carbocyanines and 3-3--diethylthiatricarbocyanine

There is a growing interest to use non-invasive optical imaging methods to study central nervous system diseases. The application of a myelin-binding fluorescent dye, 3,3-diethylthiatricarbocyanine iodide (DBT) was recently described for in vivo optical imaging of demyelination in the mouse. In the present study we aimed at adapting the method to our optical imaging systems, the IVIS Lumina II to measure epifluorescence and the fluorescent molecular tomograph (FMT) for 3-dimensional quantification of the fluorophore. Epifluorescent imaging was performed 5-30 min after DBT injection which was followed by FMT imaging at 40 min. Two mice also underwent micro-CT imaging in the FMT cassette for the purpose of FMT-CT co-registration. Ex vivo imaging of the brain and other tissues of the head and neck was carried out 1 h after injection. Both the FMT-CT co-registration and the ex vivo imaging of organs proved that DBT poorly crossed the blood-brain barrier. The dye did not accumulate in the myelin sheath of the sciatic nerve. In contrast, there was an intense accumulation in the pituitary and salivary glands. The FMT-CT co-registration unequivocally demonstrated that the signal localized to the head did not originate from beyond the blood-brain barrier. No myelin binding was demonstrated by the ex vivo imaging either. In conclusion, DBT is unsuitable for in vivo imaging of myelination due to its poor BBB penetration, accumulation in other structures of the head and neck region and lack of selective binding towards myelin in vivo.

Topics: Animals; Benzothiazoles; Blood-Brain Barrier; Brain; Carbocyanines; Female; Fluorescent Dyes; Iodides; Male; Mice; Mice, Neurologic Mutants; Myelin Sheath; Nerve Fibers, Myelinated; Optical Imaging; Tomography, X-Ray Computed

Vibrational spectroscopy is a powerful analytical tool that assesses molecular properties based on spectroscopic signatures. In this study, the effect of gold nanoparticle morphology (spherical vs multi-branched) was assessed for the characterization of a Raman signal (ie, molecular fingerprint) that may be helpful for numerous medical applications. Multi-branched gold nanoparticles (MBAuNPs) were fabricated using a green chemistry method which employed the reduction of gold ion solute by 2-[4-(2-hydroxyethyl)-1-piperazyl] ethane sulfonic acid. Two types of reporter dyes, indocyanine (IR820 and IR792) and carbocyanine (DTTC [3,3'-diethylthiatricarbocyanine iodide] and DTDC [3,3'-diethylthiadicarbocyanine iodide]), were functionalized to the surface of the MBAuNPs and stabilized with denatured bovine serum albumin, thus forming the surface-enhanced Raman spectroscopy tag. Fluorescein isothiocyanate-conjugated anti-epidermal growth factor receptor to the surface-enhanced Raman spectroscopy tags and the properties of the resulting conjugates were assessed through determination of the Raman signal. Using the MBAuNP Raman probes synthesized in this manner, we demonstrated that MBAuNP provided significantly more surface-enhanced Raman scattering signal when compared with the associated spherical gold nanoparticle of similar size and concentration. MBAuNP enhancements were retained in the surface-enhanced Raman spectroscopy tags complexed to anti-epidermal growth factor receptor, providing evidence that this could be a useful biological probe for enhanced Raman molecular fingerprinting. Furthermore, while utilizing IR820 as a novel reporter dye linked with MBAuNP, superior Raman signal fingerprint results were obtained. Such results provide significant promise for the use of MBAuNP in the detection of numerous diseases for which biologically specific surface markers exist.

Topics: Antibodies; Benzothiazoles; Carbocyanines; ErbB Receptors; Fluorescein-5-isothiocyanate; Gold; Green Chemistry Technology; Indocyanine Green; Molecular Diagnostic Techniques; Molecular Probes; Nanoparticles; Serum Albumin, Bovine; Spectrum Analysis, Raman

