carbocyanines and cyanine-dye-1

Several classes of small organic molecules exhibit properties that make them suitable for fluorescence in vivo imaging. The most promising candidates are cyanines, squaraines, boron dipyrromethenes, porphyrin derivatives, hydroporphyrins, and phthalocyanines. The recent designing and synthetic efforts have been dedicated to improving their optical properties (shift the absorption and emission maxima toward longer wavelengths and increase the brightness) as well as increasing their stability and water solubility. The most notable advances include development of encapsulated cyanine dyes with increased stability and water solubility, squaraine rotaxanes with increased stability, long-wavelength-absorbing boron dipyrromethenes, long-wavelength-absorbing porphyrin and hydroporphyrin derivatives, and water-soluble phthalocyanines. Recent advances in luminescence and bioluminescence have made self-illuminating fluorophores available for in vivo applications. Development of new types of hydroporphyrin energy-transfer dyads gives the promise for further advances in in vivo multicolor imaging.

Topics: Carbocyanines; Fluorescent Dyes; Indoles; Isoindoles; Luminescence; Oxygen; Porphyrins; Solubility; Spectrometry, Fluorescence; Water

Macromolecular imaging probes (or sensors) of enzymatic activity have a unique place in the armamentarium of modern optical imaging techniques. Such probes were initially developed by attaching optically "silent" fluorophores via enzyme-sensitive linkers to large copolymers of biocompatible poly(ethylene glycol) and poly(amino acids). In diseased tissue, where the concentration of enzymes is high, the fluorophores are freed from the macromolecular carrier and regain their initial ability to fluoresce, thus allowing in vivo optical localization of the diseased tissue. This chapter describes the design and application of these probes and their alternatives in various areas of experimental medicine and gives an overview of currently available techniques that allow imaging of animals using visible and near-infrared light.

Topics: Amino Acids; Animals; Biosensing Techniques; Carbocyanines; Diagnostic Imaging; Disease Models, Animal; Enzymes; Fluorescence; Fluorescent Dyes; Humans; Macromolecular Substances; Mice; Neoplasm Transplantation; Polyethylene Glycols; Polymers; Spectroscopy, Near-Infrared

This report presents the synthesis and folate receptor target-specificity of amino-functionalized polyacrylamide nanoparticles (AFPAA NPs) for near-infrared (NIR) fluorescence imaging of cancer. For the synthesis of desired nano-constructs, the AFPAA NPs (hereafter referred to as NPs) were reacted with a NIR cyanine dye (CD) bearing carboxylic acid functionality by following our previously reported approach, and the resulting conjugate (NP-CD) on further reaction with folic acid (FA) resulted in a new nano-construct, FA-NP-CD, which demonstrated significantly higher uptake in folate receptor-positive breast cancer cells (KB+) and in folate receptor over-expressed tumors in vivo. The target-specificity of these nanoparticles was further confirmed by inhibition assay in folate receptor-positive (KB+) and -negative (HT-1080) cell lines. To show the advantages of polyacrylamide (PAA)-based NPs in folate receptor target-specificity, the CD used in preparing the FA-NP-CD construct was also reacted with folic acid alone and the synthetic conjugate (CD-FA) was also investigated for its target-specificity. Interestingly, in contrast to NPs (FA-NP-CD), the CD-FA conjugate did not show any significant in vitro or in vivo specificity toward folate receptors, showing the advantages of PAA-based nanotechnology in delivering the desired agent to tumor cells.

Topics: Acrylic Resins; Animals; Breast Neoplasms; Carbocyanines; Cell Line, Tumor; Female; Fibroblasts; Fibrosarcoma; Fluorescent Dyes; Folate Receptors, GPI-Anchored; Folic Acid; Glycoconjugates; Heterografts; Humans; Infrared Rays; KB Cells; Mice; Mice, Nude; Nanoparticles; Optical Imaging

To investigate whether new dyes and dye combinations can give equivalent or better staining in anterior capsule surgery than existing dyes with a low degree of toxicity on relevant cells.. University laboratory of Jacobs University Bremen, Germany.. Laboratory experimental study.. Pig eyes were collected post mortem. Cataract was induced by microwave irradiation. Access to the lens capsule was through open-sky surgery. Staining was performed and results were documented by photography. The toxicity of the dyes was evaluated in 3 different cell lines immediately after exposure and with a delay of 24 hours, with exposure in the dark or subsequent strong illumination.. A new cyanine dye, BIP (2-[5-[3,3-dimethyl-1-(4-sulfobutyl)-1,3-dihydro-indol-2-ylidene]-penta-1,3-dienyl]-3,3-dimethyl-1-(4-sulfobutyl)-3H-indolium sodium), was found to lead to green staining, with reduced toxicity on corneal endothelial cells. Staining could be further enhanced by combining it with trypan blue. Methylene blue was very toxic, whereas its combination with trypan blue was much less toxic.. With BIP alone or in combination with trypan blue, safe staining of the capsule can be achieved, resulting in a green color.

Topics: Animals; Anterior Capsule of the Lens; Capsulorhexis; Carbocyanines; Cataract; Coloring Agents; Disease Models, Animal; Swine; Trypan Blue

Visualization of DNA for fluorescence microscopy utilizes a variety of dyes such as cyanine dyes. These dyes are utilized due to their high affinity and sensitivity for DNA. In order to determine if the DNA molecules are full length after the completion of the experiment, a method is required to determine if the stained molecules are full length by digesting DNA with restriction enzymes. However, stained DNA may inhibit the enzymes, so a method is needed to determine what enzymes one could use for fluorochrome stained DNA. In this method, DNA is stained with a cyanine dye overnight to allow the dye and DNA to equilibrate. Next, stained DNA is digested with a restriction enzyme, loaded into a gel and electrophoresed. The experimental DNA digest bands are compared to an in silico digest to determine the restriction enzyme activity. If there is the same number of bands as expected, then the reaction is complete. More bands than expected indicate partial digestion and less bands indicate incomplete digestion. The advantage of this method is its simplicity and it uses equipment that a scientist would need for a restriction enzyme assay and gel electrophoresis. A limitation of this method is that the enzymes available to most scientists are commercially available enzymes; however, any restriction enzymes could be used.

Topics: Carbocyanines; DNA; DNA Restriction Enzymes; Fluorescent Dyes; Humans

Cyanine dyes are widely used in biological labeling and imaging because of their narrow near infrared emission, good brightness and high flexibility in functionalization, which not only enables multiplex analysis and multi-color imaging, but also greatly reduces autofluorescence from biological matter and increases signal-to-noise ratio. Unfortunately, their poor chemical- and photo-stability strongly limits their applications. The incorporation of cyanine dyes in silica nanoparticles provides a solution to the problem. On one hand, the incorporation of cyanine dyes in silica matrix can enhance their chemical- and photo-stability and increase brightness of the nanomaterials. On the other hand, silica matrix provides an optimized condition to host the dye, which helps to maintain their fluorescent properties during application. In addition, the well-established silane technique provides numerous functionalities for diverse applications. However, commercially available cyanine dyes are not very stable at high alkaline conditions, which will gradually lose their fluorescence over time. Our results showed that cyanine dyes are very vulnerable in the reverse micelle system, in which they will lose their fluorescence in less than half an hour. The existence of surfactant could greatly promote degradation of cyanine dyes. Fluorescent silica nanoparticles cannot be obtained at the high alkaline condition with the existence of surfactant. In contrast, the cyanine dyes are relatively stable in Stöber media. Owing to the fast formation of silica particles in Stöber media, the exposure time of cyanine dye in alkaline solution was greatly reduced, and highly fluorescent particles with good morphology and size distribution could be obtained via Stöber approach. However, the increasing water content in the Stöber could reduce the stability of cyanine dyes, which should be avoided. This research here provides a clear guidance on how to successfully synthesize cyanine dye-doped silica nanoparticles with good morphology, size distribution, stability and brightness.

Topics: Carbocyanines; Humans; Nanoparticles; Silicon Dioxide

Voltage-sensitive dyes (VSDs) are designed to monitor membrane potential by detecting fluorescence changes in response to neuronal or muscle electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo systems for external detection. By contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near-infrared light excitation and ultrasound detection. Here, we show that voltage-dependent quenching of dye fluorescence leads to a reciprocal enhancement of PA intensity. We synthesized a near-infrared photoacoustic VSD (PA-VSD), whose PA intensity change is sensitive to membrane potential. In the polarized state, this cyanine-based probe enhances PA intensity while decreasing fluorescence output in a lipid vesicle membrane model. A theoretical model accounts for how the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate PA voltage sensing but also emphasize the interplay of both fluorescence and absorbance properties in the design of optimized PA probes. Together, our results demonstrate PA sensing as a potential new modality for recording and external imaging of electrophysiological and neurochemical events in the brain.

