Macromolecular structure and film properties of enzymatically-engineered high molar mass dextrans

• Published in: Carbohydrate polymers 2018-02, Vol.181, p.337-344
• Main Authors: Faucard, Pauline, Grimaud, Florent, Lourdin, Denis, Maigret, Jean-Eudes, Moulis, Claire, Remaud-Siméon, Magali, Putaux, Jean-Luc, Potocki-Véronèse, Gabrielle, Rolland-Sabaté, Agnès
• Format: Article
• Language: English
• Subjects: Asymmetrical flow field-flow fractionation; Chemical Sciences; Dextrans; Hygromechanical properties; Polymers; Sucrose-active enzymes; Thermal properties
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.10.065

[Display omitted] •Dextransucrases and branching enzymes were combined to produce new dextrans.•High molar mass dextrans with controlled architecture were obtained.•AF4-MALLS allowed characterizing and differentiating each dextran.•These dextrans present a good film-forming ability.•The mechanical properties of dextran films depend on their structure. New α(1→2) or α(1→3) branched dextrans with high molar masses and controlled architecture were synthesized using a dextransucrase and branching sucrases. Their molecular structure, solubility, conformation, film-forming ability, as well as their thermal and mechanical properties were determined. These new dextrans present structures with low densities from 9,500 to 14,000gm−3 in H2O/DMSO medium, their molar mass, size and dispersity increase with increasing branching degree (weight-average molar mass up to 109gmol−1 and radius of gyration around 500nm). Dextrans exhibit a glass transition between 40.5 and 63.2°C for water content varying from 12.2 to 14.1%. The effect of branching is mainly observed on the ability of dextran to crystallize. They have a good film-forming ability with a storage modulus which varