A combined small-angle neutron scattering (SANS) and X-ray (SAXS) study was conducted to investigate the structural characteristics of aqueous (D2O) solution generation 7 8 (G7 & G8) polyamidoamine (PAMAM) dendrimer as a function molecular protonation. consequent change in intramolecular conformation clearly quantified by detailed data analysis separating intermolecular correlations from contribution. Our results unambiguously reveal both an increase size continuous variation density profile...

Growing blackberries: The association of counterions around {Mo72V30} polyoxometalate macroanions increases with increasing macroion concentration and decreasing solvent polarity. counterion distribution extends about 2–9 Å from the surface highest probability at 2–3 surface. A close connection between self-assembly into "blackberry" structures is observed. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not...

We present a liquid-state theory for polyelectrolyte solutions. The predicts liquidlike structure on long length scales in dilute solution which disappears semidilute predictions of the static factor tobacco mosaic virus solutions are good agreement with light-scattering experiments both and Predictions scaling position maximum concentration consistent experiments.

The evaporation kinetics of droplets containing DNA was studied, as a function concentration. Drops very low concentrations dried by maintaining constant base, whereas those with high concentration contact angle. To understand this phenomenon, the distribution inside droplet measured using confocal microscopy. results indicated that condensed mostly on surface droplets. In case droplets, it formed shell, isolated islands were found for concentrations. Rheologic indicate formation hydro gel...

The properties of dilute and semidilute solutions rigid polyelectrolytes are investigated using integral equation theory. theory predicts liquidlike structure on length scales the order molecules in solution. This appears at concentrations much lower than overlap threshold concentration, disappears when concentration is sufficiently high. Liquidlike reappears higher a lengthscale thickness rods. predictions for static factor tobacco mosaic virus good agreement with light scattering...

A combined quasi-elastic neutron scattering (QENS) and high-resolution solution NMR spectroscopy study was conducted to investigate the internal dynamics of aqueous (D2O) G5 PAMAM dendrimer solutions as a function molecular protonation at room temperature. Localized motion segments clearly exhibited in QENS data analysis while global, center-of-mass translational diffusion measured by NMR. Our results unambiguously demonstrate an increased rapidity local scale (∼ 3 Å) upon increasing...

An accurate determination of the structure characteristics protonated generation 5 polyamidoamine dendrimers in aqueous solution has been conducted by analyzing small angle neutron scattering databased on a statistical mechanics model. In our investigation, primary focus is to elucidate effect counterion valence association and its impact intramolecular density profile within dendrimer. range study for molecular protonation, strong dependence structural properties charged revealed. Our...

Abstract We compared the effects of trivalent polyamines, spermidine (SPD) and norspermidine (NSPD), a chemical homologue SPD, on structure DNA gene expression. The structures SPD NSPD are different only with number methylene groups between amine groups, [N-3-N-4-N] [N-3-N-3-N], respectively. plays vital roles in cell function survival, including mammals. On other hand, has antitumor activity is found some species plants, bacteria algae, but not humans. that both polyamines exhibit biphasic...

The static structure of salt-free solutions rod-like polyelectrolyte is studied using Monte Carlo simulations and integral equations. polymer reference interaction site model theory with the Laria–Wu–Chandler closure found to be in good agreement for polyion–polyion counterion–counterion correlation functions, qualitative counterion–polyion functions. effect on polyion concentration counterion distribution important at low concentrations becomes more significant when Bjerrum length or degree...

Die Anlagerung von Gegenionen an makroionische {Mo72V30}-Polyoxometallate nimmt mit steigender Makroionen-Konzentration und sinkender Solvenspolarität zu. verteilen sich im Umkreis 2–9 Å um das Makroion, der höchsten Dichte bei 2–3 Entfernung Makroionenoberfläche (siehe Bild). Ein enger Zusammenhang zwischen Selbstorganistion {Mo72V30}-Moleküle in brombeerartige Strukturen wird beobachtet.

The Widom–Rowlinson mixture is a two component fluid where like species do not interact and unlike via hard core repulsion. As the density increased this phase separates. Using semigrand ensemble simulations finite size scaling we accurately locate critical at ρσ3=0.762±0.016 ρ total number σ sphere diameter. This much higher than previous estimates for model. We implement several integral equation theories, none of which are accurate point or coexistence curve.