Topics: Acoustics; Algorithms; Animals; Brain; Carbocyanines; Cell Membrane; Fluorescent Dyes; Humans; Membrane Lipids; Membrane Potentials; Microscopy, Fluorescence; Neurons; Phantoms, Imaging; Photoacoustic Techniques; Photons; Spectrometry, Fluorescence; Spectroscopy, Near-Infrared; Valinomycin

An RNA aptamer selected for binding to the fluorogenic cyanine dye, dimethylindole red (DIR), also binds and activates another cyanine, oxazole thiazole blue (OTB), giving two well-resolved emission colors. The aptamer binds to each dye with submicromolar K

Topics: Aptamers, Nucleotide; Carbocyanines; ErbB Receptors; Fluorescent Dyes; Microscopy, Confocal; Molecular Structure; Phantoms, Imaging; RNA

Endogenous hydrogen peroxide is an important parameter associated with cellular signal transduction and homeostasis. However, abnormal H2O2 regulation in live systems has been implicated in many pathological conditions. Monitoring this signal in live systems is essential but challenging because current H2O2 probes are impractical for efficient bio-imaging due to UV/visible light as the excitation source. We herein present a novel design based on an organic fluorophore-attached lanthanide-doped upconversion nanoprobe (CYD1-UCNPs) for selective UCL detection of H2O2. This nanoprobe represents the next-generation imaging tool that features a robust UCL "turn-on" response to H2O2 with NIR-excited ratiometric signals and has potential applications in ratiometric UCL imaging of endogenous H2O2 generating in living cells and whole-body animals.

Topics: Animals; Carbocyanines; Coloring Agents; Hydrogen Peroxide; Mice; Molecular Imaging; Molecular Probe Techniques; Molecular Probes; Nanoparticles; RAW 264.7 Cells; Spectroscopy, Near-Infrared

Non-covalent interaction of hemicyanine dyes, derivatives of 2,3,3-trimethyl-3H-indolium with bovine serum albumin has been studied by spectral method. For this purpose, three hemicyanine dyes containing N-(2-carboxyethyl)-2,3,3-trimethyl-3H-indolium moiety were synthesized and their UV/Vis and fluorescence spectra, aggregation, photostability and association with bovine serum albumin were studied. The hemicyanine dyes with 2-ethylcarboxylic group was found to interact with bovine serum albumin, which is probably due to negative charge on the dye molecule at the expense of the carboxylic group and the ability to form hydrogen bonds with albumin.

Topics: Albumins; Animals; Carbocyanines; Carboxylic Acids; Cattle; Chromatography, Thin Layer; Coloring Agents; Fluorescent Dyes; Hydrogen Bonding; Indoles; Magnetic Resonance Spectroscopy; Oxidation-Reduction; Photochemistry; Serum Albumin, Bovine; Solvents; Spectrometry, Fluorescence; Temperature

We report a supramolecular approach for the preparation of photostable NIR nanovesicles based on a cyanine dye derivative as a photoacoustic (PA) contrast agent for high-performance nano-imaging.

Topics: Animals; Carbocyanines; Contrast Media; Drug Stability; Heterografts; Humans; Light; Mice; Molecular Structure; Nanotechnology; Neoplasms; Photoacoustic Techniques; Radiography; Spectroscopy, Near-Infrared

A supramolecular probe for visual detection of mercury (Hg) has been designed by using a cyanine dye and AS1411 G-quadruplexes, which exhibits an obvious color change from red to blue in response to an increased level of Hg(2+). The supramolecular probe exhibits high selectivity and sensitivity towards Hg(2+) and is promising for the detection of environmental samples with the naked eye.

Topics: Biosensing Techniques; Carbocyanines; Circular Dichroism; Colorimetry; Coloring Agents; Environmental Monitoring; Fresh Water; G-Quadruplexes; Macromolecular Substances; Mercury; Potassium; Reproducibility of Results; Water Pollutants, Chemical

Demarking lymph node networks is important for cancer staging in clinical practice. Here, we demonstrate in vivo dual-color photoacoustic lymphangiography using all-organic nanoformulated naphthalocyanines (referred to as nanonaps). Nanonap frozen micelles were self-assembled from two different naphthalocyanine dyes with near-infrared absorption at 707 nm or 860 nm. These allowed for noninvasive, nonionizing, high resolution photoacoustic identification of separate lymphatic drainage systems in vivo. With both types of nanonaps, rat lymph nodes buried deeply below an exogenously-placed 10 mm thick layer of chicken breast were clearly visualized in vivo. These results show the potential of multispectral photoacoustic imaging with nanonaps for detailed mapping of lymphatic drainage systems.

