Fluorescence Turn-on Research Articles

Golgi-targeted fluorescent probe for nitric oxide imaging in Parkinson’s disease models

Nitric oxide (NO) regulates cell damage by neurotoxin and participates in neuronal cell death in Parkinson’s disease (PD). A large number of nitric oxide synthases involved in the synthesis of NO exists in the Golgi apparatus and hence, exploring the Golgi NO in PD is of great significance. Fluorescent probes provide powerful non-invasive detection and imaging tools in life systems. However, Golgi-targetable fluorescent probe has not yet been reported to detect and disclose the level changes of Golgi NO in PD. Herein, we report a Golgi-targetable turn-on fluorescence probe Gol-NO for the detection of Golgi NO, which shows low cytotoxicity, high sensitivity (about 1.6 nM of detection limit) and selectivity, and rapid response (<1 min) for NO. Moreover, we show that it can detect not only endogenous and exogenous NO in cells and zebrafish but also the level changes of NO in the rotenone-induced cell and zebrafish PD models, indicating that Gol-NO is a valuable new tool to explore NO in Golgi and study PD.

A vapofluorochromic dimethylaniline naphthol Schiff base used for fabricating smart textiles for VOCs detection

This work presents the synthesis and photophysical properties of a vapoluminescent compound, (E)-1-(((4-(dimethylamino)phenyl)imino)methyl)naphthalen-2-ol (DPINO), and further studies its photophysical properties, mainly including twisted intramolecular charge transfer (TICT) and vapoluminescent behaviors. DPINO emits wreak fluorescence deposited on cellulose substrate, but exhibits a turn-on effect in response to various kinds of VOCs, showing fast response and high visual identification. Through spectral analysis, it is found that the physical interaction between DPINO and VOCs is influenced by multiple factors, including volatility, structural similarity and molecular size (steric hindrance), leading to varying degrees of fluorescence response toward different VOCs. Using RGB (red-green-blue) and CIE L*a*b* (CIELAB) color spaces, the output signals are well-quantified, deriving color shift (ΔE*) for sensitivity evaluation. And the limit of detection (LOD) is calculated to be 7.4 mg/m3 (2.22 ppm) and 2.4 mg/m3 (0.72 ppm), based on RGB and CIE L*a*b*, respectively. We further fabricated a bimolecular smart textile by dip-dyeing method, which includes the present DPINO as well as an inert luminogen MMA, i.e., fluorescent reference. The DPINO-MMA bimolecular smart textile can be freely designed in shape and size, and further made into smart clothes labels, e.g., chest card, arm band and wrist band. In scenario-based experiments, the smart textile shows notable turn-on fluorescence in response to VOCs, enabling high visual identification and real-time feedback.

Nanomolar detection of hypochlorite in ground water samples by a norbornene-based polymeric sensor via unusual fluorescence turn-on response

Hypochlorite anion has been widely used as a bleaching and disinfecting agent in daily life. Selective and sensitive identification ofOCl-ions from water is very important for researchers. For this purpose, monomeric (NPh), and polymeric (PNPh-Peg) novel fluorescent sensors have been established for the specific and excellently unique sensors that exhibit selective characteristics like excellent resistance to bleaching and a high fluorescence brightness. A multi-functional random polymer (PNPh-Peg) with ICT (intramolecular charge transfer) active para–amino phenol functionality and reactive oxygen species (ROS) responsive, PEG attached are readily prepared via ROMP (ring-opening metathesis polymerization).: An ICT-active random polymer (PNPh-Peg) exhibited an unexpectedly strong cyan blue emission in a water medium compared to that in other common organic solvents, which was dramatically increased by adding a trace amount of NaOCl.: Incorporating PEG moiety in the polymeric backbone increases the water solubility of a copolymer, and the ROS-responsive groups make the polymer a good ROS scavenger. Upon oxidation of the phenol group into carbonyl, both the monomeric (NPh) and polymeric (Norp-PEG oh) sensors showed a selective, noticeable, unusual fluorescence turn-on response towardsanalyteOCl-ions with a very fast response (within three minutes). The detection limit (59.14 nM) and (126.93 nM) were calculated for monomeric and polymeric sensors, respectively. This was a selective, specific oxidation reaction of the completely water-soluble random polymeric sensor (PNPh-Peg) for hypochlorite anions and can be applicable for quantitative measurement of aqueous OCl-. This ICT-active random polymeric molecule (PNPh-Peg) can also be used as a fluorescent sensor for unique OCl- detection from contaminated water by preparing a sensor-coated paper strip. Thus, these multi-functional monomeric (NPh) and polymeric (PNPh-Peg) sensors are anticipated to apply to the environment.

