ranging from visible to near-infrared (NIR) in the context of cellular imaging and in vivo imaging. Furthermore, we explore ten new core fluorophores developed between 2007 and 2022, which exhibit advanced optical properties, providing new insights into bioimaging. We illustrate the utilization of new fluorophores in cellular imaging of biomolecules, such as reactive oxygen species (ROS), reactive nitrogen species (RNS), and proteins and microenvironments, especially pH and viscosity. Few of the fluorescent probes provided new insights into disease progression. Furthermore, we speculate on the potential prospects and significant challenges of existing fluorophores and their potential biomedical research applications. By addressing these aspects, we intend to illuminate the compelling advancements in fluorescent probe development and their potential influence across various fields. [ABSTRACT FROM AUTHOR]

High altitude (HA) environments contain low levels of oxygen, which often cause nonspecific gastrointestinal (GI) disorders associated with acute mountain sickness (AMS). This study is conducted to investigate the alternation of microbial population and the physiological indices after being exposed to HA. Fecal and blood samples were collected from twelve army personnel in base-level environments in (Delhi, India) after acclimatization for seven days at 3505 m HA (Lah, India). Different bacterial groups, oxygen saturation level (SPO2), serum hemoglobin (Hb), hematocrit (HCT), blood urea, creatinine and microbial enzymes such as the α-amylase, proteinase, alkaline phosphatase and β-glucuronidase levels were all measured. It was observed that the total aerobic bacteria decreased significantly and the anaerobic and facultative anaerobic increased gradually in the intestines. Strict anaerobes including Bacteroidetes sp., Bifidobacterium sp., Lactobacillus sp. as well as pathogenic bacteria such as the Salmonella sp. exhibited positive growth. Various physiological parameters including serum hemoglobin, hematocrit, and urea-creatinine were also significantly changed. The microbial enzyme-activity also increased at HA. This confirms that the exposure to HA can change the intestinal microbial population affecting the microbial enzyme production possibly causing GI dysfunctions as a result of the decreased availability of oxygen. [ABSTRACT FROM AUTHOR]

Drug toxicity is a long-standing concern of modern medicine. A typical anti-pain/fever drug paracetamol often causes hepatotoxicity due to peroxynitrite ONOO−. Conventional blood tests fail to offer real-time unambiguous visualization of such hepatotoxicity in vivo. Here we report a luminescent approach to evaluate acute hepatotoxicity in vivo by chromophore-conjugated upconversion nanoparticles. Upon injection, these nanoprobes mainly accumulate in the liver and the luminescence of nanoparticles remains suppressed owing to energy transfer to the chromophore. ONOO− can readily bleach the chromophore and thus recover the luminescence, the presence of ONOO− in the liver leads to fast restoring of the near-infrared emission. Taking advantages of the high tissue-penetration capability of near-infrared excitation/emission, these nanoprobes achieve real-time monitoring of hepatotoxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs. [ABSTRACT FROM AUTHOR]

Drug toxicity is a long-standing concern of modern medicine. A typical anti-pain/fever drug paracetamol often causes hepatotoxicity due to peroxynitrite ONOO−. Conventional blood tests fail to offer real-time unambiguous visualization of such hepatotoxicity in vivo. Here we report a luminescent approach to evaluate acute hepatotoxicity in vivo by chromophore-conjugated upconversion nanoparticles. Upon injection, these nanoprobes mainly accumulate in the liver and the luminescence of nanoparticles remains suppressed owing to energy transfer to the chromophore. ONOO− can readily bleach the chromophore and thus recover the luminescence, the presence of ONOO− in the liver leads to fast restoring of the near-infrared emission. Taking advantages of the high tissue-penetration capability of near-infrared excitation/emission, these nanoprobes achieve real-time monitoring of hepatotoxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs. [ABSTRACT FROM AUTHOR]

