This work reports the effects of rhamsan, a bacterial polysaccharide, over anionic collagen gels. Collagen: rhamsan interaction occurred independently from pH even at extremely low collagen:rhamsan ratios and materials were characterized in the solid state by an increase in thermal stability with an increase in polysaccharide concentration. No disruption of the triple helix secondary structure of tropocollagen was observed. The most striking effect of rhamsan addition over anionic collagen gels was the high increase in viscosity. A dependence study on pH and temperature suggests that electrostatic or hydrophobic forces are probably not involved in the process. Anionic collagen and anionic collagen: rhamsan gel micrographs at neutral pH showed the presence of spherical vesicles, different from the expected fibrillar pattern of native collagen. A model based on the action of rhamsan over structured water associated to collagen assembly in solution is proposed. Most important, anionic collagen:rhamsan gels showed a thermal stability compatible for its use as an injectable collagen biomaterial, thus avoiding the use o glutaraldehyde as an stabilizing agent.
Anionic collagen; rhamsan; gels; biomaterials; characterization