Zinc-Induced Fluorescence Turn-On in Native and Mutant Phycoerythrobilin-Binding Orange Fluorescent Proteins.

Cyanobacteriochrome (CBCR)-derived fluorescent proteins are a class of reporters that can bind bilin cofactors and fluoresce across the ultraviolet to the near-infrared spectrum. Derived from phytochrome-related photoreceptor proteins in cyanobacteria, many of these proteins use a single small GAF domain to autocatalytically bind a bilin and fluoresce. The second GAF domain of All1280 (All1280g2) from Nostoc sp. PCC7120 is a DXCF motif-containing protein that exhibits blue-light-responsive photochemistry when bound to its native cofactor, phycocyanobilin. All1280g2 can also bind non-photoswitching phycoerythrobilin (PEB), resulting in a highly fluorescent protein. Given the small size, high quantum yield, and that unlike green fluorescent proteins, bilin-binding proteins can be used in anaerobic organisms, the orange fluorescent All1280g2-PEB protein is a promising platform for designing new genetically encoded metal ion sensors. Here, we show that All1280g2-PEB undergoes a ∼5-fold reversible zinc-induced fluorescence enhancement with a blue-shifted emission maximum (572 to 517 nm), which is not observed for a related PEB-bound GAF from Synechocystis sp. PCC6803 (Slr1393g3). Zn2+ significantly enhances All1280g2-PEB fluorescence across a biologically relevant pH range from 6.0 to 9.0, with pH-dependent dissociation constants from 1 μM to ∼20-80 nM. Site-directed mutants aiming to sterically decrease and increase access to PEB show a decreased and similar amount of zinc-induced fluorescence enhancement. Mutation of the cysteine residue within the DXCF motif to alanine abolishes the zinc-induced fluorescence enhancement. Collectively, these results support the presence of a unique fluorescence-enhancing Zn2+ binding site in All1280g2-PEB likely involving coordination to the bilin cofactor and requiring a nearby cysteine residue.

A coumarin-based multifunctional chemosensor for Cu2+/Al3+ as an AD theranostic agent: Synthesis, X-ray single crystal analysis and activity study

The pathogenesis of Alzheimer's disease (AD) is complex. So far there is no effective drug to treat the disease. The pathological changes of AD began 30 years before symptoms, so early diagnosis is considered to be important for AD treatment. Integrating diagnosis and therapy into a single regent has provided a new opportunity for AD treatment. Given that metal dyshomeostasis is thought to be one of the key factors to cause AD, a Schiff base substituted coumarin (probe 1) has been designed and synthesized as a selective metal chelator for multi-factor anti-AD in this work. The results of metal ions recognition showed that probe 1 had high selective fluorescent turn-on response to Al3+ and fluorescent turn-off response to Cu2+, due to intramolecular charge transfer (ICT) mechanism. Meanwhile, the results of both in vitro and in vivo bioactivities evaluation including metal chelation, reactive oxide species (ROS) elimination, self-/Cu2+-induced Aβ aggregation showed that 1 and 1-Cu(II) complex had excellent synergistic anti-AD activities. In addition, 1 had low cytotoxicity and was predicted to cross the blood-brain barrier (BBB). Noticeably, X-ray single crystal diffraction of 1-Cu(II) provided molecular level information to explain the structure and theranostic activity relationship. To sum up, 1 may be a promising candidate for the development of AD theranostic agent.

