Ratiometric Fluorescence Response Research Articles

Highly Selective Ratiometric Sensors for Pb2+ Based on Luminescent Zn(II)-Coordination Polymers with Thiophenedicarboxylate. Crystal Structures and Spectroscopic Studies.

The development of luminescent coordination polymers for the selective sensing of Pb2+ in water constitutes an active area of research that impacts analytical, environmental, and inorganic chemistry. Herein, two novel water-stable 2D Zn-coordination polymers {[Zn2(H2O)2(tdc)2(bpy)]·(H2O)}n 1 and [Zn(tdc)(tmb)]n 2 (tdc = thiophenedicarboxylate; bpy = 4,4'-bipyridine and tmb = 4,4'-trimethylenebipyridine) were synthesized, structurally determined by single crystal X-ray diffraction, and studied in-depth as luminescent sensors for a series of cations (Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ Cd2+, Hg2+ and Pb2+) in 20% aqueous ethanol. These Zn-polymers possess photostability in 20% aqueous ethanol with a strong emission at 410 upon excitation at 330nm and quantum yields of around Φ = 0.09. Under these conditions, Pb+2 can be efficiently sensed with polymer 2 through a fluorescent ratiometric response with selectivity over common interfering metal ions such as Cu2+, Cd2+ and Hg2+ in the micromolar concentration range (detection limit = 1.78 ± 10μM). Such selectivity/affinity of Pb2+ over Hg2+ for luminescent chemosensors is still rare. On the basis of spectroscopic tools (1H NMR, far ATR-IR, PXRD), the X-ray crystal structure of 2, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopic analysis, the ratiometric fluorescent response is proposed via an efficient metal-ion exchange driven through interactions between thiophenedicarboxylate rings and Pb2+ ions. The use of flexible luminescent Zn-coordination polymers as sensors for selective and direct detection of Pb2+ in aqueous media has been unexplored until now.

On-Site Quantitative Visualization of Singlet Oxygen in Crops via an Organic Small Molecule-Based Ratiometric Fluorescent Probe and a Mobile Fluorescence Analysis Device.

Singlet oxygen (1O2) plays imperative roles in a variety of biotic or abiotic stresses in crops. The change of its concentration within a crop is closely related to the crop growth and development. Accordingly, there is an urgent need to develop an efficient analytical method for on-site quantitative detection of 1O2 in crops. Here, we judiciously constructed a novel ratiometric fluorescent probe, SX-2, for the detection of 1O2 in crops. Upon treating with 1O2, probe SX-2 displayed highly selective ratiometric fluorescence response, which is favorable for the quantitative detection of 1O2. Concurrently, the fluorescence solution color of probe SX-2 was varied, obviously from blue to yellow, indicating that the probe is beneficial for on-site detection by the naked eye. Sensing reaction mechanism studies showed that the 2,3-diphenyl imidazole group in SX-2 could function as a new selective recognition group for 1O2. Probe SX-2 was utilized for the detection of photoirradiation-induced 1O2 and endogenous 1O2 in living cells. The changes in the 1O2 level in zebrafish were also tracked by fluorescence imaging. In addition, the production of 1O2 in crop leaves under a light source of different wavelengths was studied. The results demonstrated more 1O2 were produced under a light source of 365 nm. Furthermore, to achieve on-site quantitative detection, a mobile fluorescence analysis device has been made. Probe SX-2 and mobile fluorescence analysis device were capable of on-site quantitative detecting of 1O2 in crops. The method developed herein will be convenient for the on-site quantitative measurement of 1O2 in distinct crops.

New Mn-CP as a multi-responsive fluorescent probe for ratiometric sensing toward ascorbic acid and turn-off sensing toward nitrofurazone and acetylacetone

