Dual Fluorescent Probe Research Articles

Tripeptide and phenylboronic acid-functionalized eco-friendly carbon dots for dual sensing of dopamine and their bioimaging applications in SH-SY5Y cells

Facile and convenient carbon dots (CDs) with excellent biocompatibility and strong fluorescence using eco-friendly sources are in high demand for sensing and bioimaging applications. In this study, we used a hydrothermal approach to synthesize highly biocompatible CDs (BCDs) from green fruit vegetables (bottle gourd). By employing the carbodiimide coupling method, these BCDs were functionalized with the tripeptide and phenylboronic acid ligands, glutathione and 4-mercaptophenylboronic acid, respectively. This method enhanced the sensing potential of the nanomaterial for the crucial neurotransmitter, dopamine (DA). These functionalized BCDs (FBCDs) exhibited significant excitation-dependent emission behavior. The BCDs and FBCDs displayed strong blue fluorescence, (λem = 460 nm) and (λem = 458 nm), under excitation wavelengths of 360 and 351 nm, respectively. The FBCDs exhibited an excellent fluorescence quenching response to DA in the wide range of concentrations between 0 and 25 μM and achieved a detection limit of 2.14 μM. The FBCDs were verified as a dual fluorescent probe by demonstrating in vitro detection of DA in SH-SY5Y (human neuroblastoma) cells. The FBCDs also enabled superior bioimaging in SH-SY5Y cells via multi-color emissions, including of blue, green, and red. The practicality of the proposed FBCDs was also investigated in human serum.

Bifunctional Nitrogen and Fluorine Co-doped Carbon Dots as Fluorescence Probe for Silicon and Mercury by pH Switching.

New nitrogen and fluorine co-doped carbon dots were synthesized and used as a dual function fluorescent probe for silicon and mercury ions. The size of CDs was 10 nm. At optimum conditions (pH = 13, λex = 360 nm, and λem = 518 nm), the detection limit (DL) of silicon was 16.6 nM. Linear calibration was observed in the range of 0.8-35 µM. This fluorescence probe for silicon detection is presented for the first time and had the lowest detection limit in comparison with different previously reported techniques. In addition to the above property, these co-doped carbon dots had the second function as a fluorescence probe for mercury detection at pH = 8. The DL for mercury was 38 nM. The performance of this probe was also compared with other co-doped carbon dots. Excellent sensitivity and selectivity, simple method, low-cost materials, and applicability in real sample analysis are advantages of this dual function fluorescence probe.

A POSS-assisted fluorescent probe for the rapid detection of HClO in mitochondria with a large emission wavelength in dual channels.

Hypochlorous acid (HClO) is closely related to many diseases and is an inevitable part of the physiological processes. It is significant to detect HClO in mitochondria for getting meaningful physiological and pathological information. However, adequate tools to detect HClO with emissions in two channels are rarely reported. To achieve this target, in this work, a "turn-off" visual and near infrared (NIR) fluorescent dual emission probe D6 based on polyhedral oligomeric silsesquioxanes (POSS) was successfully designed and synthesized. D6 showed high selectivity and sensitivity to HClO. Notably, the emission wavelength of D6 reached 820 nm due to the assistance of the POSS cage. In addition, bioimaging experiments clearly showed that probe D6 promoted the visualization of exogenous and endogenous HClO in living HepG2 cells and zebrafish models.

Live-cell imaging of the nucleolus and mapping mitochondrial viscosity with a dual function fluorescent probe.

Visualization of sub-cellular organelles allows the determination of various cellular processes and the underlying mechanisms. Herein, we report a fluorescent probe, bearing push-pull substituents emitting at 600 nm and its application in cellular imaging. The probe shows dual imaging of mitochondria and nucleoli and maps mitochondrial viscosity in live cells under various physiological variations and show minimum cytotoxicity. Nucleolar staining is confirmed by RNAase digestion.

Dendrimer-Based Nanomedicine (Paramagnetic Nanoparticle, Nanocombretastatin, Nanocurcumin) for Glioblastoma Multiforme Imaging and Therapy.

In brain tumors, delivering nanoparticles across the blood-brain tumor barrier presents a major challenge. Dual mode magnetic resonance imaging and fluorescent imaging probes have been developed where relaxation based Gd-DOTA or ParaCEST agents and a Near-Infrared (NIR) fluorescent dye, DL680 were conjugated on the surface of dendrimer. The in vivo and ex vivo imaging of the dual-modality contrast agent showed excellent potential utility for identifying the location of glioma tumors. Systemic delivery of the subsequent nano-sized agent demonstrated glioma-specific accumulation, probably due to the enhanced permeability and retention effect. The biodistribution studies revealed the G5 agents have accumulated in the glioma tumor and the liver while a G3 agent only accumulated in the brain tumor but not in the liver or kidney. Hydrophobic drug molecules like Combrestatin A4 (CA4) or curcumin have also been conjugated with dendrimers that provided high aqueous solubility with improved therapeutic effect.

