Enhanced electrorheological activity of porous chitosan particles.

Novel porous filler for electrorheological fluids was fabricated from chitosan via freeze drying technique. An exceptional electrorheological effect was discovered in suspensions of polydimethylsiloxane (silicone oil) filled by highly porous chitosan particles. The electrorheological activity was studied by rotational rheometry and visualized by optical microscopy. High porosity of the filler allows preparing highly efficient electrorheological fluids at rather low (< 1 wt%) concentration of dispersed phase. The mechanism of chain-like structure formation was considered. The electrorheological behavior of suspensions and the filler structural organization at different concentration were comprehended in terms of dielectric properties. The rheological data were approximated by Bingham and Cho-Choi-Jhon equations. The sedimentation stability of chitosan suspensions in polydimethylsiloxane was significantly affected by particles porosity.

Development prospects of curable osteoplastic materials in dentistry and maxillofacial surgery.

The article presents classification of the thermosetting materials for bone augmentation. The physical, mechanical, biological, and clinical properties of such materials are reviewed. There are two main types of curable osteoplastic materials: bone cements and hydrogels. Compared to hydrogels, bone cements have high strength features, but their biological properties are not ideal and must be improved. Hydrogels are biocompatible and closely mimic the extracellular matrix. They can be used as cytocompatible scaffolds for tissue engineering, as can protein- and nucleic acid-activated structures. Hydrogels may be impregnated with osteoinductors such as proteins and genetic vectors without conformational changes. However, the mechanical properties of hydrogels limit their use for load-bearing bone defects. Thus, improving the strength properties of hydrogels is one of the possible strategies to achieve the basis for an ideal osteoplastic material.

Experience of Antiseptic Application for Processing of Rat Lung Biological Matrices.

To select the optimum method for disinfecting scaffolds before recellularization, the effects of octenisept and chlorhexidine at different concentrations on lung biological matrices before and after decellularization were studied by using morphological methods (studies of biomechanical strength of extracellular matrix fibers) and by analyzing chemiluminescence in rats. Chlorhexidine diluted 1 : 10 had the least damage on the matrix properties and to the greatest extent contributed to disinfection of scaffolds for their further storage and experimental studies.

[Chitosan hydrogels biocompatibility improvement with the perspective of use as a base for osteoplastic materials in dentistry]. / Povyshenie biosovmestimosti khitozanovykh gidrogelei s perspektivoi ikh ispol'zovaniya v kachestve osnovy dlya kostno-plasticheskikh materialov v stomatologii.

Using chitosan as the basis for osteoplastic material, we were dealt with its low biocompatibility. The critical assessment of it is poorly presented in the literature and does not have systematic approaches to solving. The aim of the study was to determine the effect of factors affecting chitosan charge and its free amino groups number on the biocompatibility of hydrogels. Biocompatibility of chitosan compositions were studied in male Wistar rats (n=90). The subcutaneous implantation of chitosan discs and hydrogel caused abundant leukocyte infiltration. The addition of ß-glycerophosphate followed by dialysis slightly reduced the inflammatory response. Treatment with a solution of alkali NaOH and NaHCO3 buffer, on the contrary, intensified the inflammatory response. It is confirmed the effect of charged amino groups of chitosan on leukocyte taxis A decrease in the deacetylation degree (DD) of chitosan to 39.0% led to a statistically significant decrease in leukocyte infiltration. Saturation of chitosan hydrogels with PLA granules reduced by 16% the level of leukocyte infiltration, which was supposedly associated with a decrease in the volume of the hydrogel and an increase in the area of its interaction with blood plasma proteins, which reduce the positive charge of chitosan. The most significant reduction in leukocyte infiltration was achieved with a combination of deacetylated to 39.0% chitosan hydrogel with the addition of 16% by weight highly porous PLA granules.

[The prospects of hydrogels usage as a basis for curable osteoplastic materials]. / Perspektivy ispol'zovaniia gidrogelei v kachestve osnovy dlia otverzhdaemykh kostno-plasticheskikh materialov.

The article deals with the main types of the polymers used in hydrogel preparation. Their biological, physical and chemical properties was compared. Ways of polymers hardening and prospects of medical application were considered. The prospect of use of chitosan hydrogels activated by osteoinductors as a material for bone augmentation were concluded.

Evaluation of the influence of decellularization on the changes in biomechanical properties of primate lungs.

The effect of decellularization on the biomechanical properties of macaque lungs was studied. The quality of the biological scaffold was additionally assessed by morphological methods, and the contents of extracellular matrix (ECM) fibers were determined both qualitatively and quantitatively. Histological analysis revealed no damage of structural integrity of ECM components, but the scaffold elasticity significantly decreased, which was confirmed by the changes in the hysteresis loop without a concomitant decrease in peak loads, with the mechanical strength of the samples being retained. These changes require taking additional measures to prevent a decrease in the effective lung volume.