Biomedical subjects

Thomas Weigel

Publications and source records attributed to Thomas Weigel.

6 recordsLinked to original sources

PubMed2006

Poly(ether imide) membranes modified with poly(ethylene imine) as potential carriers for epidermal substitutes.

Poly(ether imide) (PEI) membranes were modified with a linear low-molecular weight (PETIM_0.6) and a branched high-molecular weight poly(ethylene imine) (PETIM_60). The membrane surfaces became more hydrophilic and the zeta potentials were shifted from negative to positive zeta values after immobilisation of both PETIM. These measurements also indicated the presence of a swollen surface layer in the case of PETIM_60, while a regular structuring of the surface was observed with scanning force microscopy for PETIM_0.6. A human keratinocyte cell line HaCaT was cultured on the different membranes. It was found that HaCaT cell growth was stimulated by PETIM_0.6. Cells reached earlier confluence on this substratum, while their growth was inhibited on a PEI membrane modified with PETIM_60, which makes PEI membranes modified with PETIM_0.6 a promising material for in vitro culture of epidermal transplants.

Adult↗

PubMed2006

Poly(ether imide) scaffolds as multifunctional materials for potential applications in regenerative medicine.

This article gives an overview of scaffolds that can be prepared from poly(ether imide) (PEI). These scaffolds were developed for extracorporeal blood detoxification processes in which specific compounds from blood or plasma are removed selectively. Both the preparation of porous microparticles and the preparation of hollow fibers are described. Commercially available particulate support materials have the disadvantage of a low accessibility of the internal pore system, a poor flow-through behavior and low adsorption specificity. Thus, novel support materials with optimally adapted properties profiles are needed. The second part of this article shows some recently developed highly asymmetric PEI hollow fibers. PEI scaffolds can be considered multifunctional because they combine separation characteristics, biocompatibility, sufficient biostability, and the possibility of creating tailor-made biofunctional surfaces.

Biocompatible Materials↗

PubMed2006

Inelastic scattering by particles of arbitrary shape.

The shape effect of inelastic scattering by small particles is investigated using geometrical optics. The particles considered are described by surfaces composed of triangles. In order to determine the accuracy of this model, the results for an approximated sphere with different degrees of discretization are compared with the result for a smooth sphere. The triangulation method is then used for describing a superellipsoid. This enables us to consider inelastic scattering for a variety of particles by changing only a few parameters.

Journal Article↗

PubMed2005

Inelastic scattering on particles with inclusions.

The investigation of particles with inclusions is of high interest in many parts of scientific research. Raman scattering is very good at yielding information on the internal composition of the particle. We use a geometrical-optics-based technique to determine the angle dependence of the inelastic scattering on particles with several spherical inclusions.

Journal Article↗

PubMed2004

Influence of polymer membrane porosity on C3A hepatoblastoma cell adhesive interaction and function.

The effect of the porosity of acrylonitrile-N-vinylpyrrolidone copolymer membranes on human C3A hepatoblastoma cell adhesive interaction and functioning is investigated on four membranes with an average pore size ranging between 6 and 12 nm. Adhesion of C3A cells was quantified and characterized by studying overall cell morphology and focal adhesion formation. Cell-cell interactions were characterized by E-cadherin expression and organization. Cell growth, fibronectin synthesis and cytochrome P450 activity were estimated as criteria of functional cell activity. The results suggest that membrane porosity influences the initial cell-surface interactions since an increasing pore size augmented cell adhesion and aggregate formation. Cell growth after 7 d was diminished on membranes with an average pore size of 12 nm. The activity of P450 measured by 7-ethoxycoumarin conversion at day 7 was influenced by membrane topography representing a clear optimum in the range of 7-10 nm pore size. These results indicate that membrane porosity is a determinant for the function of hepatocytes in extracorporal liver assist devices.

Cell Adhesion↗

PubMed2003

Online SAXS investigations of polymeric hollow fibre membranes.

Polymeric membranes are used in industrial and analytical separation techniques. In this study small-angle X-ray scattering (SAXS) with synchrotron radiation has been applied for in-situ characterisation during formation of polymeric membranes. The spinning of a polyetherimide (PEI) hollow fibre membrane was chosen for investigation of dynamic aggregation processes during membrane formation, because it allows the measurement of the dynamic equilibrium at different distances from the spinning nozzle. With this system it is possible to resolve structural changes in the nm-size range which occur during membrane formation on the time-scale of milliseconds. Integral structural parameters, like radius of gyration and pair-distance distribution, were determined. Depending on the chosen spinning parameters, e.g. the flow ratio between polymer solution and coagulant water, significant changes in the scattering curves have been observed. The data are correlated with the distance from the spinning nozzle in order to get information about the kinetics of membrane formation which has fundamental influence on structure and properties of the membrane.

Manufactured Materials↗