Recent Progress of Small‐Molecule Ratiometric Fluorescent Probes for Peroxynitrite in Biological Systems

Abstract

Peroxynitrite (ONOO À ) as a major reactive oxygen species plays important roles in cellular signal transduction and homeostatic regulation. Precise detection of ONOO À in biological systems is vital for exploring its physiological and pathological function. Among numerous detection methods, fluorescence imaging technology using fluorescent probes offers some advantages, including simple operation, high sensitivity and selectivity, as well as real-time and nondestructive detection. In particular, ratiometric fluorescent probes, in which the built-in calibration of the two emission bands prevents interference from the biological environment, have been extensively employed to monitor the fluctuation of bioactive species. In this review, we will discuss smallmolecule ratiometric fluorescent probes for ONOO À in live cells or in vivo, which involves chemical structures, response mechanisms, and biological applications. Moreover, the challenges and future prospects of ONOO À -responsive ratiometric fluorescent probe are also proposed.

Vision for Ratiometric Nanoprobes: In Vivo Noninvasive Visualization and Readout of Physiological Hallmarks

“…The recognition units incorporated in the structure of certain RNPs might lack specificity toward the analyte of interest, in some cases. For instance, hydrazide compounds and diphenyl phosphinate, which have been extensively employed as the ONOO – -sensitive moieties in RNPs, can also react with O 2 •– and HClO species, respectively. ,− As another example, although C=C or C=N bond in the structure can be regarded as the recognition sites for hydrogen sulfide, some other entities such as thiols, hydroxyl groups and ONOO – would also be able to trigger a nucleophilic addition reaction with the bonds . Consequently, the issue might lead to the generation of false positive or negative signals while the corresponding probes are residing in the complex biological systems.…”

“…21,188−190 As another example, although C=C or C=N bond in the structure can be regarded as the recognition sites for hydrogen sulfide, some other entities such as thiols, hydroxyl groups and ONOO − would also be able to trigger a nucleophilic addition reaction with the bonds. 23 Consequently, the issue might lead to the generation of false positive or negative signals while the corresponding probes are residing in the complex biological systems. Thus, further attempts are expected to be made on introducing "super-exclusive" sets of recognition units to improve the specificity of certain measurements.…”

“…In contrast to single-intensity based methods, the ratiometric approach can quantitatively scrutinize the alteration in the level of physiological parameters, extending the applicability of the ratiometric probes to in vivo investigation of the origin and evolution of chronic diseases. The fast advances in nanomaterials development have enabled state-of-art in vivo ratiometric bioimaging of endogenous biological targets such as reactive oxygen species (ROS), , reactive nitrogen species (RNS), − reactive sulfur species (RSS), − derivations of amino acids, − ions, , etc . − However, there is still ample room to obtain more satisfactory results from most of these nanosystems either by manipulating the constituents of the probes to improve the imaging performance or minimizing the inevitable interference of environmental factors on the output signal.…”

Rational design of an iminocoumarin‐based fluorescence probe for peroxynitrite with high signal‐to‐noise ratio

“…Up to now, various techniques have been employed for monitoring ONOO À in living cells. Compared with conventional detection methods, fluorescence imaging technology is considered a potentially powerful method for visualizing ONOO À in biological processes due to its excellent temporal and spatial resolution [7][8][9]. Theoretically, a fluorescent probe is typically composed of a recognition unit and a fluorophore [10][11][12][13][14][15][16].…”

FRET Luminescent Probe for the Ratiometric Imaging of Peroxynitrite in Rat Brain Models of Epilepsy-Based on Organic Dye-Conjugated Iridium(III) Complex

“…Currently, numerous detection methods for ONOO – in vivo have been reported, and in which the luminescence probe method stands out for its high sensitivity, selectivity, minimal invasiveness, and ability to detect in real-time in situ. − While a diverse range of ONOO – detection probes are available, several challenges persist in monitoring ONOO – in the brains of epileptic patients. There are four primary challenges: (1) single-photon excitation probes are limited by tissue penetration depth; − (2) short-lived fluorescent probes are interfered from background fluorescent signals; (3) single-signal on–off typed luminescent probes are susceptible to optical bleaching, focal length changes, and laser intensity changes; , (4) ratiometric luminescent probes suffer from the spectral overlapping issue. , As a result, there has been considerable interest in two-photon luminescent probes for bioimaging, owing to their distinct advantages such as reduced background fluorescence interference, minimal tissue damage at low-energy excitation, and enhanced deep tissue imaging capabilities attributed to superior tissue penetration. ,− Additionally, the utilization of long-lived luminescent probes avoids the interference arising from the self-fluorescence of endogenous biological material and scattered light emitted by neighboring optical systems. , Furthermore, ratiometric luminescent probes employing the Förster resonance energy transfer (FRET) mechanism offer a viable solution to address the spectral overlap issue encountered between two emission peaks, thereby enhancing the sensitivity and precision of probe detection. ,− Hence, the strategic development of a two-photon excited, long-lived, and ratiometric luminescent probe emerges as a promising solution to address the aforementioned challenges, thereby enabling precise detection of physiologically active species within living organisms.…”