Cytocompatibility of surface ground PE doped with calcium salt of 6-carboxycellulose

We studied the physical–chemical properties of polyethylene (PE) films doped with calcium salt of 6-carboxycellulose (Ca-oxy) in concentrations 0–20 wt.% and their interactions with cells. The interaction between the PE/Ca-oxy composite film and 3T3 cells has not been described so far. Modification by surface grinding to enhance material cytocompatibility was studied. The surface wettability of doped films was tested by contact angle measurements and the surface morphology by SEM microscopy and profilometry. Adhesion and proliferation of tissue cells (3T3 mouse fibroblasts) were studied in vitro on pristine and ground doped PE films. The ground samples have a higher contact angle values and the number of proliferated cells is greater on the ground samples than on pristine ones. The presence of Ca-oxy in PE film increases the adhesion of 3T3 cells on the doped substrate and on ground samples adhere more cells than on pristine ones.

Towards a numerical simulation of a high temperature flow

Two mathematical models of unsteady plasma flows based on 3D finite volume methods for Navier‐Stokes equations are presented. In the first, cold jet model, the nondimensional NS equations are solved by the artificial compressibility method, and the results include time‐varying velocity fields for different Reynolds numbers. The second formulation is a compressible Stegger‐Warming flux vector splitting scheme that takes into account the non‐perfect character of the plasma fluid. Temperature and composition dependent gas properties are to be evaluated from real data.     

Cellulose-based materials as scaffolds for tissue engineering

Two types of cellulose-based materials, 6-carboxycellulose with 2.1 or 6.6 wt% of –COOH groups, were prepared and tested for potential use in tissue engineering. The materials were functionalized with arginine, i.e. an amino acid with a basic side chain, or with chitosan, in order to balance the relatively acid character of oxidized cellulose molecules, and were seeded with vascular smooth muscle cells (VSMC). The cell adhesion and growth were then evaluated directly on the materials, and also on the underlying polystyrene culture dishes. Of these two types of studied materials, 6-carboxycellulose with 2.1 wt% of –COOH groups was more appropriate for cell colonization. The cells on this material achieved an elongated shape, while they were spherical in shape on the other materials. The number of cells and the concentration (per mg of protein) of contractile proteins alpha-actin and SM1 and SM2 myosins, i.e. markers of the phenotypic maturation of VSMC, were also significantly higher on this material. Functionalization of the material with arginine and chitosan further improved the phenotypic maturation of VSMC. Chitosan also improved the adhesion and growth of these cells. In comparison with the control polystyrene dishes, the proliferation of cells on our cellulose-based materials was relatively low. This suggests that these materials can be used in applications where high proliferation activity of cells is not desirable, e.g. proliferation of VSMC on vascular prostheses. Alternatively, the cell proliferation might be enhanced by another more efficient modification, which would require further research.     

Evaluation and comparison of structurally different cellulose-based hemostatic agents in a rat kidney model

Different topical hemostatic materials are used to achieve effective hemostasis. High hemostatic activity, biocompatibility, bioresorbability, and easy manipulation are to be expected in such a developed product. In the surgical world with these specific requirements, finding a proper hemostatic agent is very difficult. The study compared several materials of various construction properties, which were assessed for structural and related properties by morphological analyses and assessed in vivo for their efficiency and behaviour using a model of rat partial nephrectomy. New sodium salt of carboxymethyl cellulose (CMC) sponge with the lowest porosity and free swell absorptive capacity contained the highest amount of hydroxyl and carboxyl groups. Results revealed that this CMC material in the form of a bioresorbable sponge may ensure the necessary hemostatic effects, while also providing a positive influence on the reaction of the local tissue. The CMC material also needed significantly less time to achieve hemostasis (p?<?0.001). Moreover, the sponge reached satisfactory results in the histopathological evaluation with the lowest destruction score and favorable healing reaction. This modified product proved itself to be a promising bioresorbable hemostat, which, according to its design, matches with its surgical applications. In general, the obtained data elucidated the dependency of the total effect on its structure and composition.

Graphic abstract