Construction of a ratiometric fluorescent probe for discriminative detection of SO2 derivatives and Cys and its bio-imaging application

Endogenous sulfur dioxide (SO2) and cysteine (Cys) are important species and interacted with each other. However, due to the reactivity of these species, it is difficult to differentiated detection them. Thus, it is necessary to develop new fluorescent probe for discriminative detect these reactive sulfur species in biological environment. Herein, A new hemicyanine derivative Mito-AE with dual recognition sites for SO2 derivatives and Cys detection was constructed and applied in biological detection. Mito-AE exhibited ratiometric fluorescence change (F470/F610) of over 90-fold when interacted with SO2, and a dramatic fluorescence turn-on at 610 nm when interacted with Cys. The probe can monitor both SO2 derivatives and Cys with fast response rate (within 1 min), high sensitivity and selectivity. As proved by biological experiments, Mito-AE was able to successfully detect exogenous and endogenous SO2 in living cells as well as in mitochondria area. More importantly, the detection of SO2 derivatives and Cys in zebrafish model suggesting a potential application for studying the multiple interaction of biological sulfurous species in live organism.

A highly selective fluorescence turn-on sensor for Hg2+ based on quinolimide in aqueous media and its applications

Herein, a novel fluorescent sensor QPE based on quinolimide was developed, which displayed the highly selective response to Hg2+ through the turn-on signal in aqueous media. The corresponding recognition mechanism of QPE for Hg2+ was investigated by the titration experiments, Job’s plots, HRMS, and DFT calculations analysis. QPE could detect Hg2+ in a broad pH range (pH = 4–9) with the LOD of 20 nM and the LOQ of 66 nM. Meanwhile, QPE-loaded test strips were demonstrated in the visual detection of Hg2+. Importantly, QPE exhibited the reliable capability to track Hg2+ in real water and soil samples and yeast cells, indicating that QPE could be used as a prospective tool for monitoring Hg2+ in wide fields.

Design and synthesis of a hydrazinopthalazine derived chemosensor to detect metal ions Zn2+, Al3+ via CHEF effect with biological study and theoretical calculation

A multiple metal ion detector, H3L [H3L = 4-methyl-2,6-bis((E)-(2-(phthalazin-1-yl)hydrazono)methyl)phenol] has been synthesized upon mixing 2,6-diformyl-4-methylphenol (DFP) and hydrochloride salt of hydrazinopthalazine in 1:2 ratio. H3L successfully detects Zn2+ and Al3+ ions through fluorescence enhancement in HEPES buffer (1:9, MeOH:H2O, v/v, pH 7.4). The fluorescent probe and its metal-bound compounds (1 and 2) are characterized using different spectroscopy and mass spectrometric techniques. The turn-on fluorescence response towards Zn2+ and Al3+ was explained based on PET-OFF, and chelation enhanced fluorescence (CHEF) ON processes. The binding mode and sensing mechanism of compounds 1 and 2 were confirmed using DFT calculations. H3L exhibits low detection limits and strong binding constants towards Zn2+ (2.37 × 10−6 M and 3.49 × 104 M−1) and Al3+ (1.32 × 10−6 M and 2.67 × 104 M−1) ions. It is successfully used in paper strips for the detection of Zn2+ and Al3+. Biocompatible H3L also applied as a visual probe for the practical determination of Zn2+ and Al3+ on cervical cancer cells.

PH-Dependent Dual-Mode Detection toward Uranium by a Zinc-Tetraphenylethylene Fluorescent Metal-Organic Framework.

