A ratiometric fluorescent probe based on benzothiazole with a large Stokes shift for fluoride ion sensing in living cells, animals and plants.

A Novel Bis(rhodamine)-Fluorene Hybrid for Monitoring of Aluminum, Mercury, and Cyanide in Water and Living Cells

Red-emissive fluorescent probes based on PET mechanism for highly sensitive detection and multi-scenario imaging of thiophenol.

Thiophenol (PhSH) is a highly toxic aromatic thiol endangering ecosystems, food safety, and human health. Traditional detection methods are limited by instrument dependence and inability for real-time imaging. This study developed a red-emitting fluorescent probe, TTCP-DN, based on the PET mechanism. The probe employs 5-(4-diphenylamino)benzothiophene as the fluorophore and 2,4-dinitrophenoxy as the PhSH-specific recognition moiety, achieving mitochondrial targeting via a pyridine salt. Without PhSH, fluorescence is quenched; upon PhSH-induced reaction, fluorescence restores at 623 nm. The probe has low detection limit (37.8 nM), large Stokes shift (153 nm), good biocompatibility, and high selectivity. It was applied for mitochondrial imaging in 4 T1 cells, qualitative detection and semi-quantitative concentration trend analysis of PhSH in zebrafish, plant tissues, environmental, food and biological samples (recoveries 95-105%), and fabricated into portable paper-based test strips. This work provides a versatile PhSH detection tool and a paradigm for targeted probes of toxic aromatic pollutants.

Cyanide-Triggered Fluorescence Turn-On in an Indole-Based Chemodosimeter.

Development of a ratiometric fluorescent probe for selective detection and bioimaging of hydrogen peroxide in HeLa cells and zebrafish.

Because intracellular H2O2 levels vary dynamically and are involved in both redox signaling and oxidative stress linked to human health and disease, quantitative fluorescent detection of H2O2 is essential in living systems. In this work, a carbazole-based ratiometric fluorescent probe, KD-H2O2, was designed and synthesized for the selective detection of H2O2. Performance evaluation demonstrated that KD-H2O2 exhibited excellent sensing properties, including a broad pH tolerance range (pH 3.0-11.0), high detection sensitivity with a low limit of detection (LOD) of 2.74 μM, and favorable biocompatibility and low cytotoxicity. Notably, upon reaction with H2O2, the probe solution exhibited a distinct colour change that could be readily observed with the naked eye. Furthermore, bioimaging experiments demonstrated that KD-H2O2 enabled visualization of endogenous and exogenous H2O2 in HeLa cells, and it could detect exogenous H2O2 in zebrafish. Overall, the probe is a reliable tool for monitoring dynamic H2O2 changes in biological systems and has potential biomedical applications.

A near-infrared AIE fluorescent probe for selective peroxynitrite (ONOO-) detection and bioimaging with anti-counterfeiting applications.

As a potent reactive nitrogen species characterized by robust oxidative capabilities, peroxynitrite (ONOO-) is fundamentally involved in diverse physiological and pathological events. To overcome the aggregation-caused quenching (ACQ) commonly encountered in traditional fluorophores, TriPS-py-BOO, a near-infrared AIE-active fluorescent probe, was rationally designed for the selective detection of ONOO-. This newly engineered probe demonstrates favorable sensing capabilities toward ONOO-, yielding low limits of detection at 0.573 μM (colorimetric) and 0.743 μM (fluorometric). Furthermore, its large Stokes shift of 235 nm substantially minimizes background auto-fluorescence during optical analysis. Benefiting from its favorable biocompatibility, the probe was successfully applied to imaging both exogenously added and intracellularly generated ONOO- in A549 cells, as well as exogenously added ONOO- in zebrafish. More importantly, the reaction product o-TriPS-py generated after ONOO- recognition displayed good photochromic behavior and acid-responsive properties, enabling its further application in molecular logic operations and intelligent anti-counterfeiting systems. This work not only provides an effective strategy for ONOO- sensing, but also offers a new approach for integrating fluorescence detection with multifunctional optical materials.

From colorimetric sensing to molecular logic: A Schiff Base probe for dual Cu2+ and Fe3+ recognition.

The development of efficient optical probes for the detection of biologically and environmentally important metal ions remains a significant research challenge. Herein, we report a Schiff base-derived colorimetric probe, (E)-2-((2-hydroxy-3-methoxybenzylidene)amino)benzamide (P), for the selective detection of Cu2+ and Fe3+ ions in a DMSO-H2O (1:9, v/v) medium. Probe P exhibits distinct colorimetric responses toward the target ions, accompanied by the appearance of new absorption bands at 409 nm for Cu2+ and 690 nm for Fe3+, enabling naked-eye discrimination. The sensing response arises from coordination-induced electronic redistribution within the probe framework. The probe displays high sensitivity, with detection limits of 0.83 μM for Cu2+ and 0.62 μM for Fe3+. A 1:1 binding stoichiometry was supported by Job's plot and ESI-MS analyses, while FTIR studies provided additional evidence for the proposed binding mode. Furthermore, density functional theory (DFT) calculations provided insight into the electronic features of the resulting complexes. The practical utility of the probe was demonstrated through the determination of Cu2+ and Fe3+ ions in water samples with satisfactory recoveries. In addition, the probe was employed to construct molecular logic operations, including INHIBIT and YES gates. These results highlight probe P as a simple, sensitive, and effective platform for dual-ion sensing and molecular logic applications.