Porous silsesquioxane cage and porphyrin nanocomposites: sensing and adsorption for heavy metals and anions

A porous silsesquioxane cage/porphyrin nanocomposite was designed as a dual fluorescent probe for the sensing and adsorption of both heavy metal ions and anions.

Metabolic iron detection through divalent metal transporter 1 and ferroportin mediated cocktail fluorogenic probes.

A cocktail [1 + 2] dual-fluorescent probe system was developed to realize the real-time visualization of dynamic iron state changes between Fe2+ and Fe3+ at the cellular level and in multicellular organisms, providing insights into the effect of DMT1 and ferroportin on iron regulation.

Highly selective and sensitive dual-fluorescent probe for cationic Pb2+ and anionic Cr2O72−, CrO42− contaminants via a powerful indium−organic framework

Lead and chromium, indispensable raw materials, are extensively used in industrial/agricultural production. However, the subsequent Pb(II) and Cr(VI) cause severe issues in biological and environmental safety. Effective detection of Pb(II) and Cr(VI) ions in water is highly desirable, but the existing approaches exhibit high cost and time consuming et al. It is thus extremely urgent to quest for an alternative solution for addressing this issue. Ionic luminescent metal-organic frameworks (iLMOFs) have been regarded as promising optical sensors due to their inherent features of quick response, good selectivity, high sensitivity and cost effective. Regretably, most iLMOFs just response to oppositely charged analytes, perform defective detection limit and recyclability, which dramatically impede their applications. Inspired by our previously reported an anionic indium-based MOF, which could photodegrade organic dyes through both anionic and cationic dyes as photosensitizers located interior and exterior MOF framework, respectively, herein the In-MOF of 1 was successfully deployed as optical sensor to probe Pb(II) and Cr(VI). Remarkably, the highly fluorescent material performs excellently selective and sensitive quenching response towards Pb2+, Cr2O72− and CrO42− in aqueous solution associated with the detection limits of 31.4, 1.2 and 0.52 ​ppb, respectively, all of which are the smallest values among all reported MOFs. The possible fluorescence emission and quenching mechanisms of 1 were tentatively proposed. Moreover, the inspiring quantitative detection ability of 1 towards Cr(VI) have also been ensured by flawlessly maintained in 7 successive detection cycles, providing the prerequisite in practical applications.

A novel dual functional pyrene-based turn-on fluorescent probe for hypochlorite and copper (II) ion detection and bioimaging applications.

A novel dual-function fluorescent probe PPH was conveniently synthesized by linking pyrazinehydrazide unit and pyrenyl fluorophore. The present probe PPH could be used for simultaneous detection of ClO- and Cu2+ through a fluorescence turn-on response. The probe PPH displayed excellent selectivity and sensitivity towards ClO- and Cu2+ over other anions and metal ions. The detection limits of PPH for ClO- and Cu2+ were calculated to be as low as 4.02nM and 157nM, respectively. The probe PPH had good pH stability and was highly responsive to ClO- and Cu2+ in a wide pH range. Furthermore, this probe could be readily applied to visualize ClO- and Cu2+ on the test paper. Additionally, this probe was successfully utilized to the fluorescence imaging of ClO- and Cu2+ in HeLa cells.

Polyhydroquinoline nanoaggregates: A dual fluorescent probe for detection of 2,4,6-trinitrophenol and chromium (VI).

Fluorescent polyhydroquinoline (PHQ) derivative was fabricated utilizing one-pot engineered course. The PHQ derivative indicated aggregation induced emission enhancement (AIEE) with arrangement of nanoaggregates of size 11-13nm in 95% watery DMF medium. The fluorescence emission of PHQ nanoaggregates was extinguished by including TNP and Cr (VI). They indicated prevalent fluorescence quenching towards both TNP and Cr (VI) over other meddling nitro-compounds and metal particles. In light of results got we presumed that both photo-induced fluorescence quenching of PHQ nanoaggregates by TNP, while Inner Filter Effect (IFE) was in charge of fluorescence quenching of PHQ nanoaggregates by Cr (VI). The PHQ nanoaggregates empowered identification of TNP and Cr (VI) down to 0.66μM (TNP) and 0.28μM (Cr (VI)). The use of PHQ nanoaggregates were reached out for location of TNP and Cr (VI) in genuine water tests.

