ABSTRACT

Injectable collagen is a concentrated dispersion of phase-separated collagen fibers in aqueous solution. The structure and properties of collagen fibers are defined by the magnitudes of electrostatic and hydrophobic attractive forces between neighboring collagen molecules within collagen fibers. The structure and mechanical properties of collagen fiber dispersions were studied by dynamic rheological measurements and by polarized microscopy (32). Rheological measurements were performed therein over pHs ranging from 6 to 9 and over temperatures ranging from 283 to 298 K. At higher pHs, the fiber dispersions possessed more rigid fibers and stronger interfiber attractive forces. This response is argued to result from changes in the ionization of amino acid side chains, which result in larger net electrostatic attractive forces. Raising the temperature caused fibers to become rigid through enhanced hydrophobic attractive forces. Gels formed by 10wer-pH-highertemperature fiber dispersions possess different properties than gels formed at higher pHs and lower temperatures.