Cy3B™: Improving the Performance of Cyanine Dyes

The spectral properties of a rigidified trimethine cyanine dye, Cy3B have been characterised. This probe has excellent fluorescent properties, good water solubility and can be bioconjugated. The emission properties of this fluorophore have also been investigated upon conjugation to an antibody. This study compared the conjugated emission properties of Cy3B with other commercially available fluorophores emitting at similar wavelengths.     

Optical and Thermal Properties of Nickel-Azo Dyes for Digital Versatile Disc-Recordable

We investigate the absorption spectra, optical constants and thermal decomposition as well as red-light (650nm) static recording properties of three novel nickel-azo dye films based on 4-methylthiazole, beuzothiazole and 6-methylbenzothiazole. Particularly, we obtain the nickel-azo complex film based on 4-methylthiazole, peaking at 562nm and 613nm, with higher refractive index (n = 2.46) and lower extinction coefficient (k = 0.18) at the wavelength 650nm and a sharp threshold of thermal decomposition at 330℃. The results of the static optical recording test of this dye film indicate that high reflectivity contrast of 51% can be observed at a laser writing power of 5.9mW and pulse width of 350ns. These results imply that the nickel-azo complex based on 4-methvlthiazole is a uromising candidate for a recordinz medium of digital versatile disc-recordable.     

Colorimetric and Ratiometric Fluorescence Detection of HSO3− With a NIR Fluorescent Dye

Journal of Fluorescence - Bisulfite (HSO3?) has been widely used in food and industry, which has brought convenience to human life, but also seriously endangered human health. In this work,...     

Novel Heptamethine Cyanine Dyes with Large Stokes’ Shift for Biological Applications in the Near Infrared

A series of novel functionalized, water-soluble, pH-unsensitive, highly photostable heptamethine cyanine dyes (HCDs) has been synthesized. The aim of the synthesis was to obtain novel effective probes for fluorescence detection in the near infrared. Synthesis and characterization of a special HCD with large Stokes’ shift (>100 nm), bioconjugation to IgG and effect of pH upon the new structure are presented.     

Phenolic Hydroxyl Group–Carbon Dots as a Fluorescent Probe for the Detection of Hydrogen Peroxide and Glucose in Milk

Journal of Applied Spectroscopy - In order to directly detect the concentration of glucose in milk, carbon dots (CDs) rich in phenolic hydroxyl groups were synthesized in one step as a fluorescent...     

Detection of an α-Muonium-substituted methyl radical

Mössbauer spectroscopic and magnetic measurements have been made on a novel magnetic protein produced by the controlled reconstitution of ferritin. The data indicate that the predominant mineral form in the iron-containing cores is maghemite (-Fe₂O₃) rather than magnetite (Fe₃O₄).     

Highly Selective and Sensitive Colorimetric and Fluorescent Chemosensors for Rapid Detection of Cyanide Anions in Aqueous Medium: Investigation on Supramolecular Recognition of Tweezer‑shaped Salophenes

Journal of Fluorescence - Three tweezer?shaped salophenes having catechols (1), phenols (2) and anisoles (3) units in conjunction to the dipodal Schiff bases have been applied for the optical...     

Time course and progression of wild type α-Synuclein accumulation in a transgenic mouse model

Background

Progressive accumulation of α-synuclein (α-Syn) protein in different brain regions is a hallmark of synucleinopathic diseases, such as Parkinson’s disease, dementia with Lewy bodies and multiple system atrophy. α-Syn transgenic mouse models have been developed to investigate the effects of α-Syn accumulation on behavioral deficits and neuropathology. However, the onset and progression of pathology in α-Syn transgenic mice have not been fully characterized. For this purpose we investigated the time course of behavioral deficits and neuropathology in PDGF-β human wild type α-Syn transgenic mice (D-Line) between 3 and 12 months of age.

Results

These mice showed progressive impairment of motor coordination of the limbs that resulted in significant differences compared to non-transgenic littermates at 9 and 12 months of age. Biochemical and immunohistological analyses revealed constantly increasing levels of human α-Syn in different brain areas. Human α-Syn was expressed particularly in somata and neurites of a subset of neocortical and limbic system neurons. Most of these neurons showed immunoreactivity for phosphorylated human α-Syn confined to nuclei and perinuclear cytoplasm. Analyses of the phenotype of α-Syn expressing cells revealed strong expression in dopaminergic olfactory bulb neurons, subsets of GABAergic interneurons and glutamatergic principal cells throughout the telencephalon. We also found human α-Syn expression in immature neurons of both the ventricular zone and the rostral migratory stream, but not in the dentate gyrus.

Conclusion

The present study demonstrates that the PDGF-β α-Syn transgenic mouse model presents with early and progressive accumulation of human α-Syn that is accompanied by motor deficits. This information is essential for the design of therapeutical studies of synucleinopathies.     

Utilization of Electromagnetic Detector for Selection and Detection of High-Frequency Relic Gravitational Waves

It is shown that the coupling system between fractal membranes and a Gaussian beam passing through a static magnetic field has strong selection capability for the stochastic relic gravitational wave （GW） background. The relic GW components propagating along the positive direction of the symmetrical axis of the Gaussian beam might generate an optimal electromagnetic perturbation, while the perturbation produced by the relic GW components propagating along the negative and perpendicular directions to the symmetrical axis will be much less than the former, and the influence of the random fluctuation of the relic GWs to such effect can be neglected. The high-frequency relic GWs satisfying the parameters requirement （h - 10^-31 or larger）, frequency resonance and “direction coupling”, in principle, would be selectable and measurable in seconds.     

