Chemico-physical properties of hyaluronan-based sponges.

The aim of this study was to obtain information on the chemico-physical and surface properties of the hyaluronan total benzylic ester sponges to evaluate their stability, surface "cleanliness" and handling for the applications in the tissue engineering. The thermal analysis, the characterization of surface chemical composition and the swelling test were performed on these materials. Moreover, the morphological changes, the rheological behavior, and the molecular weight loss in function of the time were monitored when the sponges were incubated in cell culture medium. The results showed that the sponges were thermally stable up to 220 degrees C and the surface composition was different from that of the bulk for C-O contribution. No contaminants were detected. In culture medium, the samples swelled assuming the rheological properties of biopolymer gel. When the sponges were in contact with the culture medium, their molecular weight remained stable for the first day and a loss of 11% and 31% was recorded for samples removed from culture medium after 3 and 7 days, respectively. With the scanning electron microscopy analysis, the spongy structure appeared with open interconnecting pores. The micrographs related to the samples after incubation in culture medium showed that the degradation was evident on the surface after 1 day. The deterioration of the pore walls and the presence of craters increased with time and, after 3 days, the phenomena were present also in the section.