Investigation of the genetic functions in complex biological systems is a challenging step in recent year. Hence, several valuable and interesting research projects have been developed with novel ideas to find out the unknown functions of genes or proteins. To validate the applicability of their novel ideas, various approaches are built up. To date, the most promising and commonly used approach for discovering the target proteins from biological system using small molecule is well known a forward chemical genetics which is considered to be more convenient than the classical genetics. Although, the forward chemical genetics consists of the three basic components, the target identification is the most challenging step to chemical biology researchers. Hence, the diverse target identification methods have been developed and adopted to disclose the small molecule bound protein. Herein, in this review, we briefly described the first two parts chemical toolbox and screening, and then the target identifications in forward chemical genetics are thoroughly described along with the illustrative real example case study. In the tabular form, the different biological active small molecules which are the successful examples of target identifications are accounted in this research review. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel quinoline based multifunctional viologen compound. • Crystal structure of both the neutral and dication have been elucidated. • Photophysical properties with large Stokes shifts and pH dependence. • Reversible redox properties. • Application in sensing of ct-DNA by selective quenching of fluorescence, over ATP and AMP. • Application in bioimaging by intracellular colocalization studies in HeLa cells. Developing new multifunctional organic materials is one of the current themes of research in organic materials chemistry. The class of N,N' -dialkylated bis-pyridinium compounds, namely, the viologens have been proven to offer such multifunctional materials. Herein, syntheses and crystal structure elucidation of trans -1,2-bis(4-quinolinyl)ethylene (BQE) and analogous N,N -dimethylated trans -1,2-bis(4′-quinolinium)ethylene (M 2 BQE) are discussed with their multifaceted materials properties. Two different crystal structures with significantly different molecular structures, namely, BQE and BQE⋅2H 2 O were obtained by tuning the solvent of crystallization. M 2 BQE showed a bathochromic shift both in its absorption by ∼ 3300 cm−1 and in emission by ∼2900 cm−1 in compared to BQE , which is the effect of quaternization. Large Stokes shifts were observed for both the BQE (∼8500 cm−1) and M 2 BQE (∼8050 cm−1). Both compounds showed two-step reduction events in cyclic voltammetry, of which the first steps were reversible. The pH dependent absorption and emission properties of BQE have been explored which revealed the stronger effect by methylation than protonation. M 2 BQE exhibited selective binding to ct-DNA, as confirmed by selective quenching of emission intensity, over AMP and ATP. Furthermore, both the BQE and M 2 BQE displayed very intriguing features in bioimaging by intracellular co-localization in HeLa cells. While BQE is predominantly localizes in lysosomes over mitochondria, M 2 BQE dication, on the other hand, explicitly localizes in mitochondria. [ABSTRACT FROM AUTHOR]

This review explains various strategies for developing fluorescent probes to detect reactive carbonyl species (RCS). There are several mono and diacarbonyls among 30 varieties of reactive carbonyl species (RCSs) so far discovered, which play pivotal roles in pathological processes such as cancer, neurodegenerative diseases, cardiovascular disease, renal failure, and diabetes mellitus. These RCSs play essential roles in maintaining ion channel regulation, cellular signaling pathways, and metabolisms. Among RCSs, carbon monoxide (CO) is also utilized for its cardioprotective, anti‐inflammatory, and anti‐apoptotic effects. Fluorescence‐based non‐invasive optical tools have come out as one of the promising methods for analyzing the concentrations and co‐localizations of these small metabolites. There has been a tremendous eruption in developing fluorescent probes for selective detection of specific RCSs within cellular and aqueous environments due to their high sensitivity, high spatial and temporal resolution of fluorescence imaging. Fluorescence‐based sensing mechanisms such as intramolecular charge transfer (ICT), photoinduced electron transfer (PeT), excited‐state intramolecular proton transfer (ESIPT), and fluorescence resonance energy transfer (FRET) are described. In particular, probes for dicarbonyls such as methylglyoxal (MGO), malondialdehyde (MDA), along with monocarbonyls that include formaldehyde (FA), carbon monoxide (CO) and phosgene are discussed. One of the most exciting advances in this review is the summary of fluorescent probes of dicarbonyl compounds. [ABSTRACT FROM AUTHOR]

SERS nanotags have been prepared to accomplish the multiplex detection of cancer cells. Herein we evaluated the adequacy of lipoic acid-containing cyanine derivatives (Cy3LAand Cy5LA) to function as multiplex partners with a triphenylmethine Raman reporter (B2LA) under a single excitation wavelength. SERS experiments enabled the multiplex recognition of two different cancer cells with antibody-conjugated nanotags that were derivatized with optimized cyanine and triphenylmethine reporters. [ABSTRACT FROM AUTHOR]