An interpenetrated tetraphenylethylene-based fluorescent metal-organic framework (ECUT-180) with exceptional sensitivity, excellent selectivity, and fast response (less than 30 s) toward uranium was successfully prepared. Especially, in the prescence of uranyl, ECUT-180 displays significant fluorescence turn-on under pH 2-3, while fluorescence turn-off under pH 4-8. The corresponding detection limits were determined to be 2.92 ppb at pH 2 and 0.86 ppb at pH 8, both of which are lower than the average uranium content (3.3 ppb) in seawater. Mechanism investigation reveals that the fluorescence enhancement on the strong acid condition can be assigned to uranium adsorption, while the quenching is caused by the resonance energy transfer.

Pyrene-Based Cationic Fluorophores with High Affinity for BF4-, PF6-, and ClO4- Anions: Detection and Removal.

Anions play an indispensable role in the balance and regulation of the ecological environment and human health; however, excess anions can cause serious ecological and environment problems. Therefore, the detection and removal of excess anions in aqueous solution is not only a technological problem but also crucial for environmental protection. Herein, a set of water-soluble pyrene-based cationic fluorophores were synthesized, which exhibit high sensitivity for the detection of the anions BF4-, PF6-, and ClO4- via electrostatic interactions. Such fluorescent probes exhibit "turn-on" emission characteristics even at low concentrations of anions due to anion-π+ interactions. Moreover, these fluorescence probes act as efficient precipitating agents for the removal of the BF4-, PF6-, and ClO4- anions from an aqueous environment. This work opens up new avenues for future research on pyrene-based fluorophores as turn-on fluorescence probes for anion detection and as excellent precipitating agents in environmental settings.

Alkaline phosphatase triggered gold nanoclusters turn-on fluorescence immunoassay for detection of Ochratoxin A

Ochratoxin A (OTA) is a highly toxic mycotoxin which can cause a variety of diseases. Sensitive detection of OTA is significant for food safety. Herein, a feasible and sensitive immunoassay was established for OTA detection by alkaline phosphatase (ALP) triggered gold nanoclusters (AuNCs) turn-on fluorescence. The fluorescence of the AuNCs can be quenched by Cr6+ induced aggregation of AuNCs and the fluorescence resonance energy transfer (FRET) between AuNCs and Cr6+. Under the catalytic action of ALP-labelled IgG (IgG-ALP), the ascorbic acid 2-phosphate (AA2P) was hydrolyzed to ascorbic acid (AA) for the reducing of Cr6+ to Cr3+. As a result, the degrees of AuNCs aggregation and FRET were weakened and the fluorescence of AuNCs was turned on. The amount of OTA in the sample was negatively correlated with the amount of IgG-ALP captured by anti-OTA monoclonal antibody (McAb) in the microplate. In optimal conditions, the turn-on fluorescence immunoassay had a good linear range of 6.25–100 ng/mL, and the detection limit was 0.693 ng/mL. The recoveries of OTA from corn were 95.89%-101.08% for the fluorescence immunoassay. This work provided a feasible, sensitive and good selectivity fluorescence method for OTA detection.

Current and Future of "Turn-On" Based Small-Molecule Copper Probes for Cuproptosis.

Increasing evidence shows that abnormal copper (Cu) metabolism is highly related to many diseases, such as Alzheimer's disease, Wilson's disease, hematological malignancies and Menkes disease. Very recently, cuproptosis, a Cu-dependent, programmed cell death was firstly described by Tsvetkov et al. in 2022. Their findings may provide a new perspective for the treatment of related diseases. However, the concrete mechanisms of these diseases, especially cuproptosis, remain completely unclear, the reason of which may be a lack of reliable tools to conduct highly selective, sensitive and high-resolution imaging of Cu in complex life systems. So far, numerous small-molecular fluorescent probes have been designed and utilized to explore the Cu signal pathway. Among them, fluorescence turn-on probes greatly enhance the resolution and accuracy of imaging and may be a promising tool for research of investigation into cuproptosis. This review summarizes the probes developed in the past decade which have the potential to study cuproptosis, focusing on the design strategies, luminescence mechanism and biological-imaging applications. Besides, we put forward some ideas concerning the design of next-generation probes for cuproptosis, aiming to tackle the main problems in this new field. Furthermore, the prospect of cuproptosis in the treatment of corresponding diseases is also highlighted.

