Navegando por Palavras-chave "DPPC"

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    Comparative study of liponucleosides in Langmuir monolayers as cell membrane models
    (Elsevier B.V., 2011-01-01) Montanha, E. A.; Caseli, L. [UNIFESP]; Kaczmarek, O.; Liebscher, J.; Huster, D.; Oliveira, O. N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Humboldt Univ; Univ Leipzig
    Liponucleosides may assist the anchoring of nucleic acid nitrogen bases into biological membranes for tailored nanobiotechnological applications. To this end precise knowledge about the biophysical and chemical details at the membrane surface is required. in this paper, we used Langmuir monolayers as simplified cell membrane models and studied the insertion of five lipidated nucleosides. These molecules varied in the type of the covalently attached lipid group, the nucleobase, and the number of hydrophobic moieties attached to the nucleoside. All five lipidated nucleosides were found to be surface-active and capable of forming stable monolayers. They could also be incorporated into dipalmitoylphosphatidylcholine (DPPC) monolayers, four of which induced expansion in the surface pressure isotherm and a decrease in the surface compression modulus of DPPC. in contrast, one nucleoside possessing three alkyl chain modifications formed very condensed monolayers and induced film condensation and an increase in the compression modulus for the DPPC monolayer, thus reflecting the importance of the ability of the nucleoside molecules to be arranged in a closely packed manner. the implications of these results lie on the possibility of tuning nucleic acid pairing by modifying structural characteristics of the liponucleosides. (C) 2010 Elsevier B.V. All rights reserved.
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    The interaction of mefloquine hydrochloride with cell membrane models at the air-water interface is modulated by the monolayer lipid composition
    (Elsevier B.V., 2014-10-01) Goto, Thiago Eichi [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The antiparasitic properties of antiparasitic drugs are believed to be associated with their interactions with the protozoan membrane, encouraging research on the identification of membrane sites capable of drug binding. in this study, we investigated the interaction of mefloquine hydrochloride, known to be effective against malaria, with cell membrane models represented by Langmuir monolayers of selected lipids. It is shown that even small amounts of the drug affect the surface pressure-area isotherms as well as surface vibrational spectra of some lipid monolayers, which points to a significant interaction. the effects on the latter depend on the electrical charge of the monolayer-forming molecules, with the drug activity being particularly distinctive for negatively charged lipids. Therefore, the lipid composition of the monolayer modulates the interaction with the lipophilic drug, which may have important implications in understanding how the drug acts on specific sites of the protozoan membrane. (C) 2014 Elsevier Inc. All rights reserved.
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    Interaction of oligonucleotide-based amphiphilic block copolymers with cell membrane models
    (Elsevier B.V., 2010-07-01) Caseli, L. [UNIFESP]; Pascholati, C. P.; Teixeira, F.; Nosov, S.; Vebert, C.; Mueeller, A. H. E.; Oliveira, O. N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Basel; Univ Bayreuth
    Oligonucleotides have unique molecular recognition properties, being involved in biological mechanisms such as cell-surface receptor recognition or gene silencing. for their use in human therapy for drug or gene delivery, the cell membrane remains a barrier, but this can be obviated by grafting a hydrophobic tail to the oligonucleotide. Here we demonstrate that two oligonucleotides, one consisting of 12 guanosine units (G(12)), and the other one consisting of five adenosine and seven guanosine (A(5)G(7)) units, when functionalized with poly(butadiene), namely PB-G(12) and PB-A(5)G(7), can be inserted into Langmuir monolayers of dipalmitoyl phosphatidyl choline (DPPC), which served as a cell membrane model. PB-G(12) and PB-A(5)G(7) were found to affect the DPPC monolayer even at high surface pressures. the effects from PB-G(12) were consistently stronger, particularly in reducing the elasticity of the DPPC monolayers, which may have important biological implications. Multilayers of DPPC and nucleotide-based copolymers could be adsorbed onto solid supports, in the form of Y-type LB films, in which the molecular-level interaction led to lower energies in the vibrational spectra of the nucleotide-based copolymers. This successful deposition of solid films opens the way for devices to be produced which exploit the molecular recognition properties of the nucleotides. (C) 2010 Elsevier Inc. All rights reserved.