Ferroptosis is a recently identified form of regulated cell death characterized by iron accumulation and lipid peroxidation. Numerous functions for ferroptosis have been identified in physiological as well as pathological processes, most notably in the treatment of cancer. The intricate balance of redox homeostasis is profoundly altered during ferroptosis, leading to alteration in cellular microenvironment. One such microenvironment is viscosity among others such as pH, polarity, and temperature. Therefore, understanding the dynamics of ferroptosis associated viscosity levels within organelles is crucial. To date, there are a very few reviews that detects ferroptosis assessing reactive species. In this review, we have summarized organelle's specific fluorescent probes that detects dynamics of microviscosity during ferroptosis. Also, we offer the readers an insight of their design strategy, photophysics and associated bioimaging concluding with the future perspective and challenges in the related field. [ABSTRACT FROM AUTHOR]

The intracellular pH (pHi) in organelles, including mitochondria, endoplasmic reticulum, lysosomes, and nuclei, differs from the cytoplasmic pH, and thus maintaining the pH of these organelles is crucial for cellular homeostasis. Alterations in the intracellular pH (ΔpHi) in organelles lead to the disruption of cell proliferation, ion transportation, cellular homeostasis, and even cell death. Hence, accurately mapping the pH of organelles is crucial. Accordingly, the development of fluorescence imaging probes for targeting specific organelles and monitoring their dynamics at the molecular level has become the forefront of research in the last three decades. Among them, ratiometric fluorescent probes minimize the interference from the excitation wavelength of light, auto-fluorescence from probe concentration, environmental fluctuations, and instrument sensitivity through self-correction compared to monochromatic fluorescent probes, which are known as turn-on/off fluorescent probes. Small-molecular ratiometric fluorescent probes for detecting ΔpHi are challenging yet demanding. To date, sixty-two ratiometric pH probes have been reported for monitoring internal pH alterations in cellular organelles. However, a critical review on organelle-specific ratiometric probes for pH mapping is still lacking. Thus, in the present review, we report the most recent advances in ratiometric pH probes and the previous data on the role of mapping the ΔpHi of cellular organelles. The development strategy, including ratiometric fluorescence with one reference signal (RFRS) and ratiometric fluorescence with two reversible signals (RFRvS), is systematically illustrated. Finally, we emphasize the major challenges in developing ratiometric probes that merit further research in the future. [ABSTRACT FROM AUTHOR]

Abstract: Organelle‐targeted photosensitizers (PSs) having luminescence properties are potential theranostic agents for simultaneous luminescence imaging and photodynamic therapy. Herein, we report a water‐soluble luminescent cyclometalated IrIII complex, Ir‐Bp‐Ly, as a lysosome‐targeted theranostic probe. Ir‐Bp‐Ly exhibits exceptional photophysical properties, with good triplet‐state quantum yield (0.90), singlet oxygen generation quantum yield (0.71 at pH 4), and long lifetime (1.47 μs). Interestingly, Ir‐Bp‐Ly localizes mostly in lysosomes due to the presence of morpholine units, suggesting its potential use as a lyso‐tracker. Ir‐Bp‐Ly displays a notable PDT effect in C6 glioma cells, efficiently generating reactive oxygen species owing to close proximity between the energy levels of its triplet state and those of molecular oxygen (3O2). The mechanism of cell death has been studied through caspase‐3/7 and flow cytometry analyses, which clearly established the apoptotic pathway. [ABSTRACT FROM AUTHOR]

Mitochondria are the powerhouse of the cell and function at pH ∼8.0. Dysfunctions of mitochondria, includes mitochondrial damage, leading to pH alteration. Hence, researchers aim to develop efficient pH probes for tracking mitochondrial pH dynamics. Herein, we developed a PET‐based fluorescent probe for pH monitoring during mitochondrial dysfunctions. Three derivatives were synthesized with a variable spacer's length in pentacyclic pyridinium fluorophores (PM‐C2, PM‐C3, and PM‐C6). An efficient electron transfers from the receptor (tertiary amine) was observed in the case of PM‐C2 compared to the other two derivatives. This PET process was inhibited when tertiary amine was protonated in acidic pH. However, PM‐C3 showed minimal fluorescence intensity at similar conditions and almost negligible change in case of PM‐C6, suggesting poor PET process for both the derivatives. Furthermore, DFT/TD‐DFT quantum chemical calculation well supported this optical phenomena and PET process. Biocompatible, photostable, and mitochondria‐specific PM‐C2 could monitor pH dynamics during mitochondrial damage which were engulfed by lysosome, also known as mitophagy. This mitophagy process were induced by rapamycin and starvation, which can be monitored by turn‐on fluorescence enhancement. This process was further validated by tracking Parkin‐protein translocation from cytoplasm to damaged mitochondria using our developed probe. [ABSTRACT FROM AUTHOR]

