Dual Fluorescent Probe Research Articles

Fluorescent “on-off-on” switching sensor based on CdTe quantum dots coupled with multiwalled carbon nanotubes@graphene oxide nanoribbons for simultaneous monitoring of dual foreign DNAs in transgenic soybean

With the increasing concern of potential health and environmental risk, it is essential to develop reliable methods for transgenic soybean detection. Herein, a simple, sensitive and selective assay was constructed based on homogeneous fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) and multiwalled carbon nanotubes@graphene oxide nanoribbons (MWCNTs@GONRs) to form the fluorescent “on-off-on” switching for simultaneous monitoring dual target DNAs of promoter cauliflower mosaic virus 35s (P35s) and terminator nopaline synthase (TNOS) from transgenic soybean. The capture DNAs were immobilized with corresponding QDs to obtain strong fluorescent signals (turning on). The strong π–π stacking interaction between single-stranded DNA (ssDNA) probes and MWCNTs@GONRs led to minimal background fluorescence due to the FRET process (turning off). The targets of P35s and TNOS were recognized by dual fluorescent probes to form double-stranded DNA (dsDNA) through the specific hybridization between target DNAs and ssDNA probes. And the dsDNA were released from the surface of MWCNTs@GONRs, which leaded the dual fluorescent probes to generate the strong fluorescent emissions (turning on). Therefore, this proposed homogeneous assay can be achieved to detect P35s and TNOS simultaneously by monitoring the relevant fluorescent emissions. Moreover, this assay can distinguish complementary and mismatched nucleic acid sequences with high sensitivity. The constructed approach has the potential to be a tool for daily detection of genetically modified organism with the merits of feasibility and reliability.

Dual Fluorescent- and Isotopic-Labelled Self-Assembling Vancomycin for in vivo Imaging of Bacterial Infections.

The increase of bacterial resistance demands rapid and accurate diagnosis of bacterial infections. Biosurface-induced supramolecular assembly for diagnosis and therapy has received little attention in detecting bacterial infections. Herein we present a dual fluorescent-nuclear probe based on self-assembly of vancomycin (Van) on Gram-positive bacteria for imaging bacterial infection. A Van- and rhodamine-modified peptide derivative (Rho-FF-Van), as the imaging agent, binds to the terminal peptide of the methicillin-resistant staphylococcus aureus (MRSA) and self-assembles to form nanoaggregates on the surface of MRSA. In an in vivo myositis model, Rho-FF-Van results in a significant increased fluorescence signal at the MRSA infected site. Radiolabeled with iodine-125, Rho-FF-Van shows strong radioactive signal in the MRSA-infected lungs in a murine model. This novel dual fluorescent and nuclear probe promises a new way for in vivo imaging of bacterial infections.

Dual Fluorescent‐ and Isotopic‐Labelled Self‐Assembling Vancomycin for in vivo Imaging of Bacterial Infections

AbstractThe increase of bacterial resistance demands rapid and accurate diagnosis of bacterial infections. Biosurface‐induced supramolecular assembly for diagnosis and therapy has received little attention in detecting bacterial infections. Herein we present a dual fluorescent‐nuclear probe based on self‐assembly of vancomycin (Van) on Gram‐positive bacteria for imaging bacterial infection. A Van‐ and rhodamine‐modified peptide derivative (Rho‐FF‐Van), as the imaging agent, binds to the terminal peptide of the methicillin‐resistant staphylococcus aureus (MRSA) and self‐assembles to form nanoaggregates on the surface of MRSA. In an in vivo myositis model, Rho‐FF‐Van results in a significant increased fluorescence signal at the MRSA infected site. Radiolabeled with iodine‐125, Rho‐FF‐Van shows strong radioactive signal in the MRSA‐infected lungs in a murine model. This novel dual fluorescent and nuclear probe promises a new way for in vivo imaging of bacterial infections.

A Dual Functional Electroactive and Fluorescent Probe for Coupled Measurements of Vesicular Exocytosis with High Spatial and Temporal Resolution

AbstractIn this work, Fluorescent False Neurotransmitter 102 (FFN102), a synthesized analogue of biogenic neurotransmitters, was demonstrated to show both pH‐dependent fluorescence and electroactivity. To study secretory behaviors at the single‐vesicle level, FFN102 was employed as a new fluorescent/electroactive dual probe in a coupled technique (amperometry and total internal reflection fluorescence microscopy (TIRFM)). We used N13 cells, a stable clone of BON cells, to specifically accumulate FFN102 into their secretory vesicles, and then optical and electrochemical measurements of vesicular exocytosis were experimentally achieved by using indium tin oxide (ITO) transparent electrodes. Upon stimulation, FFN102 started to diffuse out from the acidic intravesicular microenvironment to the neutral extracellular space, leading to fluorescent emissions and to the electrochemical oxidation signals that were simultaneously collected from the ITO electrode surface. The correlation of fluorescence and amperometric signals resulting from the FFN102 probe allows real‐time monitoring of single exocytotic events with both high spatial and temporal resolution. This work opens new possibilities in the investigation of exocytotic mechanisms.

