Salicylaldehyde built fluorescent probe for dual sensing of Al3+, Zn2+ ions: Applications in latent fingerprint, bio-imaging & real sample analysis

Imaging of zinc ions across diverse biological samples with a quinoline-based tris(2-pyridylmethyl)amine fluorescent probe

Zinc ions (Zn2⁺) is actively involved in diverse biological processes. Therefore, the precise detection of Zn2⁺ ion is an important object of increasing investigation. Although numerous fluorescent zinc ion detection probes have been developed, simple, biocompatible, and sensitive probes are still urgently needed. Herein, we reported two novel fluorescent probes, ZnTP1 and ZnTP2, by incorporating a quinoline fluorophore into a membrane-permeable zinc chelator tris(2-pyridylmethyl)amine. ZnTP1 exhibited a significant fluorescence enhancement in the presence of zinc ions through chelation-enhanced fluorescence (CHEF) processes, whereas probe ZnTP2 did not show any significant change in fluorescence due to the insertion of the carbonyl group. Further investigations revealed that ZnTP1 can effectively penetrate cell membranes and detect Zn2+ with high sensitivity in diverse biological samples, including living cells, plant tissues, and animal model zebrafish. This work suggests that ZnTP1 as a simple and efficient chemical probe has great potential for zinc ions detection in various biological contexts, thus providing a new tool for probing zinc ions in biosystems.

Multi-bioapplicable fluorescence chemosensor for sequentially identifying gallium ion and pyrophosphate: Application to environmental samples, human serum, zebrafish and celery

A multi-bioapplicable fluorescence chemosensor MQV, ((E)-2-methoxy-6-((2-(quinolin-2-yl)hydrazineylidene)methyl)phenol), was developed for sequential detection of Ga3+ and pyrophosphate (PPi) ions. The addition of Ga3+ and PPi to MQV in sequence strongly caused an off-on-off fluorescent response in PBS buffer/DMSO (8:2, v/v, pH 7.4). The detection limits of MQV to Ga3+ and PPi were calculated as 3.00 μM and 4.49 μM, respectively. The 1:1 association mechanism of MQV to Ga3+ was determined using 1H NMR titration, Job plot and DFT calculations. The reliability of MQV for the practical detection of Ga3+ and PPi was demonstrated in real water samples like drinking, tap, river, seawater, and sewage. Notely, we affirmed the possibility for sequential detection of Ga3+ and PPi by MQV in biological systems such as human blood serum, living zebrafish, and fresh celery. In human serum, MQV signaled linearly in 0-125 μM toward Ga3+ and PPi under detection limits of 10.50 μM and 12.94 μM, respectively. Surprisingly, MQV is the first case to detect Ga3+via fluorescence change in plant and to sequentially detect Ga3+ and PPi in living zebrafish and plant.

AIE Active Imidazole-Stilbene Conjugated Fluorescent Probes: Illuminating Latent Fingerprints and Advancing Anticounterfeiting Technologies

Aggregation-induced emission luminogens (AIEgens) are widely used in the realm of latent fingerprint visualization owing to their luminosity and resistance to photobleaching. However, challenges such as significant background interference and limited resolution hinder their rapid advancement. Consequently, there is a pressing need to improve the detailed visualization of latent fingerprint (LFP) imaging, particularly for analyzing level 3 details. To address this, we have designed donor-acceptor (D-A) type AIEgens named MMIMV, DMIMV, and TMIMV. These compounds exhibit robust emissions ranging from 481 to 552 nm and signify positive fluorosolvatochromism. When applied as powder dusting, these derivatives enable the fluorescence imaging of LFPs on various material substrates. The analysis of these imaged LFPs yields intricate details regarding fingerprint ridge patterns. Our results underscore the potential of highly emissive AIEgens MMIMV, DMIMV, and TMIMV as promising candidates for fingerprint visualization, thus offering significant implications for forensic investigations. Furthermore, these derivatives serve as effective fluorescent security inks for writing and drawing, presenting a novel avenue for robust anticounterfeiting applications.

A simple fluorescent probe for selectively detecting Al3+ and F- in living cells and growing tea plants

Aluminum (Al3+) and fluorine (F-) ions can be easily enriched in tea plants. When they excessively accumulate in tea, they can affect the health of tea lovers. Herein, a simple, highly sensitive and selective fluorescent probe (named BHMP) for Al3+ and F- detection was developed through a one-step condensation reaction, in which benzothiazole acted as a fluorophore and acceptor and hydrazine-Schiff base as a recognition unit. The probe was characterized comprehensively using spectroscopic methods, and the structure-activity relationship was systematically researched through crystal structure and theoretical calculations. Its sensitivity was measured via the fluorescent titration experiment, and the limit of detection (LOD) towards Al3+ was up to 1.04 × 10-8 mol L-1. Furthermore, we successfully utilized BHMP to visually detect the presence of Al3+ in living cells and tea tree roots through fluorescence confocal imaging. The successful detection of Al3+ in tea tree roots indicated that BHMP could be used as a candidate fluorescent chemosensor to dynamically monitor the variation in enriched Al3+ under the influence of the environment during tea tree growth. Our study provides a reference for the control of Al3+ concentration during the growth of tea plants and provides new insights into improving tea quality control.