Esterases enzymes regulate the body's homeostasis by catalyzing the hydrolysis of various esters. These are also involved in protein metabolism, detoxification, and signal transmission. Most importantly, esterase plays a significant role in cell viability and cytotoxicity assays. Hence, developing an efficient chemical probe is essential for monitoring the esterase activity. Several fluorescent probes for esterase have also been reported targeting cytosol and lysosomes. However, the ability to create efficient probes is constrained due to a lack of understanding of the esterase's active site for hydrolyzing the substrate. In addition, the fluorescent turn‐on may limit efficient monitoring. Herein, we have developed a unique fluorescent probe, PM‐OAc, to monitor mitochondrial esterase enzyme activity ratiometrically. This probe exhibited a bathochromic wavelength shift with esterase enzyme in alkaline pH (pH∼8.0) due to an intramolecular charge transfer (ICT) process. The phenomenon is well supported by TD‐DFT calculation. Moreover, the substrate (PM‐OAc) binding at the active site of esterase and its catalytic mechanism to hydrolyze the ester bond are elucidated by molecular dynamics (MD) simulation and QM/MM (Quantum mechanics/molecular mechanics) calculations, respectively. Fluorescent image‐based analysis of the cellular environment reveals that our probe can distinguish between live and dead cells based on esterase enzyme activity. [ABSTRACT FROM AUTHOR]

A novel zwitterionic near-infrared (NIR) dye, ZWCC, has been designed and synthesized. It shows significantly enhanced photostability and chemical stability compared to the existing zwitterionic NIR dye. In addition, the feasibility of labeling ZWCC with biological ligands was investigated and used in live cell imaging applications. [ABSTRACT FROM AUTHOR]

The glucose-6-phosphate dehydrogenase (G6PD) deficiency is X-linked and is the most common enzymatic deficiency disorder globally. It is a crucial enzyme for the pentose phosphate pathway and produces NADPH, which plays a vital role in regulating the oxidative stress of many cell types. The deficiency of G6PD primarily causes hemolytic anemia under oxidative stress triggered by food, drugs, or infection. G6PD-deficient patients infected with SARS-CoV-2 showed an increase in hemolysis and thrombosis. Patients also exhibited prolonged COVID-19 symptoms, ventilation support, neurological impacts, and high mortality. However, the mechanism of COVID-19 severity in G6PD deficient patients and its neurological manifestation is still ambiguous. Here, using a CRISPR-edited G6PD deficient human microglia cell culture model, we observed a significant reduction in NADPH level and an increase in basal reactive oxygen species (ROS) in microglia. Interestingly, the deficiency of the G6PD-NAPDH axis impairs induced nitric oxide synthase (iNOS) mediated nitric oxide (NO) production, which plays a fundamental role in inhibiting viral replication. Surprisingly, we also observed that the deficiency of the G6PD-NADPH axis reduced lysosomal acidification and free radical production, further abrogating the lysosomal clearance of viral particles. Thus, impairment of NO production, lysosomal functions, and redox dysregulation in G6PD deficient microglia altered innate immune response, promoting the severity of SARS-CoV-2 pathogenesis. [Display omitted] • The G6PD-NADPH axis plays a significant role in microglial NO production. • Deficiency of the G6PD-NADPH axis impaired lysosomal acidification in microglia by altering the function of TASL-NOX and HVCN1. • G6PD-deficient microglia are insensitive to LPS-mediated ROS generation. • The G6PD-NADPH axis plays an important role in microglial innate immune responses and clearance of viral particles. [ABSTRACT FROM AUTHOR]

A unique and highly water-soluble ICT-based fluorescent probe is developed for efficient detection and discrimination of reactive monocarbonyl formaldehyde (FA) from dicarbonyl methylglyoxal (MGO)/glyoxal (GO) by modulating the ICT process, which was confirmed by photophysical and TD-DFT analysis. The probe is applied in cellular imaging and quantifying FA in preserved food and MGO in manuka honey. [ABSTRACT FROM AUTHOR]