The abuse of environmental and biological related molecules, such as small biomolecules, pharmaceutical antibiotics and volatile organic chemicals has become a hotspot issue of global concern. Thus, exploring accurate and effective techniques for monitoring these species remains a major challenge. Here, by employing semi-rigid tetracarboxylate ligand H4edda, one new 2D Mn-based coordination polymer with formula of [Mn2(edda)(phen)2(H2O)2]n (Mn-CP; H4edda = 5,5′-(ethane-1,2-diylbis(oxy)) diisophthalic acid); phen = 1,10-phenanthroline) has been hydrothermally fabricated. The prepared Mn-CP possesses a sql topology with Schläfli symbol of (44·62). Stability research for Mn-CP reveals that it maintains structural stability and initial fluorescence intensity after soaking in water for one week. Moreover, Mn-CP also displays high structural stability in acidic-basic aqueous solution of broad pH scope (1–13) for 48 h. Importantly, photoluminescence measurements indicate that it shows ratiometric fluorescence response to ascorbic acid (AA) as well as turn-off response toward nitrofurazone (NFZ) and acetylacetone (ACAC). The developed fluorescence probe based on Mn-CP shows merits of high selectivity and low detection limits (33.67 nM, 1.43 nM and 2.29 μM for AA, NFZ and ACAC, respectively). The possible mechanisms have been thoroughly explored through exhaustive experimental surveys and theories calculations. The CP-based multi-responsive fluorescent probe designed in this work extends the application of such materials in environmental and biological related fields.

An experimental and theoretical study on mechanistic insights into urolithin-based ratiometric fluorescent probe for instant quantitative detection of fluoride ions

Fluoride detection has been playing an important role in chemical, biological, and medicinal field, especially for keeping physical health and resisting environmental pollution. Herein, a urolithin B fluorescent probe has been successfully developed with good sensitivity, selectivity, anti-interference ability. The low limit of detection (LOD) refers to 0.156 μM, and the instant response time to F− is less than 1 s. The probe is suitable for quantitatively and qualitatively ratiometric detection for F− in solution with two distinct emission bands at 425 (blue) and 566 nm (orange), with the coordinate change of CIE from (0.38, 0.41) to (0.22, 0.11). Urolithin B displayed a remarkable ratiometric fluorescence response towards F−. The detection mechanistic was further proposed by NMR and electronic spectroscopic experiments combining with time-dependent density functional theoretical calculation.

Rapid and reliable ratiometric fluorescence detection of isoquercitrin based on a high-nuclearity Zn(II)-Nd(III) nanomolecular sensor

Rapid and quantitative detection of isoquercitrin (Isq) has been attracting much attention due to its outstanding pharmacological and physiological activities. Herein, an interesting 48-metal Zn(II)-Nd(III) nanocluster (1, molecular sizes 1.3 × 2.8 × 3.1 nm) with salen-type Schiff base ligand was constructed as molecular sensor for the luminescence detection of Isq. 1 exhibits visible ligand-centered emission and NIR luminescence of Nd(III), and shows ratiometric fluorescence response to Isq with high sensitivity even in the presence of other interferences. The fluorescence sensing behavior can be expressed by a second-order equation I1060nm/I480nm = A*[Isq]2 + B*[Isq] + C, which is used to quantitatively analyze the Isq concentrations in DMF and FCS. The LODs to Isq for the ligand-centered and lanthanide emissions of 1 in DMF are 0.21 μM and 0.11 nM, respectively. The quenching of the ligand-centered emission of 1 caused by Isq is attributed to the competitive absorption of light energy and “inner effect”, while, the luminescence enhancement is due to the “antenna effect”.

Ratiometric Fluorescence Detection of Levofloxacin Based on a Cube-like Zn(II)-Eu(III) Nanocluster: Functionalized Sodium Alginate Film for the Detection in Serum and Medicine.

A cube-like Zn(II)-Eu(III) nanocluster 1 (molecular sizes: 1.8 × 2.0 × 2.0 nm) was constructed by the use of a new long-chain Schiff base ligand. It shows a ratiometric fluorescence response to levofloxacin (LFX) with high sensitivity and selectivity, which can be expressed as I615nm/I550nm = A*[LFX]2 + B*[LFX] + C. It is used to quantitatively detect the LFX concentrations in fetal calf serum (FCS) and tablets sold in pharmacy. Filter paper strips bearing 1 can be used to qualitatively detect LFX by a color change to red under a UV lamp. 1 and its hybrid with sodium alginate (SA), 1@SA, display potential applications in the qualitative detection of LFX in FCS and the medicine. The limit of detection of 1 to LFX is as low as 2.1 × 10-2 nM.