Topics: Acoustics; Animals; Breast Neoplasms; Carbocyanines; Cell Movement; Chickens; Color; Female; Humans; Lymph Nodes; Mice; Mice, Inbred BALB C; Micelles; Nanoparticles; Nanotechnology; Neoplasm Metastasis; Neoplasm Staging; Optics and Photonics; Rats; Rats, Sprague-Dawley; Sentinel Lymph Node Biopsy; Spectrophotometry

A Se-containing heptamethine cyanine dye based fluorescent probe was successfully developed and used for HClO detection with rapid response and high selectivity based on aggregation behavior. The probe could react with HClO with significant change in its fluorescence profile, which makes it practical for detecting HClO in fetal bovine serum and in living mice.

Topics: Animals; Carbocyanines; Cattle; Crystallography, X-Ray; Fluorescent Dyes; Hypochlorous Acid; Mice; Mice, Nude; Molecular Conformation; Selenium; Spectroscopy, Near-Infrared

Molecular recognition of DNA quadruplex structures is envisioned to be a strategy for regulating gene expression at the transcriptional level and for in situ analysis of telomere structure and function. The recognition of DNA quadruplexes by peptide nucleic acid (PNA) oligomers is presented here, with a focus on comparing complementary, heteroduplex-forming and homologous, heteroquadruplex-forming PNAs. Surface plasmon resonance and optical spectroscopy experiments demonstrated that the efficacy of a recognition mode depended strongly on the target. Homologous PNA readily invades a quadruplex derived from the promoter regulatory region found upstream of the MYC proto-oncogene to form a heteroquadruplex at high potassium concentration mimicking the intracellular environment, whereas complementary PNA exhibits virtually no hybridization. In contrast, complementary PNA is superior to the homologous in hybridizing to a quadruplex modeled on the human telomere sequence. The results are discussed in terms of the different structural morphologies of the quadruplex targets and the implications for in vivo recognition of quadruplexes by PNAs.

Topics: Binding Sites; Carbocyanines; Circular Dichroism; DNA, Complementary; G-Quadruplexes; Humans; Molecular Structure; Nucleic Acid Hybridization; Peptide Nucleic Acids; Proto-Oncogene Mas; Sequence Homology, Nucleic Acid

Two-photon-pumped dye lasers are very important because of their applications in wavelength up-conversion, optical data storage, biological imaging and photodynamic therapy. Such lasers are very difficult to realize in the solid state because of the aggregation-caused quenching. Here we demonstrate a new two-photon-pumped micro-laser by encapsulating the cationic pyridinium hemicyanine dye into an anionic metal-organic framework (MOF). The resultant MOF [symbol: see text] dye composite exhibits significant two-photon fluorescence because of the large absorption cross-section and the encapsulation-enhanced luminescent efficiency of the dye. Furthermore, the well-faceted MOF crystal serves as a natural Fabry-Perot resonance cavity, leading to lasing around 640 nm when pumped with a 1064-nm pulse laser. This strategy not only combines the crystalline benefit of MOFs and luminescent behaviour of organic dyes but also creates a new synergistic two-photon-pumped lasing functionality, opening a new avenue for the future creation of solid-state photonic materials and devices.

Topics: Absorption; Carbocyanines; Coloring Agents; Crystallization; Fluorescence; Lasers; Light; Luminescence; Metals; Microscopy, Confocal; Microscopy, Fluorescence; Optics and Photonics; Photochemotherapy; Photons; Pyridines

