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Owing to societal development and aging population, the impact of cancer on human health and quality of life has increased. Early detection and surgical treatment are the most effective approaches for most cancer patients. As the scope of conventional tumor resection is determined by auxiliary examination and surgeon experience, there is often insufficient recognition of tiny tumors. The ability to detect such tumors can be improved by using fluorescent tumor-specific probes for surgical navigation. This review mainly describes the design principles and mechanisms of activatable probes for the fluorescence imaging of tumors. This type of probe is nonfluorescent in normal tissue but exhibits obvious fluorescence emission upon encountering tumor-specific substrates, such as enzymes or bioactive molecules, or changes in the microenvironment, such as a low pH. In some cases, a single-factor response does not guarantee the effective fluorescence labeling of tumors. Therefore, two-factor-activatable fluorescence imaging probes that react with two specific factors in tumor cells have also been developed. Compared with single biomarker testing, the simultaneous monitoring of multiple biomarkers may provide additional insight into the role of these substances in cancer development and aid in improving the accuracy of early cancer diagnosis. Research and progress in this field can provide new methods for precision medicine and targeted therapy. The development of new approaches for early diagnosis and treatment can effectively improve the prognosis of cancer patients and help enhance their quality of life. [ABSTRACT FROM AUTHOR]

Cordycepin (3′‐deoxyadenosine) has a demonstrated value in ameliorating nonalcoholic steatohepatitis (NASH); however, its short in vivo metabolism time and high dose‐induced cytotoxicity are challenges limiting its clinical application. Herein, a cordycepin‐loaded macrophage vesicle (C‐MV) is developed for targeted cordycepin delivery to achieve stable and durable mitigation of NASH. The C‐MV is obtained using cytochalasin B‐stimulated RAW 264.7 cells to produce MV, followed by repeated freeze‐thawing and extrusion of MV and cordycepin. C‐MV selectively delivers cordycepin to macrophages at the site of liver injury, slowly releases cordycepin, reduces the toxicity associated with high cordycepin doses, and increases the mice's survival rate from 40% to 90%. Moreover, C‐MV reduces liver apoptosis and attenuated NASH liver injury by activating AMP‐activated protein kinase and inhibiting caspase 6 activity. Overall, C‐MV exhibits better anti‐inflammatory, lipid‐lowering, and anti‐apoptosis properties than free cordycepin, making it a promising delivery system for the potential clinical application of cordycepin. MV combined with cordycepin provides an inspiring bionic strategy for NASH treatment that can achieve effective therapeutic effects in vivo. [ABSTRACT FROM AUTHOR]

Here, we designed and synthesized two fluorescent probes for detecting phosgene by nucleophilic substitution reaction using BODIPY as a fluorophore and 2-aminobenzylamine as reactive functional group. For the first time, we have studied the similarities and differences between asymmetric monosubstituted (1) and symmetric disubstituted (2) probes. A monosubstituted probe 1 (having a 2-aminobenzylamine group at the 3-position of BODIPY) has fluorescence-enhancing (weak green fluorescence to strong green fluorescence) responce to phosgene in 30 s with a large Stokes shift (∼70 nm) and sensitive property (DL = 0.81 nM); while the disubstituted probe 2 (having two 2-aminobenzylamine groups at the 3, 5-position of BODIPY) has a ratiometric fluorescent responce to phosgene in 2 min. The linear range of the response is wider than that of the monosubstitution probe 1 , and the detection limit is also lower (2.36 nM). In addition, probes 1 and 2 can effectively eliminate the interference of other substances with similar chemical structure as phosgene. They can not only detect phosgene in solution environment, but also in gaseous environment quickly and sensitively. "for TOC only". Image 1 • The similarities and differences between monosubstituted and disubstituted probes are investigated for the first time. • The design and synthesis of 1 and 2 are novel and simple, and the spectrum of 1 and 2 both have large Stokes shift. • The probes 1 and 2 exhibit high sensitivity, high selectivity and very low detection limits for detection of phosgene. •.The probes 1 and 2 can be used for the detection of phosgene in solution and in gaseous quickly and sensitively. [ABSTRACT FROM AUTHOR]