Bifunctional ratiometric fluorescent membrane containing pyrene-based probe for visual monitoring and efficient removal of Al3+

A bifunctional fluorescent pyrene-based probe, PYR, was designed by incorporating pyridine and phenolic hydroxyl moieties into pyrene fluorophore, which exhibited ratiometric fluorescent response toward Al3+. PYR underwent unique monomer-excimer conversion in ratiometric manner through the formation of a 2:1 coordination complex and accomplished with fluorescent color variation from green to blue. PYR displayed excellent selectivity, high sensitivity (LOD = 0.33 μM), rapid response (<45 s), and good cytocompatibility to Al3+. Notably, a fluorescent cellulose membrane decorated with PYR was successfully developed and applied for accurately quantify of Al3+ in diverse actual samples, and high-efficiency removal (∼96%) of Al3+ from water systems, with sustainable recycling performance up to 10 times. Bifunctional membranes also played an important role in reducing the LOD of Al3+ to 16 nM through the preconcentration process. Therefore, this study is crucial to the development of environmentally sustainable strategy for monitoring and removing pollution.

Ratiometric peptide-based fluorescent probe with large Stokes shift for detection of Hg2+ and S2− and its applications in cells imaging and smartphone-assisted recognition

In this work, a new ratiometric fluorescent probe DKA was synthesized based on the double sides of lysine backbone conjugated with alanine and dansyl groups. DKA exhibited fluorescence ratiometric response for Hg2+ with high sensitivity (13.4 nM), specific selectivity (only Hg2+), strong anti-interference ability (no interference), fast recognition (within 60 s) and wide pH range (5–10). The stoichiometry of binding of DKA and Hg2+ was determined to be 1:1 via Job’s plot, ESI-HRMS and 1HNMR titration analysis. Subsequently, the in situ formation of DKA-Hg2+ complex was used for highly selective detection of S2− as a novel fluorescence “on–off” probe, and the lowest detection limit for S2− was 12.9 nM. In addition, DKA possessed excellent cells permeation and low toxicity, and fluorescence imaging of Hg2+ and S2− was performed in living Hacat cells. Most importantly, the digital imaging using a smartphone color recognition APP indicated that DKA could semi-quantitatively and visually detected Hg2+ and S2− without expensive equipment.

Portable ratiometric fluorescence detection of Cu2+and thiram.

Food contaminants pose a danger to human health, but rapid, sensitive and reliable food safety detection methods can offer a solution to this problem. In this study, an optical fiber ratiometric fluorescence sensing system based on carbon dots (CDs) and o-phenylenediamine (OPD) was constructed. The ratiometric fluorescence response of Cu2+and thiram was carried out by the fluorescence resonance energy transfer (FRET) between CDs and 2,3-diaminophenazine (ox-OPD, oxidized state o-phenylenediamine). The oxidation of OPD by Cu2+resulted in the formation of ox-OPD, which quenched the fluorescence of CDs and exhibited a new emission peak at 573 nm. The formation of a [dithiocarbamate-Cu2+] (DTC-Cu2+) complex by reacting thiram with Cu2+, inhibits the OPD oxidation reaction triggered by Cu2+, thus turning off the fluorescence signal of OPD-Cu2+. The as-established detection system presented excellent sensitivity and selectivity for the detection of Cu2+and thiram in the ranges of 1 ∼ 100μM and 5 ∼ 50μM, respectively. The lowest detection limits were 0.392μM for Cu2+and 0.522μM for thiram. Furthermore, actual sample analysis indicated that the sensor had the potential for Cu2+and thiram assays in real sample analysis.

A disaggregation-driven BODPIY-based probe for ratiometric detection of G4 DNA

In conventional systems, fluorescent probes with planar structures usually experience the phenomenon of aggregation-induced quenching (ACQ) that limits their practical applications in bio-medical sensing. To confront such problem, an attractive way is to develop a disaggregation-induced emission (DIE) sensing strategy, where the quenched fluorescence is recovered via a disaggregation process. Currently most of the fluorescent probes designed based on DIE mechanism are signal off-on type with the fluorescent intensity changed at a single wavelength. On the other hand, ratiometric fluorescent probes have the advantage of having two distinct emission wavelengths, effectively avoiding environmental interference. The DIE probes with a ratiometric fluorescence response still poorly established. Herein, we report a BODIPY-based probe BODPA, where a 2,2′-dipicolylamine group was introduced to the meso-position of BODIPY core, for the selective ratiometric detection of G-quadruplex (G4) DNA. This probe in buffer solution formed aggregates with weak fluorescence at 508 nm. In the presence of G4 DNA, bright fluorescence was emitted at 518 nm through DIE mechanism. Taking advantage of the ratiometric manner, probe BODPA exhibited selectivity for G4 DNA over duplex DNA. The binding details between probe BODPA and G4 DNA were assessed by spectroscopic and molecular modeling methods, which suggested the ability of this probe could coordinate with G4 structure via end stacking and partial groove binding mode.

