Circular dichroism microscopy of compact forms of DNA and chromatin in vivo and in vitro: cholesteric liquid-crystalline phases of DNA and single dinoflagellate nuclei

Light microscopy is a convenient technique for characterizing molecular order in fluid liquid crystalline materials. Microstructures can usually be observed under the actual conditions that promote the formation of liquid crystalline phases, whether or not a solvent is required, and at temperatures that can range from the boiling point of nitrogen to 600°C. It is relatively easy to produce specimens that are sufficiently thin and flat, simply by confining a droplet between glass cover slides. Specimens do not need to be conducting, and they do not have to be maintained in a vacuum. Drybox or other controlled environmental conditions can be maintained in a sealed chamber equipped with transparent windows; some heating/ freezing stages can be used for this purpose. It is relatively easy to construct a modified stage so that the generation and relaxation of global molecular order can be observed while specimens are being sheared, simulating flow conditions that exist during processing. Also, light only rarely affects the chemical composition or molecular weight distribution of the sample. Because little or no processing is required after collecting the sample, one can be confident that biologically derived materials will reveal many of their in vivo structural characteristics, even though microscopy is performed in vitro.

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Enantioselective cholesteric liquid crystalline membranes characterized using nonchiral HPLC with circular dichroism detection

Journal of Membrane Science ◽

10.1016/j.memsci.2010.09.039 ◽

2011 ◽

Vol 367 (1-2) ◽

pp. 1-6 ◽

Cited By ~ 7

Author(s):

Sangil Han ◽

Stephen M. Martin

Keyword(s):

Circular Dichroism ◽

Liquid Crystalline ◽

Circular Dichroïsm ◽

Cholesteric Liquid Crystalline

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Effect of pendant chiral groups on the induction of cholesteric liquid crystalline phases

10.1117/12.813597 ◽

2009 ◽

Author(s):

Jui-Hsiang Liu ◽

Feng-Ming Hsieh

Keyword(s):

Liquid Crystalline ◽

Crystalline Phases ◽

Liquid Crystalline Phases ◽

Cholesteric Liquid Crystalline

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Fluorescence-detected circular dichroism of ethidium in vivo and bound to deoxyribonucleic acid in vitro

Biochemistry ◽

10.1021/bi00333a001 ◽

1985 ◽

Vol 24 (12) ◽

pp. 2819-2822 ◽

Cited By ~ 5

Author(s):

Michael L. Lamos ◽

Douglas H. Turner

Keyword(s):

Circular Dichroism ◽

Deoxyribonucleic Acid ◽

Circular Dichroïsm

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Peptides of pHLIP family for targeted intracellular and extracellular delivery of cargo molecules to tumors

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1715350115 ◽

2018 ◽

Vol 115 (12) ◽

pp. E2811-E2818 ◽

Cited By ~ 38

Author(s):

Linden C. Wyatt ◽

Anna Moshnikova ◽

Troy Crawford ◽

Donald M. Engelman ◽

Oleg A. Andreev ◽

...

Keyword(s):

Circular Dichroism ◽

Targeted Delivery ◽

Tumor Imaging ◽

Intracellular Delivery ◽

Membrane Lipid ◽

Wide Range ◽

Ph Dependent ◽

Circular Dichroïsm

The pH (low) insertion peptides (pHLIPs) target acidity at the surfaces of cancer cells and show utility in a wide range of applications, including tumor imaging and intracellular delivery of therapeutic agents. Here we report pHLIP constructs that significantly improve the targeted delivery of agents into tumor cells. The investigated constructs include pHLIP bundles (conjugates consisting of two or four pHLIP peptides linked by polyethylene glycol) and Var3 pHLIPs containing either the nonstandard amino acid, γ-carboxyglutamic acid, or a glycine−leucine−leucine motif. The performance of the constructs in vitro and in vivo was compared with previous pHLIP variants. A wide range of experiments was performed on nine constructs including (i) biophysical measurements using steady-state and kinetic fluorescence, circular dichroism, and oriented circular dichroism to study the pH-dependent insertion of pHLIP variants across the membrane lipid bilayer; (ii) cell viability assays to gauge the pH-dependent potency of peptide-toxin constructs by assessing the intracellular delivery of the polar, cell-impermeable cargo molecule amanitin at physiological and low pH (pH 7.4 and 6.0, respectively); and (iii) tumor targeting and biodistribution measurements using fluorophore-peptide conjugates in a breast cancer mouse model. The main principles of the design of pHLIP variants for a range of medical applications are discussed.

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