Development of dual function polyamine-functionalized carbon dots derived from one step green synthesis for quantitation of Cu2+ and S2- ions in complicated matrices with high selectivity.

The study of biologically important Cu2+ and S2- ions has drawn great attention in the recent years since an abnormal level of these ions is an indication for health impairment. Therefore, a reliable strategy for effective fluorescence determination of Cu2+ and S2- ions was developed. Simply, the method based on economical plant-dependent thermolysis procedure for efficient green synthesis of water dispersible luminescent polyamine-based carbon dots (PA@C-dots) utilizes Vitis vinifera juice as precursor with a high quantum yield (32.1%) and good photo-stability. The fluorescent PA@C-dots were characterized by different spectroscopical, physical, and structural techniques. Furthermore, the synthesized PA@C-dots can be used as an efficient dual functional fluorescent probe for the sensitive and selective estimation of Cu2+ and S2- ions. The incorporation of Cu2+ ions and their adsorption on the surface of PA@C-dot skeleton leads to the respectable fluorescence quenching of C-dots (turn-off mode). The Cu2+-PA@C-dot was found to be sensitive to S2- ions. The addition of S2- recovers the fluorescence (turn-on mode) of Cu2+-PA@C-dots, thanks to its capacity for withdrawing Cu2+ from the shell of PA@C-dots. Fluorescence quenching in the range of 0.07-60μM Cu2+ was obtained with LOD and LOQ of 0.02 and 0.066μM, respectively. Sulfide detection provides linearity in the range of 0.8 to 95μM with LOD and LOQ of 0.24 and 0.79μM, respectively. The optimal excitation and emission wavelengths for all experiments are 435nm and 498nm, respectively. Experiment results elucidate that the proposed method is suitable for Cu2+and S2- ion detection in environmental water samples. Graphical abstract Green synthesis of polyamine-functionalized nanoprobe by thermolysis method from plant source as bifunctional sensing platform for determination of Cu2+ and S2- in environmental water samples.

Expression pattern of Nav2 in the murine CNS with development

Neuron navigator 2 (NAV2, RAINB1, POMFIL2, HELAD1, unc53H2) is essential for nervous system development. In the present study the spatial distribution of Nav2 transcript in mouse CNS during embryonic, postnatal and adult life is examined. Because multiple NAV2 proteins are predicted based on alternate promoter usage and RNA splicing, in situ hybridization was performed using probes designed to the 5′ and 3′ ends of the Nav2 transcript, and PCR products using primer sets spanning the length of the mRNA were also examined by real time PCR (qPCR). These studies support full-length Nav2 transcript as the predominant form in the wild-type mouse CNS. The developing cortex, hippocampus, thalamus, olfactory bulb, and granule cells (GC) within the cerebellum show the highest expression, with a similar staining pattern using either the 5′Nav2 or 3′Nav2 probe. Nav2 is expressed in GC precursors migrating over the cerebellar primordium as well as in the postmitotic premigratory cells of the external granule cell layer (EGL). It is expressed in the cornu ammonis (CA) and dentate gyrus (DG) throughout hippocampal development. In situ hybridization was combined with immunohistochemistry for Ki67, CTIP2 and Nissl staining to follow Nav2 transcript location during cortical development, where it is observed in neuroepithelial cells exiting the germinal compartments, as well as later in the cortical plate (CP) and developing cortical layers. The highest levels of Nav2 in all brain regions studied are observed in late gestation and early postnatal life which coincides with times when neurons are migrating and differentiating. A hypomorphic mouse that lacks the full-length transcript but expresses shorter transcript shows little staining in the CNS with either probe set except at the base of the cerebellum, where a shorter Nav2 transcript is detected. Using dual fluorescent probe in situ hybridization studies, these cells are identified as oligodendrocytes and are detected using both Olig1 and the 3′Nav2 probe. The identification of full-length Nav2 as the primary transcript in numerous brain regions suggests NAV2 could play a role in CNS development beyond that of its well-established role in the cerebellum.

Two novel colorimetric fluorescent probes: Hg2+ and Al3+ in the visual colorimetric recognition environment.