Monitoring Hg2+ ions in food and environmental matrices using a novel ratiometric NIR fluorescent sensor via carbonothioate-deprotection reaction

Mercury toxicity and its environmental impact are significant concerns for public health and environmental protection. Therefore, the development of effective, rapid, and reliable detection methods for trace levels of Hg2+ is crucial. Herein, a cyanine dye bearing a carbonothioate group is reported as a potential NIR fluorescent probe for Hg2+ detection. The spectral properties of the free probe have been characterized by the presence and absence of a series of analytes. The addition of Hg2+ leads to significant changes in the fluorescence signal with distinct red coloration compared to other competing analytes, indicating that the probe is highly selective for Hg2+. The fluorescence quantum yield increases from 0.073 to 0.315. The detection limit is 0.10 μM, indicating the high sensitivity of the probe to low Hg2+ levels. The most prominent sensing features of the probe include NIR fluorescence, low cytotoxicity, ratiometric fluorescence response, and fast response compared to most of the currently available fluorescent probes. In addition, the probe can detect Hg2+ in actual samples such as foodstuff, soil, water, and live cells. Bioimaging studies have demonstrated that the present probe is highly efficient in targeting mitochondria and possesses good imaging abilities for detecting Hg2+ in cells. Therefore, these results suggest that it can be proposed as a powerful NIR fluorescent probe for the highly sensitive detection of Hg2+.

Reversible Dual Fluorescence-Lifetime Imaging of Mitochondrial GSH and Microviscosity: Real-Time Evaluation of Ferroptosis Status.

Ferroptosis, as a new form of regulated cell death, is implicated in various physiological and pathological processes. Developing a single probe for an independent analysis of multiple analytes related to ferroptosis can provide more accurate information and simplify the detection procedures, but it faces great challenges. In this work, we develop a fluorescent probe for the simultaneous detection of GSH through ratiometric fluorescence response and microviscosity via a fluorescence lifetime model. Based on the reversible Michael addition reaction between GSH and unsaturated C═C bond, the probe responds reversibly to GSH with a ratiometric fluorescence variation and a fast response time (t1/2 = 4.7 s). At the same time, the probe is sensitive to environmental viscosity by changing its fluorescence lifetimes. The probe was applied to monitor the drug-induced ferroptosis process through both the classical Xc-/GSH/GPX4- and DHODH-mediated defense mechanisms. We hope that the probe will provide a useful molecular tool for the real-time live-cell imaging of GSH dynamics, which is benefit to unveiling related physiological and pathological processes.

Ratiometic fluorescent detection of Au(III) and fluorescent “turn-off” identification of Cu(II)/Hg(II) with a coumarin-based probe

A coumarin-based fluorescent probe CHA functionalized with a 2-hydrazone pyridine unit displayed different photophysical responses to Au3+, Cu2+ and Hg2+. It exhibited ratiometric fluorescent response to Au3+, whereas remarkable fluorescence “turn-off” response to Cu2+/Hg2+ in aqueous solution. Au3+ and Cu2+ respectively induced clear blue-shift and red-shift in the absorption maximum, while Hg2+ had little impact on the absorption spectrum. The results of NMR, Job's titration and competition assay reveal that CHA was hydrolyzed to aldehyde under catalysis of Au3+, while it formed complex with Cu2+ and Hg2+. The ratio of fluorescence intensities I490/I540 of CHA exhibited linear relationship to Au3+ concentration in the range of 0.5–5.0 μM with a detection limit of 0.02 μM. The fluorescence intensity at 540 nm was in linearly correlative with Cu2+/Hg2+ concentration. Therefore, CHA could be used for detection of Au3+, Cu2+/Hg2+ in different channels as well as visual differentiation of exogenous Au3+ and Cu2+/Hg2+ in living HeLa cells.

