Unexplored capabilities of chemiluminescence and thermoanalytical methods in characterization of intact and degraded hyaluronans J. Rychly ´ a, * , L. S ˇ olte ´s b , M. Stankovska ´ b , I. Janigova ´ a , K. Csomorova ´ a , V. Sasinkova ´ c , G. Kogan c , P. Gemeiner c a Polymer Institute, CEDEBIPO, Centre of Excellence for Degradation of Biopolymers, Slovak Academy of Sciences, SK-84236 Bratislava, Slovak Republic b Institute of Experimental Pharmacology, Slovak Academy of Sciences, SK-84104 Bratislava, Slovak Republic c Institute of Chemistry, Slovak Academy of Sciences, SK-84538 Bratislava, Slovak Republic Received 22 May 2006; accepted 13 July 2006 Available online 11 September 2006 Abstract Three intact and four degraded hyaluronans were investigated by using chemiluminometry, differential scanning calorimetry, and thermog- ravimetry. Degradation of hyaluronan was induced by a system containing H 2 O 2 alone (882 mM); 55 mM H 2 O 2 plus 1.25 mM CuCl 2 ; NaOCl alone (10 mM); and NaOCl plus CuCl 2 and ascorbic acid (10 mM, 0.1 mM, and 100 mM, respectively). The four different oxidative systems yielded biopolymer fragments represented by similar viscosity characteristics. The results obtained by using chemiluminescence and thermoa- nalytical methods indicate that hyaluronans of similar rheological properties could be distinguished from each other. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Hyaluronan; Hyaluronan degradation; Chemiluminometry; Differential scanning calorimetry; Thermogravimetry; IR spectroscopy 1. Introduction Hyaluronan (HA) is a linear glycosaminoglycan built of di- saccharide repeating units comprising D-glucuronate linked through b-(1 / 3) glycosidic linkage to N-acetyl-D-glucos- amine. These disaccharide structural units are linked via b- (1 / 4) glycosidic bonds. Hyaluronan is an essential functional component of almost all tissues in the vertebrate organism. Various animal tissues e e.g. rooster combs, shark skin, bovine eyeballs e have been used as sources of isolation and production of high molar mass HAs. Since in biological materials hyaluronan is present in a complex system, linked and/or mixed with other biopoly- mers, several separation procedures have to be applied to iso- late a pure compound [1,2]. The mean molar mass of the commercially available ‘‘extractive’’ HA preparations ob- tained from animal tissues is mostly in the range from several hundred thousands g/mol up to approximately 2500 kg/mol. To date, the demand for HA-based materials approved for ap- plications in human medicine is being satisfied by high molar mass HAs prepared from rooster combs. For example, Hea- lon Ò (Pharmacia & Upjohn, Inc., Peapack, NJ, U.S.A.) e used in viscosurgery at eye implant insertion e has a mean molar mass of about 2500 kg/mol. Although animal tissues, primarily rooster combs, were in- volved at the early stages of production of the clinically utiliz- able materials approved by FDA, e.g. in eye surgery O O CO 2 OH OH O O CH 2 OH HO NH C O CH 3 D-glucuronate N-acetyl-D-glucosamine * Corresponding author. Tel.: þ421 9 0270 4917; fax: þ421 2 5477 5923. E-mail address: jozef.rychly@savba.sk (J. Rychly ´). 0141-3910/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2006.07.009 Polymer Degradation and Stability 91 (2006) 3174e3184 www.elsevier.com/locate/polydegstab