Organelle‐targeted photosensitizers with luminescence properties are potential theranostic agents for simultaneous imaging and photodynamic therapy. Described herein is a cyclometalated IrIII complex, Ir‐Bp‐Ly, that exhibits high triplet quantum yield and singlet‐oxygen‐generation efficiency. The close‐proximity energy levels between triplet energy states of Ir‐Bp‐Ly and molecular oxygen favors efficient singlet oxygen and reactive oxygen species (ROS) generation. The good lysosomal specificity of Ir‐Bp‐Ly leads to its increased efficacy as a photodynamic therapeutic and imaging agent. More information can be found in the Full Paper by A. Ajayaghosh et al. on page 10999 ff. [ABSTRACT FROM AUTHOR]

A diradical approach to obtain stable organic dyes with intense absorption around λ=1100 nm is reported. The para- and meta-quinodimethane-bridged BODIPY dimers BD-1 and BD-2 were synthesized and were found to have a small amount of diradical character. These molecules exhibited very intense absorption at λ=1088 nm ( ɛ=6.65×105 M−1 cm−1) and 1136 nm ( ɛ=6.44×105 M−1 cm−1), respectively, together with large two-photon-absorption cross-sections. Structural isomerization induced little variation in their diradical character but distinctive differences in their physical properties. Moreover, the compounds showed a selective fluorescence turn-on response in the presence of the hydroxyl radical but not with other reactive oxygen species. [ABSTRACT FROM AUTHOR]

A diradical approach to obtain stable organic dyes with intense absorption around λ=1100 nm is reported. The para- and meta-quinodimethane-bridged BODIPY dimers BD-1 and BD-2 were synthesized and were found to have a small amount of diradical character. These molecules exhibited very intense absorption at λ=1088 nm ( ɛ=6.65×105 M−1 cm−1) and 1136 nm ( ɛ=6.44×105 M−1 cm−1), respectively, together with large two-photon-absorption cross-sections. Structural isomerization induced little variation in their diradical character but distinctive differences in their physical properties. Moreover, the compounds showed a selective fluorescence turn-on response in the presence of the hydroxyl radical but not with other reactive oxygen species. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform-dye-assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H2S is combined with UCNPs and results in a library of H2S sensors with responsive emission signals ranging from the visible to the near-infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H2S in vitro and in cells. Furthermore, H2S levels in blood can be detected using the developed nanoprobes. Hence the reported H2S sensing platform can serve as a powerful diagnostic tool to research H2S functions and to investigate H2S-related diseases. [ABSTRACT FROM AUTHOR]

A 241-membered cyanine-based library was constructed by the combinatorial chemistry strategy. Combined with high-throughput screening, we successfully discovered a novel fluorescent probe (CyC-M716) capable of identifying a subset of parallel G-quadruplexes with propeller loops stretching across three tetrad layers with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Summary Long-term real-time visualization of lysosomal dynamics has been challenging at the onset of mitosis due to the lack of fluorescent probes enabling convenient imaging of dividing cells. We developed a long-term real-time photostable mitotic or proliferating marker, CDy6, a BODIPY-derived compound of designation yellow 6, which labels lysosome. In long-term real-time, CDy6 displayed a sharp increase in intensity and change in localization in mitosis, improved photostability, and decreased toxicity compared with other widely used lysosomal and DNA markers, and the ability to label cells in mouse xenograft models. Therefore, CDy6 may open new possibilities to target and trace lysosomal contents during mitosis and to monitor cell proliferation, which can further our knowledge of the basic underlying biological mechanisms in the management of cancer. [ABSTRACT FROM AUTHOR]

Development of highly sensitive and selective sensing systems of divalent zinc ion (Zn2+) in organisms has been a growing interest in the past decades owing to its pivotal role in cellular metabolism, apoptosis, and neurotransmission. Herein, we report the rational design and synthesis of a Zn2+ fluorescent-based probe by assembling lanthanide-doped upconversion nanoparticles (UCNPs) with chromophores. Specifically, upconversion luminescence (UCL) can be effectively quenched by the chromophores on the surface of nanoparticles via a fluorescence resonant energy transfer (FRET) process and subsequently recovered upon the addition of Zn2+, thus allowing for quantitative monitoring of Zn2+. Importantly, the sensing system enables detection of Zn2+ in real biological samples. We demonstrate that this chromophore-UCNP nanosystem is capable of implementing an efficient in vitro and in vivo detection of Zn2+ in mouse brain slice with Alzheimer's disease and zebrafish, respectively. [ABSTRACT FROM AUTHOR]