From visible to mid-infrared frequencies, molecular sensing has been a major successful application of plasmonics because of the enormous enhancement of the surface electromagnetic nearfield associated with the induced collective motion of surface free carriers excited by the probe light. However, in the lower-energy terahertz (THz) region, sensing by detecting molecular vibrations is still challenging because of low sensitivity, complicated spectral features, and relatively little accumulated knowledge of molecules. Here, we report the use of a micron-scale thin-slab metamaterial (MM) architecture, which functions as an amplifier for enhancing the absorption signal of the THz vibration of an ultrathin adsorbed layer of large organic molecules. We examined bovine serum albumin (BSA) as a prototype large protein molecule and Rhodamine 6G (Rh6G) and 3,3'-diethylthiatricarbocyanine iodide (DTTCI) as examples of small molecules. Among them, our MM significantly magnified only the signal strength of bulky BSA. On the other hand, DTTCI and Rh6G are inactive, as they lack low-frequency vibrational modes in this frequency region. The results obtained here clearly demonstrate the promise of MM-enhanced absorption spectroscopy in the THz region for detection and structural monitoring of large biomolecules such as proteins or pathogenic enzymes.

Topics: Benzothiazoles; Carbocyanines; Proteins; Rhodamines; Serum Albumin, Bovine; Silicon; Silver; Terahertz Spectroscopy; Vibration

Myelination is one of the fundamental biological processes in the development of vertebrate nervous system. Disturbance of myelination is found to be associated with progression in many neurological diseases such as multiple sclerosis. Tremendous efforts have been made to develop novel therapeutic agents that prevent demyelination and/or promote remyelination. These efforts need to be accompanied by the development of imaging tools that permit direct quantification of myelination in vivo. In this work, we describe a novel near-infrared fluorescence imaging technique that is capable of direct quantification of myelination in vivo. This technique is developed based on a near-infrared fluorescent probe, 3,3'-diethylthiatricarbocyanine iodide (DBT) that readily enters the brain and specifically binds to myelinated fibers. In vivo imaging studies were first conducted in two animal models of hypermyelination and hypomyelination followed by longitudinal studies in the cuprizone-induced demyelination/remyelination mouse model. Quantitative analysis suggests that DBT is a sensitive and specific imaging probe of myelination, which complements other current myelin-imaging modalities and is of low cost.

Topics: Analysis of Variance; Animals; Benzothiazoles; Carbocyanines; Corpus Callosum; Cuprizone; Demyelinating Diseases; Disease Models, Animal; Longitudinal Studies; Mice; Mice, Inbred C57BL; Mice, Neurologic Mutants; Mice, Transgenic; Myelin Basic Protein; Myelin Proteolipid Protein; Myelin Sheath; Permeability; Protein Binding; Proto-Oncogene Proteins c-akt; Spectroscopy, Near-Infrared; Time Factors

Using UV-vis absorption and circular dichroism (CD) spectroscopies, we explored the binding interactions of 3,3'-diethylthiatricarbocyanine iodide (Cy7) with polynucleotides of different sequences and helicity. CD showed to be a very diagnostic tool giving different spectroscopic chiroptical signatures for all explored DNA sequences upon Cy7 binding. Cy7 was able to spectroscopically discriminate between the right handed B-DNA of poly(dG-dC)(2) and its left handed Z-DNA counterpart induced by spermine or Co(III)hexamine via nearly opposite induced circular dichroic signal.

Topics: Benzothiazoles; Carbocyanines; Circular Dichroism; DNA, B-Form; DNA, Z-Form; Polydeoxyribonucleotides; Protein Binding; Sequence Analysis, DNA; Structure-Activity Relationship

3.3'-Diethylthiatricarbocyanine iodide (DTTC) dye is an important infrared Raman probe molecule, and has received great attention in the past decades due to their potential applications in Raman imaging, single cell detection, and tumor marker. In the present work, ordinary Raman, surface enhanced Raman scattering (SERS), and theoretical Raman spectra were given to estimate the Raman spectrum of DTTC suspension. More specifically, the original gold nanospheres (60-nm diameter) and gold nanorods (NRs) were encoded with DTTC and stabilized with a layer of thiol-polyethylene glycol (PEG) as Raman reporter, and SERS data were obtained from the samples. Density functional theory (DFT) calculation was applied to calculate the optimized Raman spectra of DTTC water solvent on a B3LYP/6-31G level. Subsequently, the obtained experimental spectra from the DTTC were carefully compared with the theoretically calculated spectra. From the spectra comparation, good agreements were obtained between the theoretical and experimental results. This work will facilitate the development of ultrasensitive SERS probes for advanced biomedical applications.