An efficient phenanthroimidazole-based luminogen for specific and selective detection of sarin gas surrogate, diethylchlorophosphate

The nerve agent's extreme toxicity makes it a prominent target to detect them to save global harmony. In the present contribution, we have introduced a phenanthroimidazole-based luminogen, BIB, for specific and selective detection of sarin gas surrogate diethylchlorophosphate (DCP) within the stores of various analogous toxic analytes. BIB displayed a highly distinct ratiometric fluorescence response toward detecting toxic sarin gas, mimicking DCP among all the other guest analytes showing a fluorogenic color change from blue to bluish-green color fluorescence under the exposure of a 365 nm UV lamp irradiation, which is wholly reversed due to the introduction of triethylamine (TEA). The reversibility is prominent in both the liquid and vapor states of DCP. Our probe BIB can selectively detect DCP with a low detection limit to µM range and superior to many available literatures. BIB's reversible and ratiometric response for detecting DCP provides a potential application as a portable and displayable photonic sensing tool for on-site detection. The successful demonstrations of BIB for practical application in detecting sarin gas encourage the researcher to explore the probable applications of imidazole-based luminogen as a photonic sensing device for recognizing various target analytes.

Albumin Hydrogel-Coated Mesoporous Silica Nanoparticle as a Carrier of Cationic Porphyrin and Ratiometric Fluorescence pH Sensor.

Here, we report that a mesoporous silica nanoparticle (MSN) coated with a fluoresceine-labeled bovine serum albumin (F-BSA) hydrogel layer works as a temperature-responsive nanocarrier for tetrakis-N-methylpyridyl porphyrin (TMPyP) and as a fluorescence ratiometric pH probe. F-BSA hydrogel-coated MSN containing TMPyP (F-BSA/MSN/TMPyP) was synthesized by thermal gelation of denatured F-BSA on the external surface of MSN. The F-BSA hydrogel layer was composed of an inner hard corona layer and an outer soft layer and was stable under physiological conditions. F-BSA/MSN/TMPyP exhibited temperature-dependent exponential release of TMPyP. In this release profile, the MSN was found to be a suitable host for stable encapsulation of tetracationic TMPyP by electrostatic interactions, and the F-BSA hydrogel layer mediated the diffusion of TMPyP from the MSN pore interior into the solution phase. Increasing temperature promoted partitioning of TMPyP from the pore interior to the F-BSA hydrogel layer, from where it was spontaneously released into the bulk solution phase by cation exchange. F-BSA/MSN/TMPyP also gave a linear ratiometric fluorescence response (1.3 per pH unit) in the pH range from 6.1 to 8.9.

Colorimetric and ratiometric fluorescent chemodosimeter for the detection of hydrazine via the Ing-Manske reaction in solution as well as in the gaseous state: An experimental and computational investigation

A new and simple fluoranthene-phthalimide conjugate (FP) was synthesized, and employed as a highly efficient hydrazine chemodosimeter in organo-aqueous solution. Based on the Ing-Manske reaction, the chemodosimeter FP showed a fast colorimetric and ratiometric fluorescent response for hydrazine with high sensitivity and selectivity over other competing analytes. The chemodosimeters detection limit for N2H4 was estimated to be 4.27 µM. Theoretical calculations were also executed to validate the experimental findings. Furthermore, the test strips and cotton swab made from the chemodosimeter FP are capable of enabling the quick and easy detection of N2H4 solution and vapour, respectively.

A chemodosimetric chemosensor for the ratiometric detection of nerve agent-mimic DCP in solution and vapor phases.

Nerve agents are among the most deadly and lethal chemical warfare agents (CWAs). Rapid identification is crucial for specialized individuals to take action against dangerous drugs. This paper describes the synthesis and characterisation of a probe (MNFZ) based on the methoxy naphthalene-furoic hydrazide group. The probe rapidly (100 s) detects and quantifies the nerve-agent simulant diethyl chlorophosphate (DCP) in both solution and vapor phases. This sensor uses a new recognition center, furoic hydrazide, where the nitrogen atom of the imine group (CN) attacks the electrophilic core phosphorus atom of DCP, followed by the hydrolysis of the imine group in the acetonitrile (ACN) solution to produce the corresponding aldehyde MNPA. The development of ICT character resulted in a distinct red-shifted ratiometric fluorescence response to DCP, with a very low limit of detection (12.2 nM). The probe is an efficient chemosensor due to its high selectivity over other organophosphorus compounds as well as its chemical stability across a wide pH range. DFT calculations, 1H NMR and HRMS were performed to finalize the sensing mechanism. Lastly, the as-designed sensor was successfully used to build a highly sensitive portable kit in test strips and a cotton biopolymer for simple and safe real-time monitoring of DCP.

