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[Display omitted] • Developed a novel near-infrared fluorescent probe, NRO-βgal, for detecting endogenous β-galactosidase. • The probe demonstrated high selectivity and sensitivity towards β-galactosidase with a low detection limit (LOD = 0.2 U/L) and rapid response time (within 10 min). • NRO-βgal enables effective imaging of β-galactosidase levels in ovarian cancer mouse models, contributing to advancements in tumor detection and surgical interventions. The advancement of biological imaging techniques critically depends on the development of novel near-infrared (NIR) fluorescent probes. In this study, we introduce a designed NIR fluorescent probe, NRO-βgal, which exhibits a unique off–on response mechanism to β-galactosidase (β-gal). Emitting a fluorescence peak at a wavelength of 670 nm, NRO-βgal showcases a significant Stokes shift of 85 nm, which is indicative of its efficient energy transfer and minimized background interference. The probe achieves a remarkably low in vitro detection limit of 0.2 U/L and demonstrates a rapid response within 10 min, thereby underscoring its exceptional sensitivity, selectivity, and operational swiftness. Such superior analytical performance broadens the horizon for its application in intricate biological imaging studies. To validate the practical utility of NRO-βgal in bio-imaging, we employed ovarian cancer cell and mouse models, where the probe's efficacy in accurately delineating tumor cells was examined. The results affirm NRO-βgal's capability to provide sharp, high-contrast images of tumor regions, thereby significantly enhancing the precision of surgical tumor resection. Furthermore, the probe's potential for real-time monitoring of enzymatic activity in living tissues underscores its utility as a powerful tool for diagnostics in oncology and beyond. [ABSTRACT FROM AUTHOR]

A trivalent chromium (Cr 3 + ) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine–crown ether conjugate. This probe displayed a favorable selectivity for Cr 3 + over a range of other common metal ions in DMF/H 2 O (3:7, v / v ; PBS buffer 50 mmol L − 1 ; pH = 6.8) solution, leading to prominent fluorescence “OFF–ON” switching of the rhodamine fluorophore. The limit of detection was calculated to be 1.5 μmol L − 1 (S/N = 3). The binding ratio of RhC–Cr 3 + complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr 3 + in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 μmol L − 1 , and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr 3 + in living cells with a fluorescence enhancement signal. [ABSTRACT FROM AUTHOR]

In this work, two novel fluorescence probes, named as RBQ1 and RBQ2, were designed and synthesized based on rhodamine B lactam. RBQ1 was employed for sensitive fluorometric sensing of H + in the pH range of 2–4. Since RBQ1 exhibits color responses toward Cu 2+ , it was also employed for sensitive detection of Cu 2+ by photoelectric colorimetry. By using RBQ1 as the fluorescence probe, the detection limit of Cu 2+ obtained was 0.0365 μmol L −1 . RBQ2, with a similar chemical structure to RBQ1, also shows obvious fluorescence responses to H + , but no response to any metal ions. By using H + and Cu 2+ ions as chemical inputs and fluorescence or absorbance as outputs, a novel dual-mode molecular logic gate was constructed with RBQ1. [ABSTRACT FROM AUTHOR]

In this work, a novel phenoxazine-based fluorescent probe BPO - N 3 was developed to detect H 2 S. The results showed that the probe had high selectivity and sensitivity toward H 2 S, and its detection mechanism was based the ratio between green and red fluorescence signals; its detection limit was as low as 30 nM. The fluorescent imaging experiments further showed that the probe BPO - N 3 could successfully detect endogenous and exogenous H 2 S in living cells. This probe can be used as a powerful tool for in-depth study of H 2 S function in various physiological processes. Unlabelled Image • A novel phenoxazine-based fluorescent probe BPO-N 3 was developed to detect H 2 S. • Linear response (0.1 to 20 μM), high selectivity and sensitivity (LOD = 30 nM) were observed. • The probe BPO-N 3 could successfully detect endogenous and exogenous H 2 S in living cells. [ABSTRACT FROM AUTHOR]