A Dual Functional Electroactive and Fluorescent Probe for Coupled Measurements of Vesicular Exocytosis with High Spatial and Temporal Resolution.

In this work, Fluorescent False Neurotransmitter 102 (FFN102), a synthesized analogue of biogenic neurotransmitters, was demonstrated to show both pH-dependent fluorescence and electroactivity. To study secretory behaviors at the single-vesicle level, FFN102 was employed as a new fluorescent/electroactive dual probe in a coupled technique (amperometry and total internal reflection fluorescence microscopy (TIRFM)). We used N13 cells, a stable clone of BON cells, to specifically accumulate FFN102 into their secretory vesicles, and then optical and electrochemical measurements of vesicular exocytosis were experimentally achieved by using indium tin oxide (ITO) transparent electrodes. Upon stimulation, FFN102 started to diffuse out from the acidic intravesicular microenvironment to the neutral extracellular space, leading to fluorescent emissions and to the electrochemical oxidation signals that were simultaneously collected from the ITO electrode surface. The correlation of fluorescence and amperometric signals resulting from the FFN102 probe allows real-time monitoring of single exocytotic events with both high spatial and temporal resolution. This work opens new possibilities in the investigation of exocytotic mechanisms.

Fluorescein-Based Chromogenic and Ratiometric Fluorescence Probe for Highly Selective Detection of Cysteine and Its Application in Bioimaging.

A dual mode fluorescent probe, which is based on an integration of fluorescein and coumarin fluorophores, was developed for the discrimination of Cys from Hcy and GSH. This probe (2) shows the advantage of quick reaction (5 min) with Cys, resulting in a strong fluorescence turn-on response when excited at 450 nm. Notably, it also demonstrates the ratiometric fluorescence property while excited by a shorter wavelength (332 nm). All of results suggest probe 2 has a high selectivity toward Cys even in the presence of other amino acids, cations and anions. The detection limit of Cys was calculated as 0.084 μM, which was much lower than the intracellular concentration. 1H NMR, MS and DFT calculation were used to reveal the detection mechanism further. Finally, this low cytotoxic probe was successfully applied in bioimaging within HepG2 cells.

A coumarin-based colorimetric and fluorescent dual probe for palladium(ii) ions that can be used in live cells

The new sensor containing oxime-ether can detect Pd2+with high sensitivity and high selectivity in aqueous medium.

CV-APC, a colorimetric and red-emitting fluorescent dual probe for the highly sensitive detection of palladium

A highly sensitive colorimetric and red-emitting fluorescent dual probe was synthesized and applied to imaging palladium species based on the Tsuji–Trost reaction.

A dual analyte fluorescent chemosensor based on a furan-pyrene conjugate for Al3 + & HSO3−

A simple chalcone based dual analyte fluorescent probe FPC for Al3+ and HSO3− ions was developed. FPC detects both the analytes through a “turn off-on” approach and by the PET and ICT mechanism. FPC showed high selectivity and sensitivity for Al3+ and HSO3− ions detection over other interfering and competing metal ions. In addition, the LOD of FPC for sensing Al3+ and HSO3− ions was found to be 1.60×10−7M and 0.17×10−6M respectively. An electrochemical desalination technique was employed for the complete removal of Al3+ ions from the environmental water samples by using the probe FPC.

Development of an engineered carbazole/thiazole orange conjugating probe for G-quadruplexes

The development of selective and sensitive probes for sensing G-quadruplexes either in vitro or in cellulo has been the focus of investigation for a long time. Of those investigated, 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC) is a promising fluorescent probe utilized in many studies investigating G-quadruplex structures. However, its shortcomings, including similar fluorescence responses for G-quadruplex and duplex DNA and green but not red fluorescent emission, might restrict the further application of BMVC. In this study, in order to improve the selectivity and optical properties of BMVC, we engineered a new probe (TO-CZ) by incorporating thiazole orange (TO) into the structure of BMVC. We next found that TO-CZ can act as a colorimetric and red-emitting fluorescent dual probe selective for G-quadruplexes without affecting the G-quadruplex topology. Further experiments showed that a 2:1 binding model involving the external binding of TO-CZ to both ends of the G-quadruplex is the most possible binding mode. Furthermore, we applied TO-CZ in sensing G-quadruplexes both in vitro and in cellulo, and found that TO-CZ can selectively and sensitively visualize G-quadruplexes. Notably, TO-CZ might be used to map DNA and RNA G-quadruplexes in cellulo, showing its great potential in investigating intracellular G-quadruplex structures.

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes

Phosphoinositides in the cell membrane are signaling lipids with multiple cellular functions. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a determinant phosphoinositide of the plasma membrane (PM), and it is required to modulate ion channels, actin dynamics, exocytosis, endocytosis, intracellular signaling, and many other cellular processes. However, the spatial organization of PI(4,5)P2 in the PM is controversial, and its nanoscale distribution is poorly understood due to the technical limitations of research approaches. Here by utilizing single molecule localization microscopy and the Pleckstrin Homology (PH) domain based dual color fluorescent probes, we describe a novel method to visualize the nanoscale distribution of PI(4,5)P2 in the PM in fixed membrane sheets as well as live cells.

