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Updated: May 25, 2026

Thermal Scanning Conductometry (TSC) as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels
Published on: January 23, 2018
In situ gelling properties of anionic thiomers
Fabian Hintzen1, Flavia Laffleur, Duangkamon Sakloetsakun
1Department of Pharmaceutical Technology, Institute of Pharmacy, Leopold-Franzens-University Innsbruck, Josef-Möller-Haus, Innrain 52, Innsbruck, Austria/Europe.
Abstract:
The aim of this study was to investigate in situ crosslinking systems of anionic thiolated polymers. In order to accelerate the increase in dynamic viscosity of thiolated polymers (thiomers), they were combined with hydrogen peroxide, carbamide peroxide and ammonium persulfate. Thiomers (pectin-cysteine (Pec-Cys), sodium carboxymethylcellulose-cysteine (NaCMC-Cys) and poly(acrylic acid)-cysteine (PAA-Cys)) were synthesized via amide bond formation between the carboxylic acid group of polymers and the primary amino group of l-cysteine. The rheological properties of 1% (m/v) thiomer solutions with oxidizing agents were compared by oscillatory measurements over time (120 min). Pec-Cys and NaCMC-Cys with hydrogen and carbamide peroxide showed a sol-gel phase transition within a few minutes and scored up to 13,000-fold increase in dynamic viscosity. Furthermore, only thiomers exhibiting a polysaccharide backbone (Pec-Cys and NaCMC-Cys) showed a significant increase in viscosity (p < 0.05). In contrast, measurements of carbohydrate thiomers in combination with ammonium persulfate showed an initial increase in viscosity. Afterwards, a decrease in viscosity was observed likely caused by chain scission. According to these results, carbohydrate thiomer/oxidizing agent systems might be useful for various pharmaceutical applications such as for in situ gelling liquid/semisolid formulations or in tissue engineering.
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