Utilization of optical polarization microscopy in the study of sorption characteristics of wound dressing host materials.

Polarization microscopy was used for evaluation of kinetics of diclofenac sorption in three different wound dressing materials. The sorption kinetics can be evaluated by radii change and intensity of the light traveling through the fiber. The most frequently used host materials for drugs in wound dressings are alginate, polyesters such as polyethylene terephthalate, and viscose. We studied sorption of diclofenac as an example drug. Effective, but rather simple in vitro simulation of diclofenac sorption gives insight into the applicability of the mentioned materials for development of wound healing materials.

The study of plasma's modification effects in viscose used as an absorbent for wound-relevant fluids.

Extreme non-equilibrium oxygen plasma was used for the deep functionalisation of viscose materials used for the healing of chronic wounds. Those thermal effects, which usually appear during plasma treatment due to the influence of charged particles, were avoided effectively by using electrode-less discharge at a very low power density of 25 W/l volume. A huge flux of neutrally reactive atoms at room temperature of 3x10(23)m(-2)s(-1), allowed for the effective diffusion of O-atoms into inter-fibril space and thus the activation of fibrils throughout the non-woven materials. Apart from the standard Wilhelmy balance and pedant drop method for determining the absorption dynamics on a macroscopic scale, optical polarisation microscopy was applied for studying the microscopic effects. The sorption characteristics were determined for saline solution, exudate, and blood and the results showed a dramatic improvement. Focusing on hydrophobic recovery prevention, the modified samples were stored for 10 days in air, nitrogen, and argon atmospheres. Some ageing effects occurred, whilst the absorption properties were independent of the storage atmosphere.

Liponucleoside thin films: the special behaviour of guanosine.

We performed a comparative study of self-assembling properties of liponucleoside materials containing different nucleobases in their hydrophilic headgroups, but possessing the same type of lipophilic moiety in their hydrophobic tails. Surface pressure versus area isotherms (π(A)) of monolayers formed at the air-water interface show that guanine-based materials form stable monolayer films exhibiting a profound first order phase transition from the liquid expanded to the condensed phase. Materials based on other nucleobases form less stable films exhibiting a liquid-like behaviour. Analysis of surface structures of Langmuir films with Brewster angle microscopy (BAM) and of Langmuir-Blodgett (LB) films deposited on mica surface by atomic force microscopy (AFM) confirms surface organization as resolved from the isotherms. The specific behaviour of molecules with a guanine head group is attributed to their optimal hydrophilic/hydrophobic balance, which is associated with the low water solubility of guanine derivatives.

Micropatterning of light-sensitive liquid-crystal elastomers.

We demonstrate that photoisomerizable liquid-crystal elastomer soft films can be used as tunable holographic gratings. Optomechanical mechanism of imprinting one-dimensional grating structure into the soft matrix by two-beam uv laser interference can be clearly resolved from the time dependence of the reading beam diffraction patterns. We analyze the observed response in terms of cis-trans isomerization-controlled modulation of the grating profile. The grating period can be tuned reversibly by stretching or contraction of the specimen, either thermomechanically or by applying external stress. Temperature-induced modifications of the grating parameters in the vicinity of the nematic-paranematic phase transition are also examined.