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Depolymerization study of sodium hyaluronate by flow field-flow fractionation/multiangle light scattering.
Ji Hye Kwon1, Euijin Hwang, Il-Hwan Cho
1Department of Chemistry, Yonsei University, Seoul, 120-749, South Korea.
Analytical and Bioanalytical Chemistry
|August 4, 2009
Summary
Thermal treatment breaks down ultrahigh-molecular-weight sodium hyaluronate (NaHA) into smaller molecules. This process involves unfolding compact structures and suggests that very high molecular weights result from molecular aggregation rather than single long chains.
Area of Science:
- Polymer Chemistry
- Materials Science
- Biochemistry
Background:
- Ultrahigh-molecular-weight sodium hyaluronate (UHMW NaHA) is a complex biopolymer with significant applications.
- Understanding the thermal degradation behavior of UHMW NaHA is crucial for its processing and application stability.
- Previous studies have not fully elucidated the structural origins of UHMW NaHA's high molecular weight.
Purpose of the Study:
- To systematically investigate the thermal depolymerization of UHMW NaHA.
- To determine the structural changes and molecular weight alterations during thermal degradation.
- To differentiate between chain scission and dissociation of aggregated structures as mechanisms for MW reduction.
Main Methods:
- Utilized frit-inlet asymmetrical flow field-flow fractionation (FI-AFlFFF) for size separation of NaHA samples.
- Coupled FI-AFlFFF with multiangle light scattering (MALS) and differential refractive index (DRI) detection.
- Isolated specific molecular weight fractions of NaHA for targeted thermal treatment and analysis.
Main Results:
- Observed time-dependent depolymerization of UHMW NaHA into lower molecular weight components upon thermal treatment.
- Documented unfolding of compact structures within the UHMW NaHA samples.
- Analysis of fractionated samples indicated that the ultrahigh molecular weight region (>10^7 Da) likely arises from the aggregation of large NaHA molecules, not solely from long individual chains.
Conclusions:
- Thermal treatment induces depolymerization and structural unfolding in UHMW NaHA.
- The exceptionally high molecular weights observed in UHMW NaHA are predominantly attributed to the formation of supermolecular structures through aggregation.
- FI-AFlFFF/MALS/DRI is an effective technique for characterizing the thermal degradation and structural behavior of polymers like NaHA.
