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Organic phosphate biomolecules (OPBs) are indispensable components of eukaryotes and prokaryotes, such as acting as the fundamental components of cell membranes and important substrates for nucleic acids. They play pivotal roles in various biological processes, such as energy conservation, metabolism, and signal modulation. Due to the difficulty of detection caused by variety OPBs, investigation of their respective physiological effects in organisms has been restrained by the lack of efficient tools. Many small fluorescent probes have been employed for selective detection and monitoring of OPBs in vitro or in vivo due to the advantages of tailored properties, biodegradability and in situ high temporal and spatial resolution imaging. In this review, we summarize the recent advances in fluorescent probes for OPBs, such as nucleotides, NAD(P)H, FAD/FMN and PS. Importantly, we describe their identification mechanisms in detail and discuss the general strategies for these OPBs probe designs, which provide new insights and ideas for the future probe designs.

Thiophenols as high toxic environmental pollutants are poisonous for animals and aquatic organisms. Therefore, it is indispensable to monitor thiophenols in the environment. Herein, a novel near-infrared fluorescent probe was developed for the detection of thiophenols, which was easily prepared by one-step coupling of 2,4-dinitrobenzenesulfonyl chloride with Nile blue. The probe showed a significant near infrared (∼675 nm) fluorescence “turn-on” response to thiophenols with some good features including chromogenic reaction, high sensitivity and selectivity, fast response, near-infrared emission along with low detection limit (1.8 nM). The probe was employed to rapidly and visually determine thiophenols in several industrial wastewaters with good recoveries (90–110%). Moreover, this probe has been demonstrated good capability for imaging thiophenol in HeLa cells.

Sodium sulfite (Na2SO3) is widely used as a food additive, but the excessive residue of SO32− in food can cause irritative effects and damages to the human body. In this study, we reported a novel near-infrared (NIR) fluorescent probe (DCMQ) for visual detection of SO32− based on a chromogenic reaction. The probe can quantitatively determine SO32− with high specificity and sensitivity, fast response (

Hydrazine and bisulfite are poisonous to the environment and human health, hence it is necessary to monitor hydrazine and bisulfite in the environment and living cells. In this study, we reported a smart fluorescent probe (CMCA) for discriminative detection of hydrazine and bisulfite. The single fluorescent probe can respond to hydrazine and bisulfite with two different sets of colorimetric and ratiometric fluorescence signals together with high selectivity, fast response and low detection limit. The discriminative sensing behaviors of the probe for hydrazine and bisulfite were ascribed to different reaction mechanisms, which were confirmed by 1H NMR and HR-MS spectra. The probe has been successfully used to discriminatively determine hydrazine and bisulfite in industrial wastewater with good recoveries. Furthermore, the probe was employed to visualize hydrazine and bisulfite in live cells from different fluorescence channels with good performance. Therefore, this probe has great potential applications for discriminative detection of hydrazine and bisulfite in the environment and living cells.

A series of highly photostable, lysosome-targeted BODIPYs with tunable fluorescence from green to the near-infrared region was developed. The probes were found to show an accurate lysosome-targeting ability with high selectivity and high photostability under continuous excitation irradiation. The results show that these lysosome-targeted BODIPYs offer a simple and convenient tool for fluorescence imaging of lysosomes, which will be valuable for understanding the activity and function of lysosomes in related cells.

Summary Elastic fibers are present in a variety of tissues and are responsible for their resilience. Until now, no optical contrast agent in the near-infrared (NIR) wavelength range of 700–900 nm has been reported for the imaging of elastic fibers. Here, we report the discovery of a NIR zwitterionic elastin probe ElaNIR (elastin NIR) through fluorescent-image-based screening. The probe was successfully applied for in vitro , ex vivo , and in vivo imaging by various imaging modalities. Age-related elastin differences shown by in vivo fluorescent and photoacoustic imaging indicated that ElaNIR can be a potentially convenient tool for uncovering changes of elastin in live models.

NAD(P)H:quinone oxidoreductase-1 (NQO1) is attractive as a potential cancer biomarker because it is abnormally expressed in many solid tumors and is closely related to a variety of carcinogenic processes. Determining and evaluating the content/activity of NQO1 in tumors is of great significance for early cancer diagnosis and therapeutic effect evaluation. Enzyme-activated imaging probes with tailored properties, high selectivity and sensitivity, and high temporal and spatial resolution have become powerful tools for detecting and monitoring NQO1 activity. In this review, we aim to offer a rigorous but succinct overview of activatable imaging probes by reporting the significant progress made in accurately detecting and imaging NQO1 activity. The design strategies, mechanisms and applications of relevant probes are rationally analyzed and discussed. We also emphasized the potential challenges and prospects of NQO1-activated imaging probes to further advance the development of diagnosis and therapeutic methods for NQO1-related cancers.

The screening of highly toxic chemical vapor is critical for environmental monitoring and human health maintenance. Herein, we reported a chemosensor (AC-HPD) for rapid and specific detection of highly toxic oxalyl chloride vapor, which adopted anthracene carboxyimide as a fluorophore and 3-aminopropanol as the reaction site. Upon coupling of oxalyl chloride with NH and OH groups, AC-HPD exhibited remarkable colorimetric and ratiometric fluorescence dual-mode responses towards oxalyl chloride via the intramolecular charge transfer effect. AC-HPD could determine oxalyl chloride with features of rapid response, excellent specificity, low detection limit (95 nM), as well as obvious color and fluorescence change. Furthermore, AC-HPD-embedded test strip was successfully fabricated and used as a flexible sensing device for rapid, sensitive and visible monitoring oxalyl chloride vapor.

Sulfur dioxide (SO2) can be endogenously produced by enzymes in mitochondria during oxidation of H2S or sulphur-containing amino acids, and plays important roles in several physiological processes. However, the design and synthesis of fluorescent probes which can detect mitochondrial SO2 and its derivatives in living cells still remain unresolved. Herein, we report the preparation of a lipophilic cationic dye 1 (Mito-Ratio-SO2), which targets the mitochondria in living cells and is sensitive to the presence of SO2 derivatives. The ratiometric probe Mito-Ratio-SO2 displays a 170 nm blue-shift in emission with two well-resolved emission bands upon addition of sulfite. Mechanistic studies indicate that three probe-SO2 adducts coexist after reaction, as supported by liquid chromatography and density function theory investigations. Importantly, the ratiometric probe is highly selective for sulfite over other bio-species including H2S. Fluorescence co-localization studies indicate that the probe localizes solely in the mitochondria of HeLa cells. Last but not least, fluorescent imaging of HeLa cells successfully demonstrates the detection of intrinsically generated intracellular SO2 derivatives in living cells.

Cyclic and acyclic ferrocene derivatives bearing two imidazolium rings have been synthesized and characterized by NMR, elemental analysis, mass spectra, and X-ray crystallography. Electrochemical measurements revealed that all the receptors displayed a significant anodic shift response for F−. In addition, for receptors 1, 2, and 4, addition of HSO4− induced quite different electrochemical behavior with dramatic cathodic peak current increase on CV. 1H NMR titrations demonstrated that receptors 1, 2, and 4 showed selectivity for AcO− while receptor 3 exhibited high affinity toward Cl− among the anions investigated.