A density functional theory is presented for the pair correlation functions in polymeric liquids. The uses Yethiraj–Woodward free-energy liquid, where ideal gas treated exactly and excess obtained using a weighted approximation with simplest choice of weighting function. Pair are Percus trick, external field taken to be single polymer molecule. minimization free energy requires two molecule simulation at each iteration. very accurate freely jointed tangent-hard-sphere chains rotating...

The static structure and conformational properties of salt-free polyelectrolyte solutions are studied using many-chain Monte Carlo simulations integral equations. polymer molecules modeled as freely jointed tangent sphere chains with a hard plus screened Coulomb potential between the beads. for most part in agreement previous molecular dynamics related model polymers but present work facilitates an unambiguous comparison theory simulation. An equation is implemented where obtained from...

An experimental scheme using contrast variation small angle neutron scattering technique is developed to investigate the structural characteristics of amine-terminated poly(amidoamine) dendrimers solutions. Using this methodology, we present dependence both intra-dendrimer water and polymer distribution on molecular protonation, which can be precisely adjusted by tuning pH solution. Assuming spherical symmetry spatial arrangement constituent components dendrimer, that atomic ratio...

Polyamines are involved in various biological functions, including cell proliferation, differentiation, gene regulation, etc. Recently, it was found that polyamines exhibit biphasic effects on expression: promotion and inhibition at low high concentrations, respectively. Here, we compared the of three naturally occurring tetravalent polyamines, spermine (SPM), thermospermine (TSPM), N4-aminopropylspermidine (BSPD). Based single DNA observation with fluorescence microscopy together...

A self-consistent integral equation theory is presented for the conformational behavior and static structure of polyelectrolyte solutions composed semiflexible chain molecules. The free energy solution expressed as sum an elastic, a Coulombic, medium-induced contribution, minimized with respect to single factor. In flexible limit, accurate conformations factor when compared Monte Carlo simulations chains. For chains near are sensitive bare persistence length in dilute but not semidilute...

The conformational behavior of isolated polyelectrolytes in poor solvents is investigated using theory and computer simulation. DiMarzio’s approach for the collapse transition neutral polymers extended to uniformly charged [E. A. diMarzio, Macromolecules 17, 969 (1984)]. predicts a discontinuous with decreasing solvent quality highly polymers. A also observed when charge fraction decreased very solvents. Monte Carlo simulations are reported lattice model polyelectrolytes. Under some...

The application of the spin-echo small angle neutron scattering (SESANS) technique for structural characterization interacting colloidal suspensions is considered in this work. framework to calculate theoretical SESANS correlation function briefly laid out. A general discussion regarding features functions obtained from different model systems presented. In comparison with conventional elastic tools operating at same length scale, our mean-field calculations, based on a monodisperse...

Spin-echo small angle neutron scattering (SESANS) provides a new experimental tool for structural investigation. Due to the action of spin-echo encoding, SESANS measures spatial correlation function in real space, as opposed structure factor S(Q), I(Q), momentum (Q) space measured by conventional scattering. To establish usefulness characterization, particularly interacting colloidal suspensions, we have previously conducted theoretical study functions model systems consisting particles with...

We conduct Monte Carlo simulations to understand the spatial distribution of a polymer molecule confined within rigid spherical capsule under crowding conditions, via bead-spring chain model. To adjust level, is mixed with crowders. As interior becomes more crowded, monomers tend move boundary penalty conformational entropy. By incorporating some attraction between and crowders, moves away from boundary. The interplay, entropy, DNA-protein interaction, molecular induced depletion force...

We have investigated the inhomogeneous interior of confined spherical cavities as capsules containing encapsulated binary hard sphere mixtures for different compositions and cavity wall rigidity. Such a greatly simplified model manifests effects macromolecular crowding arising from excluded volume interactions in tiny cell or cellular nucleus. By fixing number large particles, level is adjusted by changing amount small spheres cavity. For rigid cavity, tend to pack liquid-like order apart...

The structure of salt-free solutions tobacco mosaic virus particles is investigated using integral equations with the counterions incorporated explicitly. results for factor are identical to previous studies which used a Debye–Hückel approximation. explained model as polyacids.

We develop an experimental approach to analyze the water distribution around a core-shell micelle formed by polystyrene-block-poly[styrene-g-poly(ethylene oxide (PEO)] block copolymers in aqueous media at fixed polymeric concentration of 10 mg/ml through contrast variation small angle neutron scattering (SANS) study. Through varying D2O/H2O ratio, contributions from molecules and micellar constituent components can be determined. Based on commonly used model, theoretical coherent cross...