Two new dual channel Schiff base fluorescent probes, Tri-R6G and Tri-Flu, were synthesized, and can detect Hg2+ and Al3+, respectively. The two probes were characterized by FTIR, 1H NMR, 13C NMR and HRMS, and their optical properties were detected by UV and FL. Test results showed the probes' detection of Hg2+ and Al3+ compared to other metal ions (Ag+, Co2+, Cd2+, Mg2+, Cu2+, Ni2+, Ba2+, Pb2+, Cr3+, Al3+, Zn2+, Hg2+, K+, Ga2+ and Fe3+), respectively. Besides, the detection limits were determined to be 1.61 × 10−8 M and 1.15 × 10−8 M through the standard curve plot, respectively. The photoelectron transfer (PET) mechanism was guessed by the Job's plot and the infrared titration. Corresponding orbital electron distribution and molecular geometry configurations of the compounds were predicted by density functional theory (DFT). In addition, the prepared test paper changed from white to pink when the target ion was detected. The color changed from colorless to pink in a solution having a concentration of 10−5 M.

Nitrogenous carbon dot decorated natural microcline: an ameliorative dual fluorometric probe for Fe3+ and Cr6+ detection

In the modern era, the escalation of heavy metal discharges, especially from the industrial sector, is causing an enormous threat to nature. This article explores the dual sensing of heavy metals (Cr6+ and Fe3+) using a naturally formed microcline based sensor. A nano-sized microcline (M) was obtained via a facile top-down synthesis. In order to enhance the fluorescence property of the material, nitrogenous carbon-dots were loaded into the porous structure of the microcline (MCD) causing a bright blue fluorescence with remarkable stability. Detailed analysis of the composition and structure of the natural nano-sensor was carried out using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and BET analysis. This sensor material is highly selective towards Cr6+ and Fe3+, demonstrating a "turn-off" response in aqueous Fe3+ and a radical red shift of the fluorescence maxima for aqueous Cr6+. Density functional studies suggest that photoinduced electron transfer (PET) based quenching of fluorescence is responsible for these types of fluorescence alteration mechanisms. Efficient sensing of both Cr6+ and Fe3+ in various real-life water samples along with a real wastewater sample is also reported herein. A few studies have previously reported on efficient, natural material-based sensors, but they lack real-life applications due to their complicated synthesis and restricted functionalities. This work manages to overcome those drawbacks in its own fashion, providing a tremendously selective and sensitive (4 μM for Cr6+ and 19 μM for Fe3+) dual fluorescent probe.

A visible and near-infrared dual-fluorescent probe for discrimination between Cys/Hcy and GSH and its application in bioimaging.

Biothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play important roles in various physiological and pathological processes, and due to their similar structures and reaction activities, it is still challenging to simultaneously discriminate between GSH and Cys/Hcy in vivo. Hence, a novel fluorescent probe for simultaneously discriminating GSH and Cys/Hcy in biological samples is highly desirable. Herein, we presented two enhanced fluorescent probes (Cy1 and Cy2) with doubly-activated dual emission for sensitive and discriminative detection of Cys/Hcy and GSH. The probes were constructed with IR-780 and NBD linked via an ether bond, which responds to GSH with near infrared (NIR) emission at 810 nm (λex = 720 nm) and Cys/Hcy with visible green emission at 550 nm (λex = 470 nm). The probe Cy2 is operable in human serum samples, thus holding promise for its diagnosis-related application. Notably, the results of fluorescence microscopy imaging indicated that Cy2 is suitable for visualization of exogenous and endogenous biothiols in living cells. Furthermore, desirable results were obtained when the probe Cy2 was applied for bioimaging in tumor-bearing mice and acute liver injury (ALI) mice models, which revealed encouraging clinical values of this probe.

A vinyl functionalized mixed linker CAU-10 metal-organic framework acting as a fluorescent sensor for the selective detection of H2S and palladium(II)

Abstract An aluminium based metal-organic framework (MOF) (CAU-10-V-H, 1, CAU stands for Christian-Albrechts-University) was designed and synthesized by employing 5-vinyl isophthalic acid (H2IPA-V) and 1,3-benzenedicaroxylic acid (H2IPA) in 1:1 molar ratio. The compound was thoroughly characterized by a number of analytical tools. The desolvated form of the material (1′) showed great sensing performance towards Pd2+ and H2S. Instant quenching of HEPES buffer suspension of 1′ was observed in presence of H2S due to formation of ground state complex by the strong interaction between H2S and vinyl functionality. In addition, 1′ could selectively detect Pd2+ in aqueous medium with excellent sensitivity (LOD = 110 nM). The “turn-off” behavior of the material might be attributed to the interaction between Pd2+ and vinyl functional group. In addition, the XRPD pattern remains unchanged after the sensing of both H2S and Pd2+. Hence, the present material is an effective dual fluorescent probe for the detection of H2S and Pd2+.

Renally Excretable and Size-Tunable Silver Sulfide Nanoparticles for Dual-Energy Mammography or Computed Tomography.

