Investigations on the impact of the introduction of the Aloe vera into the hydrogel matrix on cytotoxic and hydrophilic properties of these systems considered as potential wound dressings.

In the paper, synthesis of chitosan-based hydrogels modified with Aloe vera juice is presented. The novelty of the research was a combination of hydrogel materials with properties beneficial in viewpoint of their use as modern wound dressings and Aloe vera juice supporting the wound healing process. Hydrogels have been obtained via UV radiation. The impact of the amount of the crosslinking agent as well as the introduction of the Aloe vera juice into the hydrogel matrix has been determined. Performed measurements involved analysis of the swelling ability, characteristics of the surface roughness, determining the release profile of Aloe vera and the contact angles of hydrogels. Furthermore, the analysis of the dehydration process of the polymer membrane, investigations on the cytotoxicity of hydrogels via MTT reduction assay and the neutral red uptake assay as well as the studies on the pro-inflammatory activity have also been performed. It was proved that the addition of Aloe vera juice improves the hydrophilic properties of the materials (e.g. contact angle changed from 82.5° to 73.0°). Next, the use of 25% more of the crosslinker resulted even in the increase of the contact angle by 86%. Modified hydrogels showed higher swelling properties even by 15% than unmodified materials. Furthermore, obtained hydrogels show an ability to release Aloe vera - after 5 h approx. 80% of this additive has been released in an acidic environment. Tested materials do not exhibit cytotoxic properties, the addition of Aloe vera results in an improvement of the viability of L929 murine fibroblasts and, importantly, these materials show lower pro-inflammatory activity than the positive control. Performed investigations allow to state that obtained materials show a great application potential.

Stabilization of ceramics particles with anionic polymeric dispersants.

The dispersion of colloidal ceramic particles in an aqueous media using a charged polymer has been investigated extensively. Most often, such a dispersion is obtained by an electrosteric mechanism. The stabilizing forces that result from electrical double layer repulsion and/or steric interaction must be sufficiently large in magnitude to provide an energy barrier against aggregation. Several factors, such as pH, temperature and ionic strength, nature, structure and molecular weight of the polyelectrolyte and its degree of dissociation can affect the respective contribution of electrostatic and steric interactions. In this study we applied silver nanoparticles prepared by reduction method with modifications. The hydroxyapatite was obtained from pork bone sludge. Polymer system contained poly(acrylic acid) and poly(ethylene glycol). The effects of dispersant structure on particle stabilization were investigated through properties of the suspensions. Viscosity and sedimentation height measurements indicated that addition of the dispersants improve particle stabilization. A dispersants were characterized using Scanning electron microscopy (SEM) with BSE detector (Back Scaterred Electrons), X-ray diffraction (XRD) and pH determination.