Polysiloxane-Based Molecular Logic Gate for Dual-Channel Visualizing Mitochondrial pH and Sulphite Changes during Cuproptosis

Intracellular Cu-induced regulated cell death, characterized by the aggregation of lipidizing mitochondrial enzymes, is called cuproptosis. Mitochondria play a vital role in the metabolic regulation of cell injury and stressful immune responses. The pH levels and sulfur dioxide (SO2) content in mitochondria have important indicative roles in the regulation of cuproptosis. However, fluorescent probes that simultaneously detect changes in pH and SO2 in mitochondria during cuprotosis have not been reported. To fill this blank, in this study, we dexterously used functional polysiloxane as a fluorescent platform to propose a molecular logic gate probe P0-pH-SO2 for detecting changes in intramitochondrial pH and SO2 content through a dual-channel mode. In addition, we defined a new function to reflect the cellular state of the elesclomol-induced cuproptosis process based on the input and output of the relevant logic relationship. This new fluorescent molecular logic gate probe P0-pH-SO2 can be rapidly activated by mitochondrial sulfites to induce green fluorescence, while the red fluorescence is quenched with the proton in the mitochondria. Overall, this study developed a novel logic-gated molecular probe that provided a versatile strategy for monitoring the role played by intramitochondrial sulfites and H+ in cuproptosis. This work will open the way to broaden the applications of molecular logic gates and fluorescent polysiloxanes.

A bis-chalcone based colorimetric probe for the selective detection of bisulfite/sulfite anions: exploring surfactant promoted Michael addition of anions to α, β-unsaturated ketones

A probe, (1E,4E)-1,5-di(thiophen-2-yl)penta-1,4-dien-3-one, was developed for rapid, colorimetric, and selective detection of bisulfite/sulfite anions in aqueous solutions. This probe is based on the Michael addition reaction which is favoured in the presence of cationic micellar medium CTAB. CTAB promoted Michael addition is an effective tool to determine SO₂ toxicity, which is mainly expressed in terms of collective concentration of bisulfite and sulfite anions. The probe showed high selectivity and sensitivity toward bisulfite and sulfite over other interfering anions, with a detection limit of 0.43 μM and 0.23 μM, respectively. The possible recognition mechanism of the probe and the analyte was illustrated by NMR, HR-MS, IR, and computational analysis. Moreover, this probe showed great potential for the detection of bisulfite/sulfite in real samples, such as crystal sugar and brown sugar.

Small-Molecule Fluorescent Probe for Detection of Sulfite

Sulfite is widely used as an antioxidant additive and preservative in food and beverages. Abnormal levels of sulfite in the body is related to a variety of diseases. There are strict rules for sulfite intake. Therefore, to monitor the sulfite level in physiological and pathological events, there is in urgent need to develop a rapid, accurate, sensitive, and non-invasive approach, which can also be of great significance for the improvement of the corresponding clinical diagnosis. With the development of fluorescent probes, many advantages of fluorescent probes for sulfite detection, such as real time imaging, simple operation, economy, fast response, non-invasive, and so on, have been gradually highlighted. In this review, we enumerated almost all the sulfite fluorescent probes over nearly a decade and summarized their respective characteristics, in order to provide a unified platform for their standardized evaluation. Meanwhile, we tried to systematically review the research progress of sulfite small-molecule fluorescent probes. Logically, we focused on the structures, reaction mechanisms, and applications of sulfite fluorescent probes. We hope that this review will be helpful for the investigators who are interested in sulfite-associated biological procedures.

Fluorescent-based nanosensors for selective detection of a wide range of biological macromolecules: A comprehensive review

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nanobiosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharmaceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence technology, material chemistry, coordination polymers, and related research areas.

Synthesis and Properties of a Water-soluble Fluorescent Probe Based on ICT System for Detection of Ultra-trace SO2 Derivatives

SO2 and its derivatives are widely present in the environment and living organisms, endangering the environment and human health. Therefore, it is of great significance for the effective detection of sulfur dioxide (SO2) and its hydrated derivatives (HSO3- /SO32-). In this study, based on the mechanism of intramolecular charge transfer (ICT), a water-soluble colorimetric fluorescent probe (E)-2-(4-acetamidostyryl)-3-(5-carboxypentyl)-1, 1-dimethyl-1H-benzo[e]indol-3-ium (ABI) for the detection of SO2 derivatives was successfully synthesized from p-acetaminobenzaldehyde by connecting the benzo[e]indoles cationic fluorophore containing highly activated methyl via C = C double bond, and the ABI structure was characterized by HRMS and 1H NMR, 13 C NMR. Studies have shown that the ABI probe has some advantages such as good selectivity for SO2 derivatives, high sensitivity (detection limit LOD = 14.9 nM), and fast reaction rate. After adding HSO3-, the color of the probe solution changed from light yellow to colorless within 10 s, which provides a simple way to identify bisulfite with the naked eye. Studies on the effect of pH on the fluorescence performance of ABI showed that fluorescence performance of ABI was stable in the range of pH (7.0-10.26). Therefore, ABI is expected to become an effective tool for detecting SO2 derivatives in cells and organisms in the future.

Biological applications of a turn-on bioluminescent probe for monitoring sulfite oxidase deficiency in vivo

Sulfites are widely used as preservative and antioxidant additives in food and drug. A non-invasive method for in vivo imaging of sulfite represents a powerful tool for estimating its potential effects in living organisms. Herein, we report the design, development, and application of sulfite bioluminescent probes (SBPs) for the analyte-specific detection of sulfite through sulfite-mediated intramolecular cleavage. Among them, SBP-1 exhibited the excellent responsivity, high selectivity and sensitivity. By taking advantage of this probe, the first in vivo imaging of sulfate was successfully carried out, not only to trace exogenous sulfite level in living animal, but also to investigate endogenous sulfite in a sulfite oxidase deficiency model.

A double-indole structure fluorescent probe for monitoring sulfur dioxide derivatives with distinct ratiometric fluorescence signals in mammalian cells

Based on the addition reaction of the sulfur dioxide derivative to the CC double bond, the probe HDI was designed and synthesized. The two-channel fluorescent probe HDI changed from orange to colorless and the fluorescence changed from red to blue when the bisulfite was detected. And the probe responds rapidly to bisulfite within 2 min, with high sensitivity and specificity. In addition, the probe can be used to detect the concentration of bisulfite with a low detection limit (80 nM). Cytological experiments have also demonstrated that probe HDI has low cytotoxicity and could be used for ratiometric detection of sulfur dioxide derivatives in living cells.

A novel ratiometric fluorescent probe for selective detection of bisulfite in living cells

In this work, a new type of ratiometric fluorescent probe APCT for bisulfite anion based on Michael-type addition reaction was designed.

A simple but effective fluorescent probe for the detection of bisulfite

A simple but effective fluoresecent probe for the detection of bisulfite based on Michael addition reaction.

A mitochondria-targeted fluorescent probe for ratiometric detection of endogenous sulfur dioxide derivatives in cancer cells

A new mitochondria-targeted fluorescent probe HCy-D, constructed by dansyl and hemicyanine fluorophores, for SO₂derivatives (HSO₃⁻/SO₃²⁻) was presented.

A highly sensitive and selective turn-on fluorescent probe for sulfite and its application in biological imaging

A new fluorescein-based probe (1) has been developed for the highly sensitive and selective detection of sulfite.