The mechanochromic luminescence phenomenon was first reported in the low-cost mechanochemical (MC) synthesis process of a covalent organic framework (COF-TpMA (MC)) prepared using triformylphloroglucinol (Tp) and melamine (MA) as precursors, which shows excellent performance as a hydroxyl radical (ṖOH) detector in living systems. This work not only shows a new kind of mechanochromic luminescent material but also exhibits a close relationship between the π–π stacking and luminescence properties of COF materials. [ABSTRACT FROM AUTHOR]

A new highly selective fluorescent chemosensor for formaldehyde (FA) has been synthesized based on boron dipyrromethene as fluorophore and o-phenylenediamine ( OPDA ) as reaction group. When FA is added, the fluorescence emission band of the chemosensor red shift (from 525 nm to 548 nm) accompanied by an increase in intensity with strong green fluorescence was observed. This chemosensor also exhibited the lowest detection limit (0.104 μM) distinguished with other articles that have been reported. The application to cellular fluorescence imaging or test papers detection both indicated that the probe was highly responsive to the FA in endogenous cells and in the gaseous environment. [ABSTRACT FROM AUTHOR]

Two fluorescent, m-nitrophenol-substituted difluoroboron dipyrromethene dyes have been designed by nucleophilic substitution reaction of 3,5-dichloro-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). Nonsymmetric and symmetric probes, that is. BODIPY 1 (with one nitrophenol group at the position 3) and BODIPY 2 (with two nitrophenol groups at the positions 3 and 5) were applied to ratiometric fluorescent glutathione detection. The detection is based on the two-step nucleophilic aromatic substitution of the nitrophenol groups of the probes by glutathione in buffer solution containing CTAB. In the first stage, probe 1 showed ratiometric fluorescent color change from green (λem = 530 nm) to yellow (λem = 561 nm) because of monosubstitution with glutathione (I561nm/I530nm). Addition of excess glutathione caused the second stage of ratiometric fluorescent color change from yellow to reddish orange (λem = 596 nm, I596nm/ I561nm) due to disubstitution with glutathione. Therefore, different concentration ranges of glutathione (from less to excess) could be rapidly detected by the two-stage ratiometric fluorescent probe 1 in 5 min. While, probe 2 shows single-stage ratiometric fluorescent detection to GSH (from green to reddish orange, I596nm/I535nm). Probes 1 and 2 exhibit excellent properties with sensitive, specific colorimetric response and ratiometric fluorescent response to glutathione over other sulfur nucleophiles. Application to cellular ratiometric fluorescence imaging indicated that the probes were highly responsive to intracellular glutathione. [ABSTRACT FROM AUTHOR]

Herein a phenylselenium-substituted BODIPY (1) fluorescent turn-off sensor was developed for the purpose to achieve excellent selectivity and sensitivity for H2S detection based on the substitution reaction of the phenylselenide group at the 3-position with H2S. The excess addition of hydrogen sulfide promoted further substitution of the phenylselenide group at the 5-position of the probe and was accompanied by a further decrease in fluorescence emission intensity. Sensor 1 demonstrated remarkable performance with 49-fold red color fluorescence intensity decrease at longer excitation wavelength, a low detection limit (0.0025 μM), and specific fluorescent response toward H2S over anions, biothiols, and other amino acids in neutral media. It showed no obvious cell toxicity and good membrane permeability, which was well exploited for intracellular H2S detection and imaging through fluorescence microscopy imaging. [ABSTRACT FROM AUTHOR]

A highly selective fluorescent indicator for copper, substituted with a 1-(furan-2-yl)-N-((pyridin-2-yl) methyl)methanamine (FPA) group at the position 3 or 5 of the BODIPY has been synthesized. The BODIPY indicator forms 1:1 complexes with Cu 2+ ions producing large bathochromic shifts in the absorption (from 480 nm to 570 nm) and fluorescence spectra (from 550 nm to 600 nm) with a change of solution color and cation-induced fluorescence amplifications. The new boradiazaindacene dye exhibited a high affinity and selectivity for Cu 2+ over competing metal ions. Confocal microscopy experiments showed that bodipy-FPA can be used for detection of Cu 2+ levels within living cells. [ABSTRACT FROM AUTHOR]