The first fluorescent sensor for milk fat was developed. It exhibited a magnificent, yet selective turn-on feature towards fat molecules in a complicated milk matrix by a disaggregation-induced emission mechanism. Further construction of a handy fluorescence milk fat detector provided a convenient rapid tool to measure the fat amount quantitatively. This discovery may help enhance the milk quality control process. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report a BODIPY-based turn-on fluorescent bisphenol A sensor. [•] We tested the superior selectivity toward BPA against several bisphenol analogs and phenol. [•] We demonstrated the stability and robustness of this probe for analyzing BPA in real, complex water samples. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S), an essential neurotransmitter, regulates physiological processes, including brain function. Lower level of endogenously produced H 2 S may lead to Alzheimer's disease (AD), which is a progressive neurodegenerative disorder characterized by the deposition and aggregation of amyloid-beta (Aβ) peptides in the brain tissue. Developing a molecular probe enabling sensing and visualizing of Aβ-disaggregates caused by H 2 S would be a potential therapeutic benefit for Alzheimer's disease. Herein, we report a rational design and synthesis of an orthogonally substituted tetraphenylethylene (TPE) dual functional turn-on molecular luminophore TPE-NBD-D. The current strategy centers on a TPE-core appended with an ancillary H 2 S sensing unit i.e., 4-chloro-7-nitrobenzofurazan (NBD) and a disulfide linked donor (D: 4-(pyridin-2-yldisulfaneyl)-benzoate) as a source of H 2 S in presence of bio-thiols. The disulfide-linked H 2 S-donor is cleaved off from the TPE by esterase and its counterpart exhibited a turn-on fluorescence response after releasing NBD ligand in bio-thiol environments. Molecular probe TPE-NBD-D, showed a marked efficiency to detect H 2 S in solution state (LOD 0.1 µM) through AIE phenomenon and featured its aqueous solubility, cell membrane permeability, low cytotoxicity and high selectivity towards H 2 S. The probe enabled to detect intracellular H 2 S in neuroblastoma cell line SHSY-5Y as reflected by the turn-on fluorescence. Further, the TPE-NBD-D has been employed in vivo mice model where the probe is capable of releasing H 2 S in thiol abundant colorectal area and opens up a new insight to understand the involvement of H 2 S releasing molecules in the management of Alzheimer's disease (AD). Eventually, the H 2 S production by TPE-NBD-D has been demonstrated to induce the Aβ 1–42 de-agglomeration which is meticulously monitored by the AFM, SEM and Raman fingerprint analysis of the model agglomerated form of Aβ 1–42 protein. This is the first time, we revealed TPE-structured molecular probe enabling as H 2 S donor and utilized for amyloid beta de-agglomeration without imparting any cytotoxicity. Therefore, this probe may be a potential chemical tool for the diagnosis and treatment of AD. [Display omitted] Design, synthesis and characterization of molecular probe, TPE-NBD-D, having the efficiency of endogenous H 2 S detection as well as H 2 S production which has been implemented to induce Aβ 1–42 de-agglomeration for the therapeutic benefit of Alzheimer's disease. • A molecular probe with tetraphenylethylene framework was develpoed for the detection of intracellular H 2 S. • Molecular probe TPE-NBD-D is capable of releasing H 2 S in colorectal area of mice. • The H 2 S production by TPE-NBD-D has been demonstrated to induce the Aβ 1–42 de-agglomeration. [ABSTRACT FROM AUTHOR]

The first BODIPY library (BD) was synthesized, and a highly selective glucagon sensor, Glucagon Yellow (BD-105), was discovered by fluorescence image-based screening method. BD library was synthesized via a Knoevenagel-type condensation reaction with 160 benzaldehydes and the 1,3 dimethyl- BODIPY scaffold. Using BD compounds, a fluorescence image-based screening was performed against three cell lines including AIphaTC1 and BetaTC6 cells which secret glucagon and insulin, respectively, and HeLa as control cells. Out of the 160 candidate probes, one compound, Glucagon Yellow, exhibited selective staining only in AlphaTC1 cells. The selectivity of Glucagon Yellow toward glucagon was confirmed in vitro by comparison of its fluorescence intensity change against 19 biologically relevant analytes. Subsequent immunostaining experiments revealed that Glucagon Yellow and the glucagon antibody colocalized in pancreas tissue, showing a high quantitative correlation analysis by the Pearson's coefficient constant (Rr = 0.950). These results demonstrated the potential application of Glucagon Yellow as a glucagon imaging agent in live cells and tissues. [ABSTRACT FROM AUTHOR]