Triclosan is a biocidal active agent commonly used in domestic and industrial formulations. Currently, there is limited understanding of the mechanisms involved in triclosan tolerance in Escherichia coli O157. The aim of this study was to identify the differences between a triclosan susceptible E. coli O157:H19 isolate (minimum inhibitory concentration; MIC 6.25 μg/ml) and its triclosan tolerant mutant (MIC>8000 μg/ml) at a proteomic and phenotypic level. Two dimensional DIGE was used to identify differences in protein expression between the reference strain and triclosan tolerant mutant in the presence and absence of triclosan. DIGE analysis indicates the proteome of the reference E. coli O157:H19 was significantly different to its triclosan tolerant mutant. Significant changes in protein expression levels in the triclosan tolerant mutant included the known triclosan target FabI which encodes enoyl reductase, outer membrane proteins and the filament structural protein of flagella, FliC. Phenotypic studies showed that the triclosan tolerant mutant MIC decreased in the presence of efflux inhibitor phenyl-arginine-β-naphthylamide and biofilm formation was increased in the mutant strain. The data generated indicates that enhanced triclosan tolerance is a result of multiple mechanisms which act together to achieve high-level resistance, rather than mutation of FabI alone.

Topics: Acyl-CoA Dehydrogenases; Bacterial Adhesion; Biofilms; Caco-2 Cells; Carbocyanines; Cellulose; Dipeptides; Drug Resistance, Bacterial; Electrophoresis, Gel, Two-Dimensional; Escherichia coli O157; Gene Expression Profiling; Humans; Immunoblotting; Mass Spectrometry; Microbial Sensitivity Tests; Mutation; Oxidoreductases; Phenotype; Proteome; Proteomics; Triclosan

β-Nicotinamide adenine dinucleotide (NAD(+)) and its reduced form NADH specifically interact with a cyanine dye in aqueous media, giving distinct spectral and nanostructural characteristics to which molecular information of constituent coenzymes are converted via self-assembly.

Topics: Carbocyanines; Coenzymes; NAD; Nanofibers; Nanoparticles; Oxidation-Reduction

Mitochondrial membrane potential provides a valuable indicator of cells' health and functional status. Cytometry- and microscopy-based analyses, in combination with fluorescent probes, are widely used to study mitochondrial behavior related to cellular pathways, most notably - apoptosis. The cyanine dye JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimi- dazolylcarbocyanine iodide) facilitates discrimination of energized and deenergized mitochondria because the normally green fluorescent dye forms red fluorescent aggregates when concentrated in energized mitochondria in response to their higher membrane potential. JC-1 fluorescence is usually excited by the 488 nm laser wavelength common in flow cytometers. In this study, we show that in practice this approach is not optimal for monitoring mitochondrial behavior. Investigation of fluorescence of JC-1 in solution and in cells using spectrofluorimetry, microscopy and flow cytometry reveals that excitation at 405 nm wavelength, now available on standard instruments, produces signals from aggregate fluorescence with considerably less spillover from dye monomer fluorescence than can be obtained using 488 nm excitation. The improved data are more accurate and eliminate the necessity for fluorescence compensation, making the use of the alternative excitation wavelengths beneficial for mitochondria-related biological and biomedial research.

Topics: Animals; Apoptosis; Carbocyanines; Cells; Flow Cytometry; Fluorescent Dyes; HeLa Cells; Humans; Membrane Potential, Mitochondrial; Mice; Mitochondria

A sensitive fluorescence quantitative determination for bovine serum albumin (BSA) or human serum albumin (HSA) has been developed by using a new hydrophilic cyanine dye 1, 1'-sulfonopropyl-3,3,3', 3'-tetramethylindolium-5,5'-disulfonic potassium (STDP) as a fluorescence probe. Using BSA as a representative protein, characteristics of the fluorescence reaction of STDP with protein were investigated. Effects of the concentration of the hydrophilic cyanine dye, pH value of the buffer solution, and ion-intensity of NaCl were also studied as well as the ratio of ethanol. In the citrate-HCl buffer solution, the fluorescence emission wavelength of BSA-STDP system was 562 nm with the maximum excitation wavelength of 548 nm, and the Stokes displacement was 14 nm. With the pH ranging from 1.0 to 2.0, the fluorescence was increasing and up to the maximum at pH 2.0. However, in the pH range of 3.0-5.0, the interaction of BSA and STDP was weakened due to the decrease in positive charge on the BSA chain, which resulted in an observable decrease of the enhancement of the fluorescence intensity. At the optimum pH of 2.0, electrostatic interactions of positive charges of the BSA chain and negative charges on the sulfonic groups of STDP were carried out. The interactions of the indole group of STDP and some active groups of BSA (viz. amido, carboxyl or sulfhydryl) were also achieved, and resulted in the combination of indole group of cyanine dye into the chain of BSA. So the hydrophobic effect and the protection provided by the skeleton chain of BSA were both improved to prevent the fluorescent energy of STDP from losing in the solution, which caused a notable fluorescence increase with an observable shift to the longer emission wavelength. Furthermore, with the augmentation of BSA, the alpha-helix structure of BSA molecular turned from the unwrapped state to the enfolded state, in favor of restraining free-oscillation of fluorescence probe in the solution and maintaining a high energy transfer efficiency. Such a fact fueled a highly enhancement of the fluorescence too. Besides, effects of the concentration of cyanine dye on the determination of BSA were also investigated. The fluorescence intensity (DeltaF) was enhanced with the increase in the quantity of STDP and gained the peak at 1.00 micromol x L(-1). However, when STDP ranged from 1.50 to 5.00 micromol x L(-1), some negative congregate effects on the nature of cyanine dye might happen and resulted in a too high flu