Development of turn-on fluorescent sensor based on green emissive carnosine-modified tannic acid carbon dots for the selective detection of ascorbic acid

Ascorbic acid (AA) is an indispensable biological antioxidant with anti-aging potential in neurological disorders such as Parkinson’s and Alzheimer’s. Its abnormal concentrations in physiological fluids like human serum can lead to neurological complications. In this study, a turn-on fluorescent sensor was developed using dipeptide (i.e., carnosine) modification of the polyphenolic tannic acid (TA) carbon dots (CDs) (TATA-CDs) for AA detection. Blue-fluorescent TATA-CDs were synthesized using the hydrothermal treatment of the TA and ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) as a nitrogen (N) dopant. TATA-CDs were functionalized with carnosine (TATA-Car CDs) using a facile stirring reaction. Their morphological and optical properties were studied via TEM, XRD, UV–Vis, and fluorescence spectroscopy. TATA-Car CDs displayed green fluorescence with excitation and emission wavelength maxima of 400 and 509 nm, respectively. These novel CDs are responsible for the selective turn-on fluorescence sensing of AA (0 to 15 nM) when mixed with copper (Cu2+) ions and deliver a low detection limit of 1.34 nM. The practicality and feasibility of TATA-Car CDs were investigated in human serum samples. From this perspective, the proposed fluorescent sensor is more suitable for the real-time monitoring of AA in different neurological disorders.

Explorations of Fluorescence Modulation of DNA Functionalized Single Wall Carbon Nanotubes by Catechol-Bearing Compounds

This work describes explorations into analyte-mediated modulation of the fluorescence of single-stranded DNA functionalized single wall carbon nanotubes (SWCNT). SWCNTs have several photophysical properties that make them attractive for imaging in biology. They fluoresce in the near-infrared (NIR) region of the spectrum (900 – 1300 nm), which is suitable for imaging in thick biological specimens because of reduced scattering of NIR photons and minimal tissue autofluorescence. SWCNTs exhibit superior photostability and can be considered to be non-photobleaching on time scales of interest to biological imaging. In addition to these advantageous photophysical properties, SWCNT fluorescence can be selectively sensitized to local chemical environments, which has served as a basis for the synthesis and application of SWCNT-based optical biosensors for a variety of biologically relevant compounds including dopamine, norepinephrine, serotonin, and oxytocin, among others. However, the mechanistic basis for fluorescence modulation of functionalized nanotubes by various classes of analytes remains incompletely understood. One class of optical biosensors that have been particularly successful in biological research includes (GT)N oligonucleotide functionalized SWCNTs that exhibit exquisite turn-on response to compounds that contain catechol-like motifs. In this work, we offer new insights into the mechanism of molecular recognition and fluorescence modulation of this sensor class by catechol-like compounds. We first carried out a fragment-based structure activity relationship study to establish how the structural and electronic properties of these compounds correlated with their ability to modulate SWCNT-fluorescence. This helped us establish a spectrum of substrate functionalities that are detectable by this sensor class. Intriguingly however, our experiments revealed that solution phase fluorescence turn-on events are critically influenced by factors that are not intrinsic to the analytes, including solution pH. We will present the pH dependence of fluorescence turn-on events and establish structural and electronic correlates for these dependencies. As a results of these explorations, we have been able to achieve an improved understanding of sensor dynamics and sensing mechanism. We expect that the insights gleaned from this work will contribute to the body of knowledge that underpins SWCNT-based optical sensors.

A Novel Fluorescence Probe Based on Azamonardine for Detecting and Imaging Cysteine in Cells and Zebrafish with High Selectivity and Sensitivity.