Rhodamine B-Coated Gold Nanoparticles as Effective “Turn-on” Fluorescent Sensors for Detection of Zinc II Ions in Water

We designed a fluorescence resonance energy transfer system consisting of fluorophore Rhodamine B and gold nanoparticles for sensing of zinc ions in aqueous solution. The electrostatic attraction between positively charged N-atoms in Rhodamine molecules and negatively charged citrate corona of gold nanoparticles led to substantial fluorescence quenching. However, the quenching is switched off in the presence of zinc ions and therefore the system can be used as an effective “turn-on” fluorescence sensor. UV-Vis absorption, fluorescence spectroscopy, and transmission electron microscopy were used for sensor evaluation. The approach of “turn-on” fluorescence has real potential for sensing metallic ions in water.     

Structurally Rigid 2,6-distyrylpyridines—A New Class of Fluorescent Dyes. 1. Synthesis, Steric Constitution and Spectral Properties

A group of structurally rigid analogues of 2,6-distyrylpyridine was synthesised. Molecular geometry of the synthesised dyes in solutions was studied by ¹ H-NMR, electronic absorption and fluorescence spectrometry. The spectral data testify all the compounds exist in E-configuration of their styryl residues. The most planar molecular conformation is typical for the compounds with five-membered side aromatic moieties. In the case of pyridines with six-membered aromatic residues steric hindrance results in turning the above mentioned cyclic groups out of the plane of the central pyridine moiety. The violation of planarity in this case is not significant and saves the possibility of -electronic conjugation in the molecules. The synthesised compounds are characterized by high fluorescence quantum yields in solutions. The electronic absorption spectra of titled pyridines demonstrate low sensitivity to the nature of the substituents introduced into the side aromatic rings. In contrast to this, the fluorescence bands considerably change their position under the influence of electron donor substituents. The fluorescence spectra display substantial positive solvatofluorochromism only in the cases of the dialkylamino-derivatives, especially on going from aprotic solvents to proton donor ones. Generally, the synthesised structurally rigid distyrylpyridine derivatives have prospects for their application as multi-purposes fluorescent probes.     

The α-efficiency of corals and its importance for ESR-dating

The uncertainty in an ESR age results almost completely from the error in the evaluation of the annual dose. In the case of corals, α-efficiency has a high influence on D_E (Paleodose). The published k_α-values vary from 0.05 to 0.2, so the correct determination of k_α is crucial. In this experiment, based on direct irradiation with an ²⁴¹Am-source, we used seven samples (20 aliquots for each sample) with different ages. The first aim was to improve the measurement conditions to reach a reliable data base for the α-efficiency calculation and the second was the question of age dependency of k_α. With respect to the results of our experiments we propose an α-efficiency value for corals of 0.06–0.07 which leads to younger ages of about 7–10% less than with the k_α factor of 0.05 we used in previous studies.     

Solvatochromic Studies of Fluorescent Azo Dyes: Kamlet-Taft (π*, α and β) and Catalan (Spp, SA and SB) Solvent Scales Approach

A new metal ion-responsive azo-based fluorescent probes have been synthesized and characterized by NMR spectral techniques. Steady-state fluorometric study has been used to analyze the spectroscopic and photophysical characteristics of dye derivatives in various solvents. The fluorescence properties of these dyes are strongly solvent dependent, the wavelength of maximum fluorescence emission shifts to the red. The Kamlet-Taft and Catalan’s solvent scales were found to be the most suitable for describing the solvatochromic shifts of the absorption and fluorescence emission. The hydroxy substituted azo dye formed complexes with several metal ions (Co²⁺, Hg²⁺, Ni²⁺ and Cu²⁺) and fluorescence quenching with metal ions reveal that it can be used as a new fluorescence sensor to detect the Cu²⁺ ion.     

Copper Coordination by Familial Mutants of Parkinson’s Disease-Associated α-Synuclein

α-Synuclein (αS) is a small natively unfolded protein whose interactions with Cu²⁺ have been proposed to play a role in Parkinson’s disease (PD). We recently studied the Cu²⁺ coordination of recombinant human αS using electron paramagnetic resonance spectroscopy and identified two coordination modes at physiological pH, one anchored upon the amino terminus (mode 1) and the other anchored upon the side chain of His50 (mode 2). Here we report the Cu²⁺ coordination of the A30P, E46K and A53T mutants associated with inherited forms of PD. At physiological pH, the same two Cu²⁺ coordination modes were adopted by each of the familial mutants. The spectrum of Cu²⁺/αS(A53T) was very similar to the spectrum of the native Cu²⁺/αS complex; however, mode 2 coordination was marginally higher in the spectrum of Cu²⁺/αS(E46K) and considerably more favored in the Cu²⁺/αS(A30P) complex. The alteration in only the relative proportion of modes 1 and 2 suggests the familial mutations introduce structural changes of the protein backbone that indirectly affect the stability, but not the identity, of the native Cu²⁺ coordination modes.     

New Selective Fluorescent “Turn-On” Sensor for Detection of Hg2+ Based on a 1,8-Naphthalimide Schiff Base Derivative

Journal of Applied Spectroscopy - A new fluorescent “turn-on” sensor for Hg2+, N-allyl-4-(ethylenediamine-5-methylsalicylidene)-1,8-naphthalimide (HL) has been designed by combining a...     

Detection of parametric resonance of trapped ions for micromotion compensation

We have detected excess micromotion of trapped ions by modulating the trapping voltage. This radio-frequency (rf) modulation induces parametric resonance and excites secular motion of the trapped ions when they possess excess motion. This technique has been applied to laser-cooled ions in a linear rf trap and it provides optimum values for compensating the trapping field. We found that the technique has sensitivity equal to or greater than the conventional method for detecting excess micromotion. Because any laser propagation direction can be used, this method is expected to be applied to surface-electrode traps.