Planar nanosystems on the basis of complexes formed by amphiphilic polyamine, magnetite nanoparticles, and DNA molecules

Kim, V. P.; Ermakov, А. V.; Glukhovskoy, E. G.; Rakhnyanskaya, A. A.; Gulyaev, Yu. V.; Черепенин, В. А.; Taranov, I. V.; Kormakova, P.A.; Potapenkov, K.V.; Usmanov, N. N.; Saletsky, A. M.; Koksharov, Yu. A.; Хомутов, Г.Б.

doi:10.1134/s1995078014030070

Cited by 6 publications

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“…There are many examples for such shoulders and their interpretation in terms of orientational changes. Cyclosporin A [ 21 ], amphotericin B [ 22 , 23 ], nystatin [ 24 ], stearylspermine [ 25 ], monoacylated

-cyclodextrins [ 26 ], cholesterol derivatives such as 7

-hydroxycholesterol [ 27 ] or oxysterol [ 28 , 29 ], carboxylic acid with a symmetrical triphenylbenzene ring system [ 30 ], certain dumbbell-like molecules like amphiphilic bistable rotaxanes [ 31 ] or polyoxometalate (POM)-based inorganic–organic–inorganic molecular hybrids [ 32 ], tri-podal amphiphiles [ 33 ], and alpha-helical peptides [ 34 , 35 , 36 ] have all been reported to undergo orientational adjustments—typically between two orientations—when being used as surface-active molecules in Langmuir monolayers at varying lateral pressure. Other examples include organic–inorganic nanoparticles such as derivatives of varying amphiphilicity of fully condensed polyhedral oligomeric silsesquioxanes (POSS) [ 37 ], matrix organosilane amphiphiles (and also mixed monolayers of vitamin

mimics with these organosilane amphiphiles) [ 38 ], and organic–inorganic hybrid molecular films consisting of a Keggin-type polyoxometalate PW

and a series of gemini amphiphiles with various lengths of the flexible spacers [ 39 ].…”

Section: Introductionmentioning

confidence: 99%

Incorporation of Molecular Reorientation into Modeling Surface Pressure-Area Isotherms of Langmuir Monolayers

2021

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Langmuir monolayers can be assembled from molecules that change from a low-energy orientation occupying a large cross-sectional area to a high-energy orientation of small cross-sectional area as the lateral pressure grows. Examples include cyclosporin A, amphotericin B, nystatin, certain alpha-helical peptides, cholesterol oxydation products, dumbbell-shaped amphiphiles, organic–inorganic nanoparticles and hybrid molecular films. The transition between the two orientations leads to a shoulder in the surface pressure-area isotherm. We propose a theoretical model that describes the shoulder and can be used to extract the energy cost per molecule for the reorientation. Our two-state model is based on a lattice–sublattice approximation that hosts the two orientations and a corresponding free energy expression which we minimize with respect to the orientational distribution. Inter-molecular interactions other than steric repulsion are ignored. We provide an analysis of the model, including an analytic solution for one specific lateral pressure near a point of inflection in the surface pressure-area isotherm, and an approximate solution for the entire range of the lateral pressures. We also use our model to estimate energy costs associated with orientational transitions from previously reported experimental surface pressure-area isotherms.

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