Topics: Benzothiazoles; Carbocyanines; Gold; Spectrum Analysis, Raman; Sulfhydryl Compounds; Water

Near-infrared fluorescence tomography using molecularly targeted lifetime-sensitive, fluorescent contrast agents have applications for early-stage cancer diagnostics. Yet, although the measurement of fluorescent lifetime imaging microscopy (FLIM) is extensively used in microscopy and spectroscopy applications, demonstration of fluorescence lifetime tomography for medical imaging is limited to two-dimensional studies. Herein, the feasibility of three-dimensional fluorescence-lifetime tomography on clinically relevant phantom volumes is established, using (i) a gainmodulated intensified charge coupled device (CCD) and modulated laser diode imaging system, (ii) two fluorescent contrast agents, e.g., Indocyanine green and 3-3'-Diethylthiatricarbocyanine iodide differing in their fluorescence lifetime by 0.62 ns, and (iii) a two stage approximate extended Kalman filter reconstruction algorithm. Fluorescence measurements of phase and amplitude were acquired on the phantom surface under different target to background fluorescence absorption (70:1, 100:1) and fluorescence lifetime (1:1, 2.1:1) contrasts at target depths of 1.4-2 cm. The Bayesian tomography algorithm was employed to obtain three-dimensional images of lifetime and absorption owing to the fluorophores.

Topics: Algorithms; Bayes Theorem; Benzothiazoles; Breast; Carbocyanines; Fluorescent Dyes; Humans; Image Interpretation, Computer-Assisted; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Indocyanine Green; Lasers; Microscopy, Fluorescence; Phantoms, Imaging; Thiazoles; Time Factors; Tomography, Optical

To investigate fluorescence lifetime spectroscopy in tissue-like scattering, measurements of phase modulation as a function of modulation frequency were made using two fluorescent dyes exhibiting single exponential decay kinetics in a 2% intralipid solution. To experimentally simulate fluorescence multiexponential decay kinetics, we varied the concentration ratios of the two dyes, 3,3-diethylthiatricarbocyanine iodide and indocynanine green (ICG), which exhibit distinctly different lifetimes of 1.33 and 0.57 ns, respectively. The experimental results were then compared with values predicted using the optical diffusion equation incorporating 1) biexponential decay, 2) average of the biexponential decay, as well as 3) stretched exponential decay kinetic models to describe kinetics owing to independent and quenched relaxation of the two dyes. Our results show that while all kinetic models could describe phase-modulation data in nonscattering solution, when incorporated into the diffusion equation, the kinetic parameters failed to likewise predict phase-modulation data in scattering solutions. We attribute the results to the insensitivity of phase-modulation measurements in nonscattering solutions and the inaccuracy of the derived kinetic parameters. Our results suggest the high sensitivity of phase-modulation measurements in scattering solutions may provide greater opportunities for fluorescence lifetime spectroscopy.

Topics: Benzothiazoles; Calibration; Carbocyanines; Coloring Agents; Fluorescent Dyes; Indocyanine Green; Kinetics; Models, Statistical; Photons; Scattering, Radiation; Spectrometry, Fluorescence; Thiazoles; Time Factors

The cyanine dye DiS-C2-(5) was used to investigate the effect of K+ and glutamate receptor agonists on the membrane potential of whole populations of primary rat astrocytes in suspension. Increasing the external K+ concentration from 5 to 40 mM caused a depolarization of the cells. Ba2+ blocked the response to K+, whereas 4-aminopyridine had no effect on the depolarization. The effect of added external K+ was enhanced by the addition of the neutral K+ ionophore valinomycin. This supports the view that the membrane potential of primary astrocytes is dependent of the K+ gradient, and suggests that the membrane is not ideally permeable to K+ ions. Glutamate caused a depolarization of the cells which was not affected by Ba2+. In the presence of veratridine and ouabain no effect of glutamate was seen. The cells were also depolarized by the glutamate receptor agonists quisqualate, kainate and N-methyl-D-aspartate (NMDA). The response to kainate was blocked by kynurenate, which also diminished the depolarization caused by glutamate. NMDA was effective when added after kainate. The effect of the glutamate receptor agonists tested was generally smaller than that of glutamate itself, and a prior addition of one of the agonists diminished the response to glutamate. The results obtained suggest that cyanine dyes are well suited for investigating the behavior of whole populations of cultured primary astrocytes.

