Selective Fluorescent Probe Research Articles

Plasma Tailoring of NH2-MIL-53 with Enhanced Fluorescence Emission for Simultaneous Detection of Multiple Heavy Metals in Water.

Indium, copper, and mercury are important raw materials in the electronics industry and often coexist in factory wastewater. Therefore, the development of a highly sensitive and selective method for the simultaneous detection of these heavy metal ions is of great significance for water quality monitoring and environmental protection. Herein, we report a NH2-MIL-53 fluorescent probe for the simultaneous detection of trace In3+, Cu2+, and Hg2+ in water. After a low-temperature NH3 plasma tailoring treatment for grafting electron-donor amine groups, the obtained NH2-MIL-53-M exhibited enhanced fluorescence emission intensity (∼6 times) coupled with selective adsorption of In3+, Cu2+, and Hg2+. This quenched the NH2-MIL-53-M fluorescence and allowed to significantly increase the selectivity and sensitivity for detection of In3+, Cu2+, and Hg2+. The fluorescence quenching constant (Ksv) values were 2.23 × 105, 1.00 × 105, and 2.74 × 104 M-1, while the limit of detection (LODs) values were 0.06, 0.14, and 0.53 μM, for In3+, Cu2+, and Hg2+, respectively. The concentrations of In3+, Cu2+, and Hg2+ in real environmental samples could be determined by addition of appropriate masking agents, and the recoveries were within the range of 94-110%. This study not only supplied a strategy for constructing a highly sensitive and selective fluorescent probe but also established a platform for simultaneous detection of multiple heavy metal ions in water.

A Highly Selective and Sensitive Carbazole-Based Fluorescent Probe for Peroxynitrite Detection and Cellular Imaging

A Highly Selective and Sensitive Carbazole-Based Fluorescent Probe for Peroxynitrite Detection and Cellular Imaging

Green‐Mediated Synthesis of Facile Nitrogen‐Doped Carbon Quantum Dots from Dioscorea alata as an Effective Metal Sensing Platform

AbstractNew nitrogen‐doped carbon quantum dots (NCQDs) made from Dioscorea alata (DA) extract as the carbon and nitrogen source using the hydrothermal method provide a straightforward approach for extremely sensitive and selective quantification of Cu (II) ions. In this method, aqueous extract of DA served as the carbon source and aqueous ammonia was used as the nitrogen dopant. To characterize NCQDs, a variety of analytical approaches have been utilized. The average size of NCQDs was analyzed using Transmission electron microscopy (TEM) and it was found to be 6.54 nm. Using X‐ray diffraction pattern and Raman spectroscopy, the graphitic nature of the green synthesized NCQDs was investigated. Strong green fluorescence was generated under 365 nm excitation of NCQDs, with an emission wavelength of around 460 nm. Fourier transform infrared analysis confirms the presence of various functional groups in the synthesized NCQDs. The NCQDs have the potential to serve as an extremely sensitive and selective fluorescent probe for Cu (II) ion detection, with a correlation coefficient (R2) of −0.9927 and a limit of detection of 4.2 nm. The NCQDs were then employed as probes to detect Cu (II) ions in river water and tap water.

Rational Molecular Design of a Fluorescent Probe for Selectively Sensing Human Cytochrome P450 2D6.

Cytochrome P450 2D6 (CYP2D6) is a key enzyme that mediates the metabolism of various drugs and endogenous substances in humans. However, its biological role in drug-drug interactions especially mechanism-based inactivation (MBI), and various diseases remains poorly understood, owing to the lack of molecular tools suitable for selectively monitoring CYP2D6 in complex biological systems. Herein, using a tailored molecular strategy, we developed a fluorescent probe BDPM for CYP2D6. BDPM exhibits excellent specificity and imaging capability for CYP2D6, making it suitable for the real-time monitoring of endogenous CYP2D6 activity in living bio-samples. Therefore, our tailored strategy proved useful for constructing the highly selective and enzyme-activated fluorescent probes. BDPM as a molecular tool to explore the critical roles of CYP2D6 in the pathogenesis of diseases, high-throughput screening of inhibitors and intensive investigation of CYP2D6-induced MBI in natural systems.