A novel fluorescent probe based on azamonardine (Aza) fluorophore was designed and synthesized for the highly selective detection of cysteine (Cys) in vivo and in vitro. After reacting with acryloyl chloride, the fluorescence of Aza is effectively quenched, resulting in the formation of the Aza-acryl probe. Upon the addition of Cys, the ester bond of Aza-acryl is cleaved, releasing a new compound (Compound 1) with strong fluorescence, thereby achieving fluorescence turn-on detection of Cys. The structure of Aza-acryl was characterized using X-ray crystallography and NMR spectroscopy. Additionally, density functional theory was employed to elucidate the quenching mechanism of the acyl group on the Aza. Aza-acryl exhibits high selectivity towards Cys and distinguishes it from other biothiols such as homocysteine (Hcy) and glutathione (GSH). The mechanism of Aza-acryl for detecting Cys was investigated through HPLC, NMR spectroscopy, high-resolution mass spectrometry, and reaction kinetics experiments. Aza-acryl demonstrates excellent imaging capabilities for Cys in cells and zebrafish, providing a reliable and selectable tool for the detection and imaging of Cys in biological systems.

Naphthalimide-based multiresponsive copper metal-organic framework for ratiometric detection of ClO− and turn-on sensing Fe3+, Cr3+, and Al3+ in water

Developing a single fluorescent sensor for multi-analytes with distinguishable output signals is significant but challenging. Herein a novel 2D copper metal-organic framework, namely NBCu, has been facilely prepared based on the assembling of imidazole and morpholine functionalized 1, 8-naphthalimide, 1, 3, 5-benzenetricarboxylic acid and Cu2+ ions, which presents solvent and pH stability (2.0–12.0) and thermostability. In addition, NBCu shows a significant and selective ratiometric fluorescent response to ClO− with more than 200-fold enhancement in fluorescence ratio (F473/F394), mainly due to an inhibited photoinduced electron transfer (PET) process by the hydrogen bonding interactions between morpholine and HClO that generated from ClO− in water. Meanwhile, the ClO− detection limit is determined as 82.95 nM, and the sensor can be regenerated and reused 5 times. Moreover, NBCu exhibits selective turn-on fluorescence (F394) to Fe3+, Cr3+, and Al3+ with the detection limit down to 10−8 M level and can be reused up to 5 cycles. Turn-on sensing behaviors are mainly the result of the absorbance-caused enhancement (ACE) effect and hydrogen bond destruction related to the interactions between the metal ions and the MOF. Significantly, using real water samples, NBCu can be employed as a tracer for ClO− detection.

Fluorescence switch-on detection of alkaline phosphatase activity and adenosine triphosphate using vitamin B6 cofactor conjugated Mn-doped ZnS QDs

This study introduces a fluorescent nanoprobe PLP@l-Cyst-Mn-ZnS obtained through post-functionalization of l-cysteine capped Mn-doped ZnS quantum dots (l-Cyst-Mn-ZnS QDs) with pyridoxal 5′-phosphate (PLP). The functionalization process involves the formation of a Schiff base between PLP and l-Cyst, leading to the quenching of fluorescence emission at 603 nm. The quenched PLP@l-Cyst-Mn-ZnS acts as a highly sensitive fluorescent turn-on probe for alkaline phosphatase (ALP) and adenosine triphosphate (ATP). ALP catalytically dephosphorylates the functionalized PLP into pyridoxal (PL). In contrast, the interaction of ATP with the functionalized PLP suppresses the electron transfer process leading to the recovery of fluorescence emission at 603 nm. This nanoprobe exhibits exceptionally high sensitivity enabling the estimation of ALP and ATP concentrations as low as 0.006 U/L and 0.14 µM, respectively. The practical applicability of PLP@l-Cyst-Mn-ZnS is demonstrated by accurately quantifying spiked ALP and ATP in human serum and plasma. This work highlights the potential of PLP@l-Cyst-Mn-ZnS as a versatile and efficient nanoprobe for biomedical applications.

Reversible and Turn-On Fluorescence Detection of Phosphate in Aqueous Solution and Living Cell Imaging by Supramolecular Metallacycles with AIE-Active Ligands.