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes.

Phosphoinositides in the cell membrane are signaling lipids with multiple cellular functions. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a determinant phosphoinositide of the plasma membrane (PM), and it is required to modulate ion channels, actin dynamics, exocytosis, endocytosis, intracellular signaling, and many other cellular processes. However, the spatial organization of PI(4,5)P2 in the PM is controversial, and its nanoscale distribution is poorly understood due to the technical limitations of research approaches. Here by utilizing single molecule localization microscopy and the Pleckstrin Homology (PH) domain based dual color fluorescent probes, we describe a novel method to visualize the nanoscale distribution of PI(4,5)P2 in the PM in fixed membrane sheets as well as live cells.

A red-emitting fluorescent probe for biothiols detection with a large Stokes shift

A highly selective red-emitting fluorescent probe for biothiols detection was developed. The addition of biothiols to the solution of this probe, 1, resulted in a strong red fluorescence with an obvious color change from red to claybank. This colorimetric and fluorescent dual probe exhibited a low detection limit (15 nM) and a large Stokes shift (147 nm) in detecting biothiols. Importantly, the utility of this probe for sensing intracellular thiols was successfully demonstrated in living HNE-2 cells.

A colorimetric and fluorescent turn-on probe for carbon monoxide and imaging in living cells

A colorimetric and fluorescent dual probe for CO is designed and synthesized. The probe is capable of sensitive and specific detection of CO with naked-eye through colorimetric assay in phosphate buffer from colorless to yellow, which also features 75-fold turn-on fluorescence enhancement upon exciting at 480nm with the detection limit of 26.3nM. The probe shows great potential for sensing intracellular CO without the interference in living cell imaging. On the other hand, the probe could also be utilized as an efficient and convenient visual indicator for CO gas in air by naked eyes.

A highly selective and sensitive 3-hydroxyflavone-based colorimetric and fluorescent probe for hydrogen sulfide with a large Stokes shift

A 3-hydroxyflavone-based colorimetric and fluorescence probe for hydrogen sulfide (H2S) has been developed with high sensitivity and excellent selectivity. This probe was designed based on the mechanism that H2S selectively cleaved the NBD (7-nitro-2,1,3-benzoxadiazole) ether moiety in this probe and therefore release the fluorophore, 3-hydroxyflavone. The addition of H2S to the solution of probe 1 resulted in a green fluorescence and an obvious color change from colorless to pink, indicating that this probe can serve as a colorimetric and fluorescent dual probe for H2S. Furthermore, this probe displays a rapid response and reaches to a plateau within 5 min. It also exhibits a 146 nm Stokes shift and a low detection limit (20 nM, based on S/N=3) in detecting H2S. Importantly, practical utility of this probe for the selective detection of H2S in living cells has been successfully demonstrated.

A colorimetric and fluorescent dual probe for palladium in aqueous medium and live cell imaging.

A colorimetric and fluorescent dual probe for palladium species was rationally developed by combining the resorufin fluorophore with allyl chloroformate. The probe enables the visual detection of palladium based on its vivid color change from pale yellow to pink and its fluorescence off-on response to palladium in PBS solution. The detection limit was calculated to be as low as 2.1 nM. The live cell imaging results showed that this probe could be used as an effective fluorescent probe for detecting intracellular palladium species. All these results featured its promising application prospects in the palladium analytical field.

Development of a colorimetric and NIR fluorescent dual probe for carbon monoxide

Herein, the first example of colorimetric and near-infrared fluorescent dual probe for carbon monoxide (CO) has been developed by assembling allyl chloroformate moiety with naphthofluorescein fluorophore, which enables the label-free and visual detection of CO.

A new quinoline-based fluorescent probe for Cd(2+) and Hg(2+) with an opposite response in a 100% aqueous environment and live cell imaging.

A new quinoline-based fluorescent probe was synthesized and characterized. Probe showed opposite fluorescence responses toward Cd(2+) (turn-on) and Hg(2+) (turn-off) in a 100% aqueous environment. X-ray crystallography analysis and TD-DFT calculations showed the different mechanisms of CHEF-based for -Cd(2+) and PET-based for -Hg(2+) caused by different binding modes and different electronic transfer patterns. The detection limits for the analysis of Cd(2+) and Hg(2+) ions were found to be 3.9 × 10(-8) M and 9.8 × 10(-7) M, respectively. Its in vivo sensitivities to Cd(2+) and Hg(2+) were demonstrated in the EC9706 cell line with the use of a laser scanning fluorescence microscope.

A quantum dot-based dual fluorescent probe for recognition of mercuric ions and N-acetylcysteine: “On–Off–On” approach

A cadmium sulfide quantum dot based dual fluorescent "On-Off-On" probe was designed and applied for monitoring of mercuric ions and N-acetylcysteine in aqueous solution.

Frontispiece: New Dual Fluorescent Probe for Simultaneous Biothiol and Phosphate Bioimaging

Frontispiece: New Dual Fluorescent Probe for Simultaneous Biothiol and Phosphate Bioimaging