Visualization of macrophages in live animals has been of great interest for a better understanding of inflammation. We developed a near infrared (NIR) probe CDnir7 that can selectively detect macrophages and visualize inflammation in vivo using the IVIS spectrum, Fluorescence Molecular Tomography (FMT) and Multi-Spectral Optoacoustic Tomography (MSOT). [ABSTRACT FROM AUTHOR]

Formaldehyde (FA), a simple reactive carbonyl molecule, is endogenously produced in the cell at various physiological condition. At elevated level, FA causes severe cell toxicity as well as damage in macromolecules such proteins and DNA. For detecting FA in living cell, we identify a small but effective fluorescent turn on probe comprising single benzene-based orothophenylenediamine compound. Further study reveals that carboxylic group in orothophenylenediamine plays the important role in enhancing fluorescent signal than another electron withdrawing group. It is even interesting to observe the occurrence of fluorescent enhancement in glutathione (GSH) environment which is generally abundant in every cell. Our probe enables to detect FA over other bio-analytes efficiently with limit of detection of 123 nM and 355-fold of enhancement in cellular mimicking conditions. Moreover, this probe could be useful in discriminating cell that has high concentration of FA as well as GSH. Single benzene, 3,4-Diaminobenzoic acid (DAB) is an efficient "turn on" fluorescent sensor for formaldehyde. Glutathione, a highly abundant tripeptide in cells acts as an amplifier towards fluorescence intensity and wavelength shifting at elevated level of formaldehyde and shows its applicability in cellular imaging. Unlabelled Image • A single benzene-based fluorescent probe was developed for sensing formaldehyde. • Orothophenylenediamine (OPD) derivative is selective towards only formaldehyde in PBS buffer solution instead nitric oxide. • Efficient detection of FA in GSH medium with an emission color change indicating the suitability for cellular imaging. • This probe was successfully applied to monitor FA with and without exogenous GSH in living HeLa, HepG2 and WI38 cells. [ABSTRACT FROM AUTHOR]

Reactive carbonyl species (RCSs) including one carbon formaldehyde (FA) and dicarbonyl compounds such as methylglyoxal (MGO) and glyoxal (GO) are produced during demethylase reactions and various glucose metabolic pathways respectively. Elevation of the RCSs concentrations in cells is due to abnormal DNA damage, glycation adducts with macromolecules that lead to various neurotoxic diseases. Hence, regular monitoring of these RCSs with an easy tool is of utmost interest. However, conventional methods such as chromatography and mass spectrometry for the detection of these species are not so economically viable. These issues were well addressed by the non-invasive reactivity-based fluorescence techniques. However, tedious synthesis, only specific to either mono aldehyde is limited to detect multiple RCSs in physiologies by synthesized fluorophores. An alternative, simple small molecules are widely applied as commercial biomarkers such as terephthalate and 2,3-diaminonaphthalene (NAP) for hydroxy radical (OH·) and nitric oxide (NO) respectively. Herein, we report an analogue of NAP, 1,8-diamino naphthalene (DAN) is an efficient chemosensor for highly sensitive detection of FA, MGO and GO with minimum detection limits of 0.95–3.97 μM. Surprisingly, DAN shows a "turn on" response towards RCSs but remaining silent towards NO which are exactly opposite to commercial probe NAP. Exogenous RCSs imaging in vitro cancerous cells shows the efficacy of the probe and its potential application for RCSs monitoring in cancer cells, generation of toxic byproducts. Unlabelled Image • A naphthalene based "turn on" fluorescent probe was developed for sensing reactive carbonyl species (FA, MGO, GO). • 1–8 diamines in naphthalene play crucial roles for selective sensing carbonyls but remaining silent towards nitric oxide. • Very fast response fluorescent probe is highly efficient for imaging of extracellular carbonyls in cancer cells. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide is regarded as one of the most significant gas signaling molecules for a variety of physiological and pathological processes. On page 191, L. Yuan, Y.‐T. Chang, and co‐workers design a H2S sensing nanoplatform based on dye assembled upconversion nanoparticles. These powerful sensors demonstrate highly selective and rapid responses to H2S in vitro and in cells, for a variety of applications in environmental and bioimaging fields. [ABSTRACT FROM AUTHOR]