Rheological behavior of anionic collagen injectable gels in the presence of rhamsan for plastic surgery applications.

The present paper describes the rheological properties of anionic collagen gels and anionic collagen:rhamsan composites gels in the concentration of 0.7, 4 and 6%, estimated to be used as injectable biomaterials for plastic reconstruction. Rheological studies of these gels showed that independently of pH, composition and concentration the viscoelastic behavior was dependent on the frequency, with the storage modulus always greater than the loss modulus (G' > G'' and delta < 45 degrees ). Creep experiments showed that anionic collagen:rhamsan composites equilibrated at pH 7.4 were less elastic and more susceptible to deformation in comparison to gels equilibrated at pH 3.5. Flow experiments indicated that the force needed for the extrusion of anionic collagen:rhamsan composites, in comparison to anionic collagen, was significantly smaller and with a smoother flow, suggesting the association with rhamsan may be a good alternative in the replacement of glutaraldehyde to stabilize the microfibril assembly of commercial collagen gel preparations. Finally, on the basis of dynamic viscosity profiles found for different preparations, some of these composites are potential candidates to be utilized in laryngology.