Beata Kaczmarek

Characterization of chitosan composites with various clays

The structural properties, thermal behaviour and mechanical properties of composites of chitosan (Ch) with nanoclay (montmorillonite, MMT) and/or nanoclays after surface modification have been characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and a tensile tests. The microstructure obtained by SEM and AFM microscopy for unmodified chitosan and its composites showed that particles are relatively well dispersed in the chitosan matrix. However, the increasing concentration of the chitosan solution from 1% to 2% decreases the homogeneity of the surface of the composites. In the case of chitosan composite with modified nanoclay (contains 25-30 wt.% of octadecylamine), the lack of particles aggregates in polymer matrix independent of the concentration of chitosan solution was observed. Generally, addition of nanoclay after its surface modification improved the mechanical and thermal properties of the composite much more than montmorillonite without modification.

3D composites based on the blends of chitosan and collagen with the addition of hyaluronic acid

3D porous composites based on blends of chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Mechanical properties, swelling behavior and thermal stability of the blends were studied. Moreover, SEM images were taken and the structure of the blends was studied. Biological properties of the materials obtained were investigated by analyzing of proliferation rate of fibroblast cells incubated with biomaterial extract using MTT assay (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide). The results showed that the properties of 3D composites based on the blends of chitosan and collagen were altered after the addition 1%, 2% and 5% of hyaluronic acid. Mechanical properties and thermal stability of chitosan/collagen blends were improved in the presence of hyaluronic acid in the composite. New 3D materials based on the blends of chitosan, collagen and hyaluronic acid were non-toxic and did not significantly affect cell morphology.

The influence of UV-irradiation on chitosan modified by the tannic acid addition.

The influence of UV-irradiation with the wavelength 254 nm on the properties of chitosan modified by the tannic acid addition was studied. Tannic acid was added to chitosan solution in different weight ratios and after solvent evaporation thin films were formed. The properties of the films such as thermal stability, Young modulus, ultimate tensile strength, moisture content, swelling behavior before and after UV-irradiation were measured and compared. Moreover, the surface properties were studied by contact angle measurements and by the use of atomic force microscopy. The results showed that UV-irradiation caused both, the degradation of the specimen and its cross-linking. The surface of the films made of chitosan modified by the addition of tannic acid was altered by UV-irradiation.

Mechanical and Morphological Studies of Chitosan/Clay Composites

In the present paper, the results of mechanical properties and atomic force microscopy studies of chitosan (Ch) with montmorillonite (MMT) or nano-clay are presented. The blends composed of chitosan (Ch) with montmorillonite (MMT) have been prepared as material designed for cosmetic industries and/or biomedical applications. Mechanical properties such as the ultimate tensile strength, percentage elongation and Youngs modulus of films have been determined and compared. Addition of nanoclay after surface modification improved the mechanical properties more than montmorillonite without modification. The surface properties of the chitosan and montmorillonite films and their composites have been studied by tapping-mode atomic force microscopy (AFM). The changes of topography images were considered by determining the root mean square (Rms) deviation in the image data. AFM images show differences in surface properties of chitosan films, chitosan/MMT films, and chitosan/nanoclay films. Surface roughness decreased with addition of MMT and/or nanoclay into chitosan matrix. The obtained results suggest that the properties of chitosan and montmorillonite composites depend on the blend composition and on the way of surface modification of nano-clay.

Preparation and characterization of composites based on the blends of collagen, chitosan and hyaluronic acid with nano-hydroxyapatite

3D porous composites based on the blend of chitosan, collagen and hyaluronic acid with the addition of nano-hydroxyapatite were prepared. SEM images for the composites were made and the structure was assessed. Mechanical properties were studied using a Zwick&Roell Testing Mashine. In addition, the porosity and density of composites were measured. The concentration of calcium ions released from the material was detected by the complexometric titration method. The results showed that in 3D porous sponge based on the blend of chitosan, collagen and hyaluronic acid, inorganic particles of nanohydroxyapatite can be incorporated, as well as that the properties of 3D composites depend on the material composition. Mechanical parameters and thermal stability of ternary biopolymeric blends were improved by the addition of hydroxyapatite. Moreover, the porosity of ternary materials was higher than in materials based on pure chitosan or collagen. All composites were characterized by a porous structure with interconnected pores. Calcium ions can be released from the composite during its degradation in water.