Topics: Animals; Astrocytes; Benzothiazoles; Brain; Carbocyanines; Cells, Cultured; Glutamates; Glutamic Acid; Kainic Acid; Membrane Potentials; Oxadiazoles; Potassium; Quisqualic Acid; Rats; Rats, Inbred Strains; Receptors, Glutamate; Receptors, Neurotransmitter; Thiazoles; Veratridine

Membrane potentials of particles present in a subcellular brain preparation, called synaptoneurosomes, have been monitored by measurement of changes in the absorbance of a cyanine dye, DiS-C2-5. The membrane potential of the particles seems to be dependent on both Cl- and K+ diffusion potentials, as judged from dependence of the absorbance changes on the K+ equilibrium potential across the membrane in the presence of Ba2+ or when Cl- was replaced with gluconate. The apparent high Cl- permeability of the membrane preparation was reduced in the presence of picrotoxin, a finding suggesting endogenous activation of receptor-linked Cl- channels. Glutamate and kainate caused depolarization of the membranes present in the preparation. This effect was only seen if K+ channels had been blocked in the presence of Ba2+ or 4-aminopyridine. No responses were observed with other glutamate receptor agonists (quisqualate or N-methyl-D-aspartate). The membrane potential of particles present in conventional synaptosomal preparations neither had a high Cl- permeability nor reacted to glutamate or kainate in the present conditions. The results suggest that synaptoneurosome preparations may be used for functional studies on postsynaptic neurotransmitter receptor-linked membrane potential changes with optical probes of membrane potential.

Topics: Animals; Benzothiazoles; Carbocyanines; Gramicidin; Membrane Potentials; Picrotoxin; Potassium; Quinolines; Quinuclidinyl Benzilate; Rats; Rats, Inbred Strains; Receptors, Glutamate; Receptors, Neurotransmitter; Synapses; Thiazoles; Valinomycin

The sensitivity of the fluorescent dye, 3,3'-diethylthiadicarbocyanine (DiS-C2(5], was too low for the detection of membrane potential changes in rat small intestinal membrane vesicles. Only after adding LaCl3 or after fractionation of the intestinal membranes by free-flow electrophoresis could the dye be used to monitor electrogenic Na+-dependent transport systems. It is concluded that the response of this potential-sensitive dye is influenced by the negative surface charge density of the vesicles.

Topics: Animals; Benzothiazoles; Carbocyanines; Cell Membrane; Fluorescent Dyes; Intestine, Small; Jejunum; Kidney Tubules, Proximal; Kinetics; Male; Membrane Potentials; Microvilli; Rats; Rats, Inbred Strains; Thiazoles

The accumulation of [3H]triphenylmethylphosphonium cation in neuroblastoma N1E 115 cells in the presence of tetraphenylboron is reduced by 3,3'-diethylthiadicarbocyanine iodide and by 3,3'-dipropylthiadicarbocyanine iodide. This reduction in uptake of the lipophilic cation is not due to the carbocyanine dyes depolarizing the plasma membrane of these cells but due to an interaction between the carbocyanine dyes and tetraphenylboron leaving less of the lipophilic anion free in solution to assist uptake of the lipophilic cation. This interaction is shown to have a 1:1 stoicheiometry.

Topics: Animals; Benzothiazoles; Biological Transport; Carbocyanines; Cell Line; Fluorescent Dyes; Indicators and Reagents; Kinetics; Membrane Potentials; Mice; Neoplasms, Experimental; Neuroblastoma; Onium Compounds; Quinolines; Thiazoles; Tritium; Trityl Compounds

A simple procedure for the preparation of dusting powders with a variety of fluorescent colors is described. Such powders permit detection of latent prints by laser even when the surfaces holding the latent prints luminesce strongly. A possible portable laser detection system is also suggested.

Topics: Aminoacridines; Benzothiazoles; Carbocyanines; Color; Dermatoglyphics; Fluorescent Dyes; Humans; Lasers; Luminescent Measurements; Oxazines; Powders; Rhodamines; Thiazoles