A Highly Sensitive and Selective Iron Ion Fluorescent Probe for Water‐Soluble Pillar[5]Arene

AbstractA novel d‐gluconamide‐functionalized water‐soluble pillar[5]arene (GWP5) was synthesized through a simple synthetic route. GWP5 showed a remarkable aggregation‐induced emission (AIE) with increasing concentration. This feature served as the basis for the construction of an AIE‐based sensor for fluorescence detection of Fe3+ with high sensitivity and selectivity, with a linear relationship between luminescence quenching and Fe3+ concentration observed from 0 to 20 µM, and a limit of detection of 7.84 × 10−9 M. This fluorescent probe could be applied to the detection of Fe3+ ions in real environmental water samples and in serum samples.

A highly selective fluorescent probe for hydrogen sulfide detection in food, water, and living cells

Hydrogen sulfide (H2S)–an endogenously produced vapor–is essential for various physiological and neurological functions. However, abnormal H2S levels can negatively impact both the environment and food quality. Herein, a novel fluorescent probe, 2-(2-benzothiazol-2-ylvinyl)-5-diethylaminophenyl-2,4-dinitrobenzenesulfonate (BDD), has been designed and synthesized for the detection of H2S. BDD exhibits high selectivity, rapid response to H2S within 6minutes, and a low limit of detection (LOD = 0.87μM), with stable emission at pH range between 6 and 12. Moreover, BDD effectively recovers H2S in water samples with recovery rates ranging from 98.8% to 102.1% and monitors both internal and external H2S in HeLa cells. Additionally, BDD-loaded test strips are promising as a tool for measuring the freshness of raw meat on-site. These findings establish the foundation for significant advancements in detecting H2S in various environments, food sources, and biological systems.

Synthesis, structure, cytotoxicity, photodynamic reactivities and molecular simulation studies of three [RuNO(Qn)(Pro)Cl] isomeric complexes

Three isomeric nitrosylruthenium complexes [RuCl(Qn)(Pro)(NO)] (1–3) were prepared, where Qn is 8-hydroxyquinoline and Pro is D-proline. The complexes 1–3 were characterized by 1H-NMR, 13C-NMR, ESI-MS, and their crystal structure were further determined with X-ray diffraction techniques. In complexes 1 and 3, the O atom of D-proline coordinated trans to NO, while the O atom of 8-quinolinol coordinated trans to NO in complexes 2, and the complexes 1 and 3 are the Ru-centered enantiomers. The photo induced NO release of the complexes were explored using time-resolved infrared spectroscopy (FT-IR) and electron paramagnetic resonance spectroscopy (EPR) in solution and the released NO was successfully imaged in living cells using a NO selective fluorescent probe. Furthermore, the cytotoxicity of the isomeric complexes against HeLa, HepG2 and A549 cells were evaluated. Among them, the selectivity for HeLa cells is significant (SI ≥ 5) with IC50 values in the range of 1.15–1.94 μM. Moreover, the three complexes spontaneously bind to human serum albumin (HSA) through hydrogen bonding and van der Waals forces, the binding constants Kb of 1–3 are 1.528 × 104, 2.390 × 104 and 2.694 × 104 M−1 at 298 K, respectively. Molecular docking analyses reveals that 1–3 bind within subdomain IB of the protein, which suggest that HSA could be a delivery vehicel for these complexes. This study provides insight into the potential biological and pharmaceutical applications for these isomeric nitrosylruthenium complexes.

A novel fluorescent probe for formaldehyde based on hydrazone formation for real food samples detection and bioimaging

Formaldehyde (FA) is an active carbonyl structure that is widely used in people's daily life, such as preservatives and fixatives. Furthermore, formaldehyde is highly toxic and has been listed as one of the three major indoor pollutants. Therefore, the development of highly sensitive and selective fluorescent probes is of great biological importance. In this article, probe X is designed to identify formaldehyde by a light-induced electron transfer (PET) process between the naphthalimide derivative and the hydrazine group based on hydrazone formation. Moreover, the probe has good optical response and excellent linearity over a wide range of formaldehyde concentrations, ensuring that formaldehyde concentration values in real complex food samples can be quantitatively recorded. In addition, the probe can monitor the changes of formaldehyde levels in living cells with good biocompatibility and image resolution.

