Marilia M. Horn

Influence of collagen addition on the thermal and morphological properties of chitosan/xanthan hydrogels

This study investigates the collagen influence on thermal and morphological characteristics of chitosan/xanthan hydrogels for potential tissue engineering applications. Anionic collagen was prepared by selective hydrolysis of type I collagen found in bovine tendons. Chitosan was obtained from the partial deacetylation of squid pen β-chitin and xanthan was acquired from Fluka. The hydrogels were obtained in different ratios and were characterized by thermal and morphological analysis. FT-IR suggested only electrostatic interactions between NH3(+) groups of chitosan and COO(-) groups of xanthan and collagen. Thermogravimetric curves showed that hydrogels contain a great amount of water (above 98%) and the presence of collagen does not change this characteristic. Freezing-bound water transition in DSC curves was shifted to higher values due to the increase of water/polymer interaction, mainly when different ratios of chitosan and xanthan were used. SEM images showed sheet-form structures with the presence of collagen promoting an increase in pore size.

Determinação da energia de ativação em hidrogéis poliméricos a partir de dados termogravimétricos

Polyelectrolyte hydrogels formed by chitosan/xanthan (QX) and chitosan/xanthan/collagen (QXC) were prepared and thermogravimetric curves at different heating rates were obtained, with the aim of determining kinetic parameters using the Flynn-Wall method. The calculated activation energy was 3.44 kJ.mol-1 (QX ) and 14.84 kJ.mol-1 (QXC), suggesting stronger interactions in QXC hydrogel structure than in the QX hydrogel, probably due to the presence of carboxyl groups of collagen molecules.

Rheological characterization of chitosan/starch blends by varying polyols and amylopectin content

Abstract This manuscript reports on the rheological characterization of chitosan/starch blends with variations in the amylopectin contents and polyols as plasticizers agent. All prepared blends were homogeneous as evidenced by scanning electron microscopy results. The G′ and G″ moduli as a function of frequency showed the predominance of non-elastic and a weak-gel behavior. The Power Law model fitted the flow curves indicated the influence of the amylose content and polyol presence in K values. The flow behavior index (n) of chitosan/starch blends decreased as function of amylose content and reduces the non-Newtonian behavior of blends. The temperature dependence of G′ and G″ moduli showed the crossover of the moduli with the temperature enhance. For both starches blended with chitosan, the addition of plasticizer promoted a rise in the gelation temperature as polyol produces a higher number of hydrogen-bonding interactions. FTIR results for blends containing polyols showed the absence of chemical interactions between the components. Graphical Abstract