Luminescent supramolecular metallacycles have attracted great interest as a new promising class of sensing substrates. In this work, two tetraphenylethene (TPE)-based diimidazole and dipyrazole ligands with the aggregation-induced emission (AIE) feature were designed for the construction of supramolecular tetragonal metallacycles 1-4 with two 90° mononuclear [(bpy)M]2+ or dinuclear [(bpy)2M2]4+ acceptors (bpy = 2,2'-dipyridine; M = Pd, Pt), in which the fluorescence can be quenched to an "off" state due to the ligand-to-metal charge transfer (LMCT). Metallacycle 1 was utilized as a fluorescence sensor for phosphate (PO43-) detection in aqueous solution by means of disassembly, leading to the release of the ligand. Additionally, the metallacycle can be regenerated through self-assembly via the introduction of Pd(II) acceptors. PO43- was detected using TPE-based metallacycles over a wide concentration range, with a detection limit as low as 2.1 × 10-8 M. Furthermore, sensor 1 also presented the semiquantitative visual detection ability for PO43- in the test paper mode via fluorescence changes. The aforementioned studies not only enhance the current research on fluorescent materials but also offer a strategy for the creation of stimuli-responsive supramolecular coordination complexes.

Molecular recognition of carbonate ion using a novel turn-on fluorescent probe

A novel turn-on fluorescent probe 3 was synthesized by condensing salicylaldehyde and nicotinic hydrazide for the selective detection of CO32– in aqueous medium. Probe 3 exhibited a turn-on fluorescence response toward CO32– with excellent selectivity, sensitivity (DL = 2.76 μM), and good reversibility. The binding constant (K) of probe 3 with CO32– was calculated to be 5 × 103 M−1 (log K 3.69). The 1:1 stoichiometry of the complex between probe 3 and CO32– ions was confirmed by Job's plot and ESI-MS spectra. Deprotonation and hydrogen-bonding interactions are involved in the recognition of CO32– ion, which was also suggested by 1H NMR, ESI-MS spectra, and Density Functional Theory (DFT) calculations. Moreover, an INHIBIT type molecular logic gate was constructed by using 3:CO32– and CH3COOH as inputs and current signal as output. Owing to the practical applications, probe 3 demonstrated its efficiency in quantifying CO32– ion in real water samples through standard addition method, thus showcasing its potential in real environment. Further, the MTT assay indicated very low cytotoxicity (IC50 = 1 mM) of probe 3 and also the cell imaging experiments demonstrated the effective sensing of CO32– ions with probe 3 in the biological systems.

Kidney-Targeted Near-Infrared Fluorescence Probe Reveals That SO2 Is a Biomarker for Cisplatin-Induced Acute Kidney Injury.

With the widespread use of drugs, drug-induced acute kidney injury (AKI) has become an increasingly serious health concern worldwide. Currently, early diagnosis of drug-induced AKI remains challenging because of the lack of effective biomarkers and noninvasive imaging tools. SO2 plays important physiological roles in living systems and is an important antioxidant for maintaining redox homeostasis. However, the relationship between SO2 (in water as SO32-/HSO3-) and drug-induced AKI remains largely unknown. Herein, we report the highly sensitive near-infrared fluorescence probe DSMN, which for the first time reveals the relationship between SO2 and drug-induced AKI. The probe responds to SO32-/HSO3- selectively and rapidly (within seconds) and shows a significant turn-on fluorescence at 710 nm with a large Stokes shift (125 nm). With these properties, the probe was successfully applied to detect SO2 in living cells and mice. Importantly, the probe can selectively target the kidneys, allowing for the detection of changes in the SO2 concentration in the kidneys. Based on this, DSMN was successfully used to detect cisplatin-induced AKI and revealed an increase in the SO2 levels. The results indicate that SO2 is a new biomarker for AKI and that DSMN is a powerful tool for studying and diagnosing drug-induced AKI.