Significant effort has been focused on developing renally-clearable nanoparticle agents since efficient renal clearance is important for eventual clinical translation. Silver sulfide nanoparticles (Ag2S-NP) have recently been identified as contrast agents for dual energy mammography, computed tomography (CT) and fluorescence imaging and probes for drug delivery and photothermal therapy with good biocompatibility. However, most Ag2S-NP reported to date are not renally excretable and are observed in vivo to accumulate and remain in the reticuloendothelial system (RES) organs, i.e. liver and spleen, for a long time, which could negatively impact their likelihood for translation. Herein, we present renally-clearable, 3.1 nm Ag2S-NP with 85% of the injected dose (ID) being excreted within 24 hours of intravenous injection, which is amongst the best clearance of similarly sized nanoparticles reported thus far (mostly between 20-75% of ID). The urinary excretion and low RES accumulation of these nanoparticles in mice were indicated by in vivo CT imaging and biodistribution analysis. In summary, these ultrasmall Ag2S-NP can be effectively eliminated via urine and have high translational potential for various biomedical applications.

A dual fluorescence probe for Zn2+ and Al3+ through differentially response and bioimaging in living cells.

A novel Schiff base fluorescent probe 7-Hydroxy-8-(((2-(hydroxymethyl)quinolin-8-yl)imino)methyl)-coumarin (XL) consist of formylcoumarin and aminoquinoline moieties was synthesized for dual detection of Zn2+ and Al3+ ions. Probe XL exhibited high selective and sensitive response towards Zn2+ and Al3+ ions through different color changes and significant fluorescence turn-on response (270 fold higher for Zn2+ and 230 fold higher for Al3+) in MeOH-H2O (4/1, v/v) over other cations, with detection limits (LOD) as low as 3.75 × 10-8 and 1.14 × 10-8 M, respectively. Moreover, probe XL exhibited preferential selectivity for Al3+ through displacing Zn2+ from the XL-Zn2+ complex by ligand-to-ligand transfer process. The binding mechanism of intramolecular charge transfer (ICT) were proposed from fluorescence and UV-vis titrations, Job's plot, 1H NMR titration, HRMS and DFT calculations. The probe was proven to be suitable for actual samples detection of Zn2+ and Al3+ ions. The complex XL-Zn2+ and XL-Al3+ exhibited dramatic fluorescent "turn-off" properties for PPi and PPi/F- respectively through snatching metal ions and released free XL. Moreover, probe XL showed low biotoxicity and sequentially "off-on-off" fluorescent bio-imaging of Zn2+/Al3+ and PPi/F- in PC12 cells.

Dual sites fluorescence probe for H2S and Hg2+ with “AIE transformers” function

Dual sites fluorescence compound 1 based on 5-bromosalicylaldehyde and 2-benzothiazoleacetonitrile was synthesized. 1 exhibited different aggregation-induced emission (AIE) state in different solution boosting different emission. Different aggregated states gave different chance for H2S and Hg2+ to respond with the formation of new aggregated states. Especially, 1 responded to H2S selectively with an ultrafast rate within 20 s. Intramolecular and intermolecular hydrogen bonding play an important role on the aggregated state conversion. Herein, the notion of “AIE Transformers” was put forward for the first time. It permits us to study their aggregation state with their photophysical and functional changes.

Water-soluble fluorescent probe for multiple ions detection based on different pH moderation

Cyanide and bisulfite are hypertoxic even in low concentration. The development of convenient methods of the detection of analyte is critically important. In this paper, the dual ions fluorescent probe CIM with superior water-solubility has been designed and synthesized with low detection limits of 0.35 μM (for CN − with a linear relationship of 0.996) and 23 nM (for HSO 3 − with a linear relationship of 0.993). Modest pH moderation could be easily used to detect the CN − and HSO 3 − without reciprocal interference. The specific detection is not interfered with other potential coexisted species. The possible recognition mechanism between probe and analytes is illustrated by NMR, HRMS and computational simulation. Both analytes undergo 1, 4-addition reaction on the ethenyl of the probe, which is rare in lots of previous work and results in a fluorescent color change. • The dual fluorescent probe CIM has superior water-solubility. • The detection limits of cyanide and bisulfite are separately 3.5 × 10 −7 M and 2.3 × 10 −8 M. • pH moderation could be used to detect CN − and HSO 3 − without reciprocal interference. • The reaction mechanism is investigated by 1H NMR spectra, HRMS and theoretical calculation. • 1,4-addition on the probe is supported by the simulated absorption spectra and emission spectra.