Novel ratiometric fluorescent probe with large Stokes shift for selective sensing and imaging of Zn2+ in live cell

A novel ratiometric fluorescent probe, namely 5-[(3-dicyanoylidene -5.5-dimethyl) cyclohexenyl-1-ethenyl] salicylaldehyde-3'-hydroxybenzohydrazone (DCSH) is presented for the selective sensing of Zn2+ ion in acetonitrile/water (2/3, pH 7.4) solution. Introducing Zn2+ ions notably caused the peak emission of DCSH to shift from 560 nm to 646 nm, accompanied with a significant enhancement of its intensity. A vivid change in fluorescence color from yellow to red facilitated the immediate identification of Zn2+ ions by visual observation. DCSH exhibits substantial Stokes shifts (110 and 196 nm), rapid detection capability (within 10 s) and high sensitivity to Zn2+ ions, achieving a limit of detection of 31.2 nM. The response mechanism is supposed to involve the block of C = N bond isomerization and excited state intramolecular proton transfer (ESIPT) along with the enhancement of fluorescence through chelation (CHEF) effect. DCSH was effectively utilized for ratiometric fluorescence imaging to monitor exogenous Zn2+ concentrations in HeLa cells. Significantly, DCSH is capable of monitoring elevated levels of Zn2+ ion during apoptosis induced by L-Buthionine sulfoximine (BSO).

A mixed Ce/Eu metal-organic framework for ratiometric detection of Al3+ ion

As a heavy metal ion, excessive aluminum ions pose a serious threat to human health and the ecological environment. Developing a simple, efficient, and fast detection method to detect the content of aluminum ions is of great significance, especially for ensuring human health and ecological safety. Herein, the mixed rare earth metal-organic framework (Ce0.74Eu0.26TPTC and Ce0.62Eu0.38TPTC) were prepared based on simple ligand 1,1':4',1″-Terphenyl-2',4,4″,5'-tetracarboxylic acid (H4TPTC). The Ce0.74Eu0.26TPTC and Ce0.62Eu0.38TPTC have dual luminescence centers, which can be used as ratio fluorescent probes to detect Al3+ ions, making the detection results more accurate and reliable. Therefore, this work can promote the further development of rare earth-based MOFs in the detection of heavy metal ions.

Development of a bisphenol A based chemosensor for Al3+ and its application in cell imaging and plant root imaging

Bisphenol A is a fluorophoric platform that is used to develop chemosensors for various species. Herein, we report a bisphenol A based Schiff-base molecule, 4,4'-(propane-2,2-diyl)bis(2-((E)-((2-hydroxy-5-methylphenyl)imino)methyl)phenol) (Me-H4L), as a selective chemosensor for Al3+. Among the several metal ions, it shows a significant increment in its fluorescence intensity (50 fold) at 535 nm in the presence of Al3+ ions. The enhanced fluorescence was attributed to the CHEFF mechanism and inhibition of CN isomerization. The limit of detection value of Me-H4L for Al3+ was determined to be 9.65 μM. Its quantum yield and lifetime increased considerably in the presence of the cation. Some theoretical calculations were performed to explain the interaction between Al3+ and the probe. Furthermore, Me-H4L was applied in cell imaging studies using animal cells and plant roots.

Recent Advances in Organic Small-Molecule Fluorescent Probes for the Detection of Zinc Ions (Zn2+)

Zinc(II) ions (Zn2g) play crucial roles in the growth, propagation, and metabolism of animals, plants, and humans. Abnormal concentrations of Zn2+ in the environment and living organisms pose potential risks to environmental protection and human health. Therefore, it is imperative to develop rapid, reliable and in-situ detection methods for Zn2+ in both environmental and biological contexts. Furthermore, effective analytical methods are required for diagnosing diseases and understanding physiological metabolic mechanisms associated with Zn2+ concentration levels. Organic small-molecule fluorescent probes offer advantages such as fast, reliable, convenient, non-destructive detection capabilities and have significant application potential in Zn2+ detection and bioimaging; thus garnering extensive attention. Over the past two years alone, various organic small-molecule probes for Zn2+ based on different detection mechanisms and fluorophores have been rapidly developed. However, these probes still exhibit several limitations that need further resolution. In light of this context, we provide a comprehensive summary of the detection mechanisms, performance characteristics, and application scope of Zn2+ fluorescence probes since year 2022 while highlighting their advantages. We also propose solutions to address existing issues with these probes and outline future directions for their advancement. This review aims to serve as a valuable reference source offering insights into the development of advanced organic small-molecule-based fluorescence probes specifically designed for detecting Zn2+.

A novel Zn2+-coordination fluorescence probe for sensing HPPD inhibitors and its application in environmental media and biological imaging

Mesotrione, topramezone, tembotrione, and sulcotrione are four types of 4-hydroxyphenylpyruvate dioxidase (HPPD) inhibitor herbicides that are extensively employed in agricultural practices, but their usage also leads to environmental pollution and poses risks to human health. A probe (E)-1-((2-(pyridin-2-yl) hydrazineylidene) methyl) naphthalen-2-ol (CHMN) based on chelation enhancement (CHEF) effect synthesized. CHMN was first chelated with Zn2+ to form a probe system with green, which can be further used to detect mesotrione, topramezone, tembotrione and sulcotrione in complicated environment. CHMN-Zn2+ detection of four pesticides was accurate, with an excellent linear relationship between 0 and 100 μM. The detection limits were LODmesotrione = 7.79 μM, LODtopramezone = 1.91 μM, LODtembotrione = 1.38 μM and LODsulcotrione = 2.43 μM. The detection time is 1 min, and it is successfully applied in real water sample and bioimaging. This work can provide a novel method for studying the migration and behavior of environmental pollutants.