• H 2 S causes hydrolysis of the furan ring while nucleophilic addition occurs on the double bond of vinylfuran. • The addition of H 2 S causes the strong fluorescence emission. • BODIPY-vinylfuran is highly responsive to both endogenous and exogenous H 2 S. • BODIPY-vinylfuran has good selectivity, high sensitivity, low detection limit and real-time detection. In this work, a fluorescent H 2 S turn on probe BODIPY- vinylfuran has been synthesized by reaction of 8-methyl-BODIPY with functional group 5-methylfuranal. When H 2 S is present, the furan ring is hydrolyzed and ring-opened, and H 2 S further undergoes a nucleophilic addition reaction with carbon-carbon double bond (C C) of vinylfuran, resulting in enhanced fluorescence. Due to the addition reaction of carbon-carbon double bond with H 2 S, the π-π conjugated structure of furan and BODIPY is destroyed, resulting in the shifting of maximum emission peak from 535 nm to 496 nm. Sensor BODIPY- vinylfuran demonstrates remarkable performance with more than 150-folds increase in fluorescence intensity, low detection limit (99.4 nM) and selectivity to H 2 S specificity. Furthermore, BODIPY-vinylfuran possesses low cytotoxicity and good biocompatibility. Cellular fluorescence imaging further demonstrates that BODIPY-vinylfuran is highly responsive to both endogenous and exogenous H 2 S. [ABSTRACT FROM AUTHOR]

Two new 4,4-difluoro-4-bora-3a,4a-diaza- s -indacene (BODIPY) dyes ( 1 and 2 ) with piperazine subunits on position 3 or 5 were synthesized. Their absorption and steady-state fluorescence properties were investigated as a function of solvent. In water/MeCN (9:1, V/V) solution, the dyes show fluorescent enhancement upon increasing the acidity of the solution. They can be used in water/MeCN (9:1, V/V) solution as fluorescent pH probes excitable with visible light, with p K a values near-neutral (around 6.5 and 6.8). Dyes 1 and 2 are readily taken up by biological cells in the cytosol where it has no obvious toxic effects. [ABSTRACT FROM AUTHOR]

A new kind of convenient, low-cost, environmentally friendly, and simple one step synthetic route for the preparation of C-dots-based CDs (CA + Phen) fluorescent turn-off probe for Fe 2+ and Fe 3+ from 1,10-phenanthroline (Phen) using anhydrous citric acid (CA) as the sole precursor without any solvents by solid state method. Only the Fe 2+ and Fe 3+ can readily quench the fluorescence of the CDs (CA + Phen), indicating a remarkably high selectivity towards Fe 2+ and Fe 3+ over other metals with a detection limit as low as 20 nM and 35 nM. The CDs (CA + Phen) exhibited a low cytotoxicity and could label the HK-2 cells. Additionally, this CDs (CA + Phen) has been successfully applied for the determination of Fe in real sample of milk. Endowed with relatively high sensitivity and selectivity, the present sensor holds the potential to be applied for the detection of Fe 2+ and Fe 3+ in aqueous media. [ABSTRACT FROM AUTHOR]

We report the preparation of a small library of copper-based metallenes, such as copperene, brassene, bronzene, cupronickelene and AlCuZn trimetallene, via a cryo-pretreatment assisted liquid phase exfoliation method. To the best of our knowledge, these nanosheets may represent a new category of metallenes. Benefiting from mixed-valence copper-induced oxidative stress and cleavage effects of layered structures, the obtained metallenes could efficiently eliminate drug-resistant bacteria even at a concentration as low as 1 μg mL -1 . Due to the alloy engineering-induced change in the release rate of metal ions, the CuZn metallene exhibited a much better antibacterial ability than the other metallenes and three clinical antibiotics. We believe this work not only expands the category of emerging 2D metallenes, but also proposes a strategy combining 2D and alloy engineering to improve the antibacterial properties of copper-based materials.

The mechanochromic luminescence phenomenon was first reported in the low-cost mechanochemical (MC) synthesis process of a covalent organic framework (COF-TpMA (MC)) prepared using triformylphloroglucinol (Tp) and melamine (MA) as precursors, which shows excellent performance as a hydroxyl radical (˙OH) detector in living systems. This work not only shows a new kind of mechanochromic luminescent material but also exhibits a close relationship between the π-π stacking and luminescence properties of COF materials.