Topics: Animals; Carbocyanines; Cattle; Fluorescent Dyes; Humans; Protein Binding; Serum Albumin; Spectrometry, Fluorescence

The J-aggregation of Cyanine-1dye in the presence of carboxymethyl amylose (CMA) is described. The J-aggregation requires a large excess CMA concentration; the J-band maximum appears in the concentration range, [CMA]/[dye] = 10-50, depending on the degree of substitution (DS) of carboxylation, where [CMA] is the concentration of polymer repeat units. An extraordinarily large induced circular dichroism (CD) is observed from J-aggregates of the achiral cyanine dye in association with a random coil CMA, suggesting that the CMA is transformed into a helix. The magnitude of CD intensity increases with increasing DS of CMA and pH up to neutral (where a maximum J-aggregation occurs), while the CMA-bound dye monomer and H-aggregates (occurring at pH > or = 9) exhibit no induced CD. The trend in the CD intensity (of the J-aggregates) is in parallel with the fluorescence intensity of the J-aggregates. This suggests that binding of the J-aggregates onto the template CMA is sterically controlled by the asymmetric environment of glucose residues (of CMA) so that more twisting power is exerted with increasing DS (of CMA), rendering the cyanine dye/CMA complex a more rigid (a high fluorescence intensity) super-helix. This is also revealed by the AFM image of a long strand.

Topics: Amylose; Carbocyanines; Carbohydrate Conformation; Circular Dichroism; Hydrogen-Ion Concentration; Kinetics; Microscopy, Atomic Force; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet

The origin of the cyanine dye fluorescence signal in murine and human peripheral blood leukocytes was investigated using the oxa- and indo-carbocyanines di-O-C5(3) and di-I-C5(3). Fluorescence signals from individual cells suspended with nanomolar concentrations of the dyes were measured in a flow cytometer modified to permit simultaneous four-parameter analysis (including two-color fluorescence or fluorescence polarization measurements). The contributions of mitochondrial membrane potential (psi m) and plasma membrane potential (psi pm) to the total voltage-sensitive fluorescence signal were found to depend on the equilibrium extracellular dye concentration, manipulated in these experiments by varying the ratio of dye to cell density. Hence, conditions could be chosen that amplified either the psi m or the psi pm component. Selective depolarization of lymphocytes or polymorphonuclear leukocytes (PMN) in mixed cell suspensions demonstrated that defining the partition of dye between cells and medium is requisite to assessing the heterogeneity of cell responses by cyanine dye fluorescence. At extracellular dye concentrations exceeding 5 nM in equilibrated cell suspensions, both mitochondrial and plasma membrane dye toxicity were observed. In murine splenic lymphocytes, plasma membrane toxicity (dye-induced depolarization) was selective for the B lymphocytes. Certain problems in calibration of psi pm with valinomycin at low dye concentrations and perturbations of psi pm by mitochondrial inhibitors are presented. These findings address the current controversy concerning psi m and psi pm measurement in intact cells by cyanine dye fluorescence. The finding of selective toxicity at low cyanine dye concentrations suggest that purported differences in resting psi m among cells or changes in psi pm with cell activation may reflect variable susceptibility to dye toxicity rather than intrinsic cell properties.

Topics: B-Lymphocytes; Carbocyanines; Cell Membrane; Cell Membrane Permeability; Culture Media; Electrophysiology; Fluorescent Dyes; Humans; Ion Channels; Lymphocytes; Mathematics; Mitochondria; Potassium; Quinolines; Rubidium; Sodium-Potassium-Exchanging ATPase; Valinomycin