Gaussian model of fluctuating membrane and its scattering properties.

A mathematical model is developed to jointly analyze elastic and inelastic scattering data of fluctuating membranes within a single theoretical framework. The model builds on a nonhomogeneously clipped time-dependent Gaussian random field. This specific approach provides one with general analytical expressions for the intermediate scattering function for any number of sublayers in the membrane and arbitrary contrasts.

MembraneDyn: simulating the dynamics of supported membrane stacks on the nanosecond timescale.

The static structure factor and the undulation dynamics of a solid-supported membrane stack have previously been calculated by Romanov and Ul'yanov [Romanov & Ul'yanov (2002). Phys. Rev.

Small-angle scattering for beginners.

Many experimental methods are available for the characterization of nanostructures, but most of them are limited by stringent experimental conditions. When it comes to analysing nanostructures in the bulk or in their natural environment - even as ordinary as water at room temperature - small-angle scattering (SAS) of X-rays or neutrons is often the only option. The rapid worldwide development of synchrotron and neutron facilities over recent decades has opened unprecedented possibilities for using SAS and in a time-resolved way.

Multiple scattering and resolution effects in small-angle neutron scattering experiments calculated and corrected by the software package .

This article deals with multiple scattering effects that are important for the method of small-angle neutron scattering (SANS). It considers three channels for the coherent elastic, the incoherent elastic and the incoherent inelastic scattering processes. The first channel contains the desired information on the experiment.

Inelastic neutron scattering analysis with time-dependent Gaussian-field models.

Converting neutron scattering data to real-space time-dependent structures can only be achieved through suitable models, which is particularly challenging for geometrically disordered structures. We address this problem by introducing time-dependent clipped Gaussian field models. General expressions are derived for all space- and time-correlation functions relevant to coherent inelastic neutron scattering for multiphase systems and arbitrary scattering contrasts.

Probing the Complex Loading-Dependent Structural Changes in Ultrahigh Drug-Loaded Polymer Micelles by Small-Angle Neutron Scattering.

Drug-loaded polymer micelles or nanoparticles are being continuously explored in the fields of drug delivery and nanomedicine. Commonly, a simple core-shell structure is assumed, in which the core incorporates the drug and the corona provides steric shielding, colloidal stability, and prevents protein adsorption. Recently, the interactions of the dissolved drug with the micellar corona have received increasing attention.

Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells.

Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs or many types of biological macromolecules, including DNA and proteins. Efficiency and speed of cargo delivery are especially high for carrier vesicles that fuse with the cellular plasma membrane. This occurs for lipid mixture containing equal amounts of the cationic lipid DOTAP and a neutral lipid with an additional few percents of an aromatic substance.

Long-range excitations in phospholipid membranes.

We investigated the existence of long-range excitations and correlated structures in phospholipid membranes by means of grazing-incidence neutron spin echo spectroscopy, grazing-incidence small-angle neutron scattering, and corresponding theoretical calculations inspired by smectic-membrane theory. All these methods confirmed the existence of thermal excitations in the plane of the surface of the phospholipid membranes or the corresponding structures, respectively. Also, these measurements revealed a temperature dependence of these excitations.

Nanoscale rheology at solid-complex fluid interfaces.

Here we present an approach to measure dynamic membrane properties of phospholipid membranes close to an interface. As an example we show results of the membrane dynamics of a phospholipid membrane multilayer-stack on a solid substrate (silicon). On this sample we were able to measure local interaction and friction parameters using Grazing Incidence Neutron Spin Echo Spectroscopy (GINSES), where an evanescent neutron wave probes the fluctuations close to a rigid interface.

A Thermogelling Supramolecular Hydrogel with Sponge-Like Morphology as a Cytocompatible Bioink.

Biocompatible polymers that form thermoreversible supramolecular hydrogels have gained great interest in biomaterials research and tissue engineering. When favorable rheological properties are achieved at the same time, they are particularly promising candidates as material that allow for the printing of cells, so-called bioinks. We synthesized a novel thermogelling block copolymer and investigated the rheological properties of its aqueous solution by viscosimetry and rheology.

Influence of ibuprofen on phospholipid membranes.

A basic understanding of biological membranes is of paramount importance as these membranes comprise the very building blocks of life itself. Cells depend in their function on a range of properties of the membrane, which are important for the stability and function of the cell, information and nutrient transport, waste disposal, and finally the admission of drugs into the cell and also the deflection of bacteria and viruses. We have investigated the influence of ibuprofen on the structure and dynamics of L-α-phosphatidylcholine (SoyPC) membranes by means of grazing incidence small-angle neutron scattering, neutron reflectometry, and grazing incidence neutron spin echo spectroscopy.

Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS: Different Behavior of Parallel and Perpendicular Lamellae.

The reorientation of lamellae and the dependence of the lamellar spacing, , on polymer volume fraction, ϕ, ∝ ϕ, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming poly(styrene--butadiene) prepared by spin-coating features lamellae of different orientations with the lamellar spacing depending on orientation. During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly.

Complex macrophase-separated nanostructure induced by microphase separation in binary blends of lamellar diblock copolymer thin films.

The nanostructures of thin films spin-coated from binary blends of compositionally symmetric polystyrene-b-polybutadiene (PS-b-PB) diblock copolymer having different molar masses are investigated by means of atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GISAXS) after spin-coating and after subsequent solvent vapor annealing (SVA). In thin films of the pure diblock copolymers having high or low molar mass, the lamellae are perpendicular or parallel to the substrate, respectively. The as-prepared binary blend thin films feature mainly perpendicular lamellae in a one-phase state, indicating that the higher molar mass diblock copolymer dominates the lamellar orientation.

Drug-induced morphology switch in drug delivery systems based on poly(2-oxazoline)s.

Defined aggregates of polymers such as polymeric micelles are of great importance in the development of pharmaceutical formulations. The amount of drug that can be formulated by a drug delivery system is an important issue, and most drug delivery systems suffer from their relatively low drug-loading capacity. However, as the loading capacities increase, i.