Modification of 3D materials based on chitosan and collagen blends by sodium alginate

ABSTRACT The aim of this work was to study the properties of chitosan/collagen blend modified by sodium alginate. 3D composites of chitosan/collagen blend were prepared by freeze drying technique. The results showed that sodium alginate modified the properties of the 3D composite of chitosan/collagen blends. The porosity decreased and the mechanical properties were improved. Mechanical parameters increased with an increasing amount of sodium alginate in chitosan/collagen composite. Materials after cross-linking by sodium alginate can be used in medical applications to produce implants or wound dressings.

Surface and thermal properties of collagen/hyaluronic acid blends containing chitosan

The structure and surface properties of binary and ternary blends containing collagen (Coll), hyaluronic acid (HA) and chitosan (Ch) were investigated by contact angle measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Thin films of Coll/HA and Coll/HA/Ch blends have been formed by casting methods from aqueous acid solutions. The surface roughness, hydrophobic/hydrophilic character and thermal stability of Coll/HA were changed after addition of chitosan. Thermal stability of binary blends increase upon the addition of chitosan. The results of contact angle and the surface free energy revealed that hyaluronic acid films are more polar than collagen and chitosan films. The surface energy and its polar and dispersive components of binary and ternary blends were calculated and more hydrophilic films were produced by the addition of HA and chitosan, also resulting in more thermally stabile materials. These results demonstrate that collagen interacts with hyaluronic acid and chitosan changing the surface properties of polymer films.

Biological Properties of Chitosan/Collagen Composites

The properties of new materials based on the blends of collagen and chitosan were studied along with their biological compatibility. Mechanical properties, thermal analysis, FTIR spectra and SEM images were obtained for different blends of chitosan/collagen in weight ratios 75/25, 50/50, 25/75. The materials in the form of 2D sheets were then subjected to cultures of human mesenchymal stem cells (hMSC) directed toward osteogenesis with ascorbate-2-phosphate and dexamethasone. The results showed that specified amounts of components influence the mechanical properties of obtained materials. Proliferation of hMSC decreased with increasing amounts of chitosan in collagen/chitosan films. However, the cellular activity of alkaline phosphatase (ALP), a marker of preosteoblasts and active osteoblasts, for plain collagen films ALP was the highest, whereas different ratios of collagen in chitosan/collagen composites had no effect on overall good ALP activity of hMSC. Based on the presented data, we believe the obtained materials are suitable for bone tissue engineering strategies.

New composite materials prepared by calcium phosphate precipitation in chitosan/collagen/hyaluronic acid sponge cross-linked by EDC/NHS

Nowadays, fabrication of composite materials based on biopolymers is a rising field due to potential for bone repair and tissue engineering application. Blending of different biopolymers and incorporation of inorganic particles in the blend can lead to new materials with improved physicochemical properties and biocompatibility. In this work 3D porous structures called scaffolds based on chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Scaffolds were cross-linked by EDC/NHS. Infrared spectra for the materials were made, the percentage of swelling, scaffolds porosity and density, mechanical parameters, thermal stability were studied. Moreover, the scaffolds were used as matrixes for the calcium phosphate in situ precipitation. SEM images were taken and EDX analysis was carried out for calcium and phosphorous content determination in the scaffold. In addition, the adhesion and proliferation of human osteosarcoma SaOS-2 cells was examined on obtained scaffolds. The results showed that the properties of 3D composites cross-linked by EDC/NHS were altered after the addition of 1, 2 and 5% hyaluronic acid. Mechanical parameters, thermal stability and porosity of scaffolds were improved. Moreover, calcium and phosphorous were found in each kind of scaffold. SEM images showed that the precipitation was homogeneously carried in the whole volume of samples. Attachment of SaOS-2 cells to all modified materials was better compared to unmodified control and proliferation of these cells was markedly increased on scaffolds with precipitated calcium phosphate. Obtained materials can provide the support useful in tissue engineering and regenerative medicine.

Physico-chemical properties of three-component mixtures based on chitosan, hyaluronic acid and collagen

ABSTRACT The aim of this work was preparation of biopolymer materials based on blends of chitosan, hyaluronic acid and collagen. The properties of blend films have been investigated by contact angle measurements and atomic force microscopy. The contact angle measurements showed that chitosan films are more polar after addition of hyaluronic acid and collagen. The AFM results showed that the addition of chitosan to hyaluronic acid led to the increase of surface roughness. Moreover, miscibility studies of biopolymeric blends were also done using the viscometric method. Viscometric studies indicated that two-component and three-component blends are partially miscible.