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Preparation and Characterization of a Hydrogel from Low-Molecular Weight Hyaluronic Acid

P. A. Netti

Department of Materials and Production Engineering, University of Naples, ‘‘Federico II’’, P.le Tecchio 80 – 80125 Naples, Italy

L. Ambrosio

L. Nicolais

Institute of Composite and Biomedical Materials, National Research Council, P.le Tecchio 80 – 80125 Naples, Italy

A. Sannino

Department of Innovation Engineering, University of Lecce, via Monteroni – 73100 Lecce, Italy

A relatively low-molecular weight sample of hyaluronic acid (HA) was chemically modified by means of a cross-linking reaction with water-soluble carbodiimide and L-lysine methyl ester to form a chemical hydrogel. FT-IR analysis performed on the precursors and on the cross-linked hydrogel indicated the formation of ester bonds between different HA molecules that led to an intermolecular cross-linking. Hydrogel swelling kinetics as well as equilibrium sorption properties were evaluated. A swelling ratio of 250 was observed after immersion in distilled water for 7 h. Rheological measurements by means of a plate–plate rheometer of the cross-linked sample showed non-Newtonian and pseudoplastic behavior, while the uncross-linked HA showed Newtonian behavior and a viscous characteristic. Morphological analysis of these microstructures by scanning electron microscopy indicated that the freeze-dried crosslinked hydrogel presents a more closed-pore structure and higher density of pores than the freeze-dried original HA.

Key Words: hydrogel • cross-linking • carbodiimide • FT-IR • SEM • swelling • rheological properties

Journal of Bioactive and Compatible Polymers, Vol. 19, No. 1, 5-15 (2004)
DOI: 10.1177/0883911504041608


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