Biodegradable bioartificial materials made with chitosan and poly(vinyl alcohol). Part I: Physicochemical characterization.

Polymers have widespread applications in therapeutics, and their use can play important structural and functional roles in different disease conditions. Bioartificial biodegradable materials, to be used as biomaterials and, in particular, as localized drug carriers, were prepared mixing chitosan (CHI) and poly(vinyl alcohol) (PVA), then manufactured as films, and finally cross-linked with glutaraldehyde (GTA), both in the absence and in the presence of the edible plasticizer sorbitol (SOR). The materials were characterized by Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), ther-mogravimetric analysis (TGA), X-ray diffraction, scanning electron microscopy (SEM), and tensile test. The FTIR spectroscopy and the X-ray diffraction indicated that the presence of CHI lowers the crystallinity of PVA, and that the cross-linking with GTA does not modify the interactions between the two polymers, but only forms bridges between the different chains. In addition, the thermodynamic parameters for PVA, evaluated from the DSC measurements, confirmed that the PVA structure was less crystalline in the blends than in the pure state. The addition of SOR as a plasticizer to the CHI/PVA blends generally improved the characteristics of the films, making the cross-linked films less brittle, as confirmed by the SEM measurements and by the mechanical test. The TGA measurements confirmed the presence of chemical interactions between the polymers, as indicated by the DSC measurements. On the whole, the physicochemical properties of the blends showed the strong interactions existing between the component materials.