A ratiometric fluorescent probe revealing the abnormality of acetylated tau by visualizing polarity in Alzheimer's disease.

Abnormal neuronal polarity leads to early deficits in Alzheimer's disease (AD) by affecting the function of axons. Precise and rapid evaluation of polarity changes is very important for the early prevention and diagnosis of AD. However, due to the limitations of existing detection methods, the mechanism related to how neuronal polarity changes in AD is unclear. Herein, we reported a ratiometric fluorescent probe characterized by neutral molecule to disclose the polarity changes in nerve cells and the brain of APP/PS1 mice. Cy7-K showed a sensitive and selective ratiometric fluorescence response to polarity. Remarkably, unlike conventional intramolecular charge transfer fluorescent probes, the fluorescence quantum yield of Cy7-K in highly polar solvents is higher than that in low polar solvents due to the transition of neutral quinones to aromatic zwitterions. Using the ratiometric fluorescence imaging, we found that beta-amyloid protein (Aβ) inhibits the expression of histone deacetylase 6, thereby increasing the amount of acetylated Tau protein (AC-Tau) and ultimately enhancing cell polarity. There was a high correlation between polarity and AC-Tau. Furthermore, Cy7-K penetrated the blood-brain barrier to image the polarity of different brain regions and confirmed that APP/PS1 mice had higher polarity than Wild-type mice. The probe Cy7-K will be a promising tool for assessing the progression of AD development by monitoring polarity.

A novel ratiometric tanshinone IIA-based fluorescent probe for sensitive and reversible detection of BF3 in solution and gaseous phase

Boron trifluoride (BF3) is extensively used in multiple industrial fields including semiconductor, battery and chemical industries. However, BF3 is also an extremely poisonous and caustic substance causing potential risk to environmental safety and human health. In this work, a novel ratiometric fluorescent probe (TBS) for sensing BF3 was designed and synthesized based on the natural phenanthraquinone tanshinone IIA. TBS exhibited a significant ratiometric fluorescence response toward BF3 with low detection limit (98 nM), short response time (1 min), prominent selectivity, anti-interference ability and reversibility. In addition, the sensing mechanism of TBS was investigated through 1H NMR titration, HRMS and DFT study. Furthermore, TBS was successfully utilized in quantitatively detecting BF3 concentrations of the commercially available BF3 reagent solutions as well as visually tracking gaseous BF3 through the TBS-loaded paper test strips.

A ratiometric fluorescent probe based on the FRET platform for the detection of sulfur dioxide derivatives and viscosity

BackgroundSulfur dioxide (SO2) is a common gaseous pollutant that significantly threatens environmental pollution and human health. Meanwhile, viscosity is an essential parameter of the intracellular microenvironment, manipulating many physiological roles such as nutrient transport, metabolism, signaling regulation and apoptosis. Currently, most of the fluorescent probes used for detecting SO2 derivatives and viscosity are single-emission probes or probes based on the ICT mechanism, which suffer from short emission wavelengths, small Stokes shifts or susceptibility to environmental background. Therefore, the development of powerful high-performance probes for real-time monitoring of sulfur dioxide derivatives and viscosity is of great significance for human health. ResultsIn this research, we designed the fluorescent probe QQC to detect SO2 derivatives and viscosity based on FRET platform with quinolinium salt as donor and quinolinium-carbazole as acceptor. QQC exhibited a ratiometric fluorescence response to SO2 with a low detection limit (0.09 μM), large Stokes shift (186 nm) and high energy transfer efficiency (95 %), indicating that probe QQC had good sensitivity and specificity. In addition, QQC was sensitive to viscosity, with an 9.10-folds enhancement of orange fluorescence and an excellent linear relationship (R2 = 0.98) between the logarithm of fluorescence intensity at 592 nm and viscosity. Importantly, QQC could not only recognize SO2 derivatives in real water samples and food, but also detect viscosity changes caused by food thickeners and thereby had broad market application prospects. SignificanceWe have developed a ratiometric fluorescent probe based on the FRET platform for detecting sulfur dioxide derivatives and viscosity. QQC could not only successfully detect SO2 derivatives in food and water samples, but also be made into test strips for detecting HSO3−/SO32− solution. In addition, the probe was also used to detect viscosity changes caused by food thickeners. Therefore, this novel probe had significant value in food and environmental detection applications.