A Highly Selective Fluorescent Probe for Monitoring the Thyroid Hormone Transporter Activity in Mammalian Cells.

Monocarboxylate transporter 8 (MCT8) is a trans-membrane transporter, which mediates the cellular delivery of thyroid hormones, L-thyroxine (T4) and 3,5,3'-triiodo-L-thyronine (T3). In humans, the MCT8 protein is encoded by the SLC16A2 gene and mutations in the transporter cause a genetic neurological disorder known as Allan-Herndon-Dudley Syndrome (AHDS). MCT8 deficiency leads to impaired transport of thyroid hormones in the brain. Radiolabelled T4 and T3 or LC/MS-MS methods have been used to monitor the thyroid hormone uptake through MCT8. Herein, we developed a fluorescent based assay to monitor the thyroid hormone uptake through MCT8. A dansyl-based fluorescent probe having L-thyroxine moiety is found to be highly selective towards MCT8 in living cells. The high selectivity of the probe towards MCT8 can be attributed to the halogen bond-mediated recognition by the transporter protein. The presence of a free carboxylic acid group is essential for the specificity of the probe towards MCT8. Additionally, the selectivity of the probe for MCT8 is abolished upon esterification of the carboxylic group. Similarly, MCT8 does not recognize the probe when it contains a free amine group.

Highly selective peptide-based fluorescent turn-on probe with large Stokes shift for the detection of Cd(II) and its applications in bio-imaging and smartphone-assisted recognition

Cadmium ions (Cd2+) is a ubiquitous environmental pollutant that endangers all forms of life, and it has become critical to develop simple and highly selective detection methods for monitoring Cd2+. Herein, a new fluorescent turn-on probe DPGC with dansyl fluorophore labelled tripeptide (ProGlyCys-NH2) was successfully synthesized using solid-phase peptide synthesis technology with Fmoc chemistry. Interestingly, DPGC showed high specificity and fluorescence “turn on” response towards Cd2+ in 100% aqueous solution. In addition, the limit of detection (LOD) for Cd2+ recognition by DPGC was calculated to be 12.4 nM. The pH test showed that DPGC had a wide detection range of 7–11 for Cd2+, and the response time was also less than 30 s. Notably, the DPGC-Cd2+ complex forms a 2:1 binding stoichiometry was determined using fluorescence titration, Job's plot, ESI-HRMS and DFT calculations. Additionally, the binding of DPGC with Cd2+ was found fluorescence reversible on addition of EDTA. Meanwhile, DPGC has excellent membrane permeability and low cytotoxicity, and was successfully employed for detecting Cd2+in living cells and zebrafish. More importantly, the colour change of Cd2+ solution with different concentrations under 365 nm UV light was detected by a smartphone App to achieve semi-quantitative visual analysis of Cd2+ ions.

Near-Infrared Fluorescent Turn-On Probe for Selective Detection of Hypochlorite in Aqueous Medium and Live Cell Imaging.

Hypochlorite, as an important reactive oxygen species (ROS), plays a vital role in many physiological and pathological processes, but an excess concentration of hypochlorite (ClO-) may become toxic to humans and cause disease. Hence, the selective and rapid detection of hypochlorite (ClO-) is necessary for human safety. Here, we report a novel near-infrared (NIR) fluorescence "turn-on" and highly selective benzophenoxazinium chloride-based fluorescent probe, BPH (benzophenoxazinium dihydroxy benzaldehyde), for hypochlorite detection. Due to hypochlorite-induced vicinal diol oxidation to the corresponding ortho benzoquinone derivative, the photoinduced electron transfer (PET) process, which was operating from vicinal diol to the benzophenoxazinium chloride receptor moiety, was suddenly inhibited, as a result of which strong NIR fluorescence "turn-on" emission was observed. The detection limit of BPH was found to be 2.39 × 10-10 M, or 0.23 nM. BPH was successfully applied for exogenous and endogenous hypochlorite detection in live MDA-MB 231 cells.

On-site visual sensing of antibiotics in food by new fluorescent lanthanide metal–organic frameworks

In recent years, foods that contaminated by the antibiotics is a serious threat to human health, so, the on-site visual detection of antibiotics in food is crucial. In this work, two new two-dimensional lanthanide metal–organic frameworks (2D LnMOFs) are synthesized by mild hydrothermal method and detailly characterized by single crystal structure analysis, photophysics, thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), FT-IR spectra. Results show the two LnMOFs has high thermo-stability, strong acid and alkaline resistance. Further studies reveal that TbMOF is a highly sensitive and selective fluorescent probe for the antibiotics of enrofloxacin (Enr) and ciprofloxacin (Cip), with a very short response time of 15 s. The limits of detection (LODs) for Enr and Cip are very low values of 190 and 70 nM, respectively, based on the method of 3σ/K, which is lower than the national food safety standard (GB 31650–2019). In addition, portable test paper based on TbMOF is fabricated, which realized the visible and on-site detection of Enr and Cip in the real samples of egg and milk.

Fluorescence Light‐Up Electrospun Membrane Incorporated with PbBr2 as a Highly Selective Fluorescence Probe for the Detection of Cs+

AbstractThis study introduces a novel fluorescent light‐up electrospun membrane, integrating PbBr2, which serves as an exceptionally selective probe for the detection of cesium ions (Cs+). Leveraging the superior optical properties of CsPbBr3 perovskite nanocrystals (PNCs), the researchers employ electrospinning technology to fabricate a test strip, namely PbBr2@polyacrylonitrile (PbBr2@PAN) nanofiber membranes, capable of swiftly detecting Cs+ in water merely by observing changes in the nanocrystals' luminescence with the naked eye. By the introduction of NH4+‐modified montmorillonite (NH4+‐MMT), PbBr2‐MT@PAN nanofiber membranes is obtained. The selectivity and sensitivity to Cs+ can be further improved because NH4+‐MMT endows PbBr2‐MT@PAN nanofiber membranes with the hydrophilic property and selective adsorption toward Cs+ ions. The membrane's fabrication is simple, scalable, and cost‐effective, with high cesium selectivity and sensitivity down to 44 ppb. This innovation enables efficient, on‐site cesium monitoring critical for environmental safety and nuclear waste management.

Fabrication of cellulose-based nanofibrous membranes as highly selective fluorescent probe for ClO[sbnd] detection and its applications in biological imaging and environment analysis

Hypochlorite (ClO) plays an important role in the human immune and environmental systems, so it is essential to develop an accurate and highly selective approach for rapid recognition of ClO. Herein, a naphthalimide derivative functionalized cellulose acetate (CA)-based fluorescent probe CA-NA-DNPH was prepared for specific detection of ClO. This probe displayed a “off-on” fluorescence change towards ClO, and the fluorescence color varied from colorless to brilliant green. CA-NA-DNPH presented eminent properties to ClO including fast response (3 min), high sensitivity (98 nM), wide pH range (3−12), and good selectivity. The recognition mechanism of CA-NA-DNPH to ClO was verified by high resolution mass spectrometry (HRMS) analysis. In addition, CA-NA-DNPH was utilized to monitor the ClO concentration in tap water and swimming pool water, and was also used to recognize ClO in living cells and zebrafish. Furthermore, the CA-NA-DNPH-based fluorescence nanofibrous membrane was successfully prepared by electrospinning technique, which provided a simple and convenient tool for detection of ClO.

Nuclear Chloride Ion-Selective Fluorescent Probe and Its Biological Applications.

Owing to the biological significance of Cl- in cells, several chemical fluorescent probes and biosensors have been constructed to monitor this anion in the cytosol and subcellular organelles. However, a fluorescent probe for the selective detection of nuclear Cl- has not been described thus far. In the current study, we developed the first nuclear Cl--selective biosensor, Cl-YFP-NLS, whose fluorescence was effectively quenched by this anion, and demonstrated that it is an efficient and powerful tool for determining the levels of nuclear Cl-. The results of cell studies using Cl-YFP-NLS as the probe suggested that the level of Cl- in the nucleus is lower than that in the cytosol. In addition, Cl-YFP-NLS along with lysosomal (Lyso-MQAE) and mitochondrial Cl--selective fluorescent probes (Mito-MQAE) were utilized to determine the effects of various substances on the levels of Cl- in subcellular organelles. The results showed that lysosomotropic agents decrease the lysosomal Cl- concentration and increase the levels of mitochondrial and nuclear Cl-. Also, observations suggested that substances capable of inducing mitochondrial outer membrane permeabilization without inducing lysosomal membrane permeabilization increase mitochondrial and nuclear Cl- concentrations but they do not affect the level of lysosomal Cl-. Moreover, a substance directly disrupting nuclear pore complexes increased the level of nuclear Cl- and did not change the levels of lysosomal and mitochondrial Cl-. Finally, nucleus-affecting substances that cause deoxyribonucleic acid damage and activate p53 and Bax increased the levels of mitochondrial and nuclear Cl- without influencing the level of lysosomal Cl-.

Visualization of nonsmall-cell lung cancer by near-infrared fluorescence imaging with tumor-targeting peptide ABT-510

Nonsmall-cell lung cancer (NSCLC) is the most frequent type of lung cancer, with early surgical treatment proving vital for prolonged patient survival. However, precise visualization of NSCLC remains a challenge due to limited molecular imaging probes, the unique anatomical structure of the lungs, and respiratory movement interference. In this study, we investigated the potential utility of CD36, which is highly expressed in NSCLC, as an imaging target. A selective and water-soluble fluorescent probe, MPA–ABT-510, was successfully constructed by coupling ABT-510 with MPA, a near-infrared (NIR) fluorescent dye. Molecular docking analysis shows that MPA–ABT-510 possesses strong binding affinity to the CD36 protein, with specific hydrogen bond interactions at defined amino acid residues. In vitro assays reveals that the fluorescein isothiocyanate-labeled peptide ABT-510 specifically binds to the CD36-high expressing NSCLC cell lines H1299 and A549. In vivo imaging verifies that the MPA–ABT-510 efficiently accumulates in the tumor site with a distinct fluorescent signal. Ex vivo imaging revealed that tumor-to-lung fluorescence ratios for subcutaneous and orthotopic H1299 mouse models were 7.19 ± 0.73 and 1.91 ± 0.42, respectively, while those for A549 mice were 5.53 ± 0.64 and 1.77 ± 0.41, respectively. Biodistribution analysis demonstrated efficient MPA–ABT-510 uptake in H1299 and A549 liver metastases models with tumor-to-liver fluorescence ratios of 2.47 ± 0.48 and 2.19 ± 0.22, respectively. High MPA–ABT-510 accumulation was evident in A549 intestinal metastases models, as evidenced by tumor-to-colorectal fluorescence ratios of 4.27 ± 0.11. MPA–ABT-510 exhibits superior imaging capabilities with minimal safety concerns, so it is a promising candidate for NSCLC surgical navigation.

Highly Selective Drug-Derived Fluorescent Probes for the Cannabinoid Receptor Type 1 (CB1R).

The cannabinoid receptor type 1 (CB1R) is pivotal within the endocannabinoid system regulating various signaling cascades with effects in appetite regulation, pain perception, memory formation, and thermoregulation. Still, understanding of CB1R's cellular signaling, distribution, and expression dynamics is very fragmentary. Real-time visualization of CB1R is crucial for addressing these questions. Selective drug-like CB1R ligands with a defined pharmacological profile were investigated for the construction of CB1R fluorescent probes using a reverse design-approach. A modular design concept with a diethyl glycine-based building block as the centerpiece allowed for the straightforward synthesis of novel probe candidates. Validated by computational docking studies, radioligand binding, and cAMP assay, this systematic approach allowed for the identification of novel pyrrole-based CB1R fluorescent probes. Application in fluorescence-based target-engagement studies and live cell imaging exemplify the great versatility of the tailored CB1R probes for investigating CB1R localization, trafficking, pharmacology, and its pathological implications.

Benzo-Crown-Ether Functionalized O-BODIPY Probes for Cations - A Selective Fluorescent Probe for Ba2.

Herein, we report the synthesis and sensing characteristics of 4,4'-methoxy-substituted BODIPY fluorescent probes (O-BODIPYs) 3, 4 and 5 equipped with differently sized benzo-crown ethers (cf. Scheme 1, 3 (benzo-15-crown-5), 4 (benzo-18-crown-6) and 5 (benzo-21-crown7)). O-BODIPYs 3, 4 and 5 exhibited in comparison to their known F-BODIPY analogues 3a, 4a and 5a (cf. Scheme 1) an improved solubility in aqueous medium and higher fluorescence quantum yields. Fluorometric study in aqueous solutions of 3, 4 and 5 in the presence of different cations show cation induced fluorescence enhancements (FE). Compared to the benzo-crown ether substituted F-BODIPY analogues 3a, 4a and 5a, we found for the free O-BODIPYs 3, 4 and 5 higher fluorescence quantum yields (φf) but lower cation induced FEs. We show that in aqueous medium the fluorescence quenching process (OFF switching), a photoinduced electron transfer, in O-BODIPYs 3, 4 and 5 is less effective and consequently sensitive and selective ON switching of the fluorescence by cations, too. Albeit these observations the novel benzo-21-crown-7 equipped fluorescent probe 5 exhibits a good fluorometric Ba2+ selectivity and Ba2+ sensitivity in conjunction to their aqueous solubility.

Targeting zincosomes to unveil lysosomal zinc ion dynamics and their role in exacerbating Alzheimer's pathology

Maintaining lysosomal zinc (Zn2+) homeostasis is crucial for cellular functionality, with its dysregulation implicated in the progression of neurodegenerative disorders, notably Alzheimer's disease (AD). The paucity of effective tools for precise lysosomal Zn2+ visualization has been a significant barrier to elucidating its role in AD. In response, a highly sensitive and selective novel fluorescent probe based on a salicylaldehyde Schiff base derivative, SSb, was developed to visualize Zn2+ dynamics. Our findings unveil a previously uncharacterized Zn2+ transport mechanism via zincosomes, highlighting their engulfment by mitochondria during autophagy, facilitated by SSb. Significantly, Zn2+ levels were found to be elevated in the brains of AD model mice, associated with amyloid-β (Aβ) deposits. Additionally, our study indicates an abnormal activation of autophagy in AD models, suggesting that Zn2+ increment may exacerbate AD pathology by fostering Aβ deposition and toxicity. This investigation provides valuable insights into Zn2+ homeostasis and its impact on AD, laying the groundwork for novel diagnostic and therapeutic avenues in combating AD, further reflecting the interdisciplinary nature of chemical engineering and biomedical research.

Au nanoparticles decorated graphitic carbon nitride nanosheets as a sensitive and selective fluorescence probe for Fe3+ and dichromate ions in aqueous medium

Graphitic carbon nitride mutated with metal nanoparticles has captivated great interest as an effective fluorescent sensor for the detection of harmful ions present in water. In the present work, bulk-gCN was synthesized using melamine as precursor, and further Au-gCN nanocomposite were fabricated via in-situ direct reduction deposition method. The structural, morphological, compositional, stability and optical properties of bulk gCN and Au-gCN nanocomposite were examined using various scattering and spectroscopic techniques such as HRTEM, XPS, XRD and SEM. The synthesized bulk gCN straggles during selectivity studies with different cations and anions because of its uneven surface morphology, however in Au-gCN gold nanoparticles are uniformly distributed on the gCN sheets which results in its enhanced selectivity over bulk gCN. This leads to the fabrication of an optical sensor for Fe3+ and Cr2O72− ions with limit of detection of 4.62 and 2.77 μM, respectively. The sensing of Fe3+ ions corresponds to the photoinduced electron transfer (PET) mechanism, while the detection of chromate species is associated with an inner filter effect (IFE). The practical applicability of the sensor was also evaluated for different environmental water samples. The high stability, sensitivity, and specificity of Au-gCN nanocomposite make it a potential fluorescent probe for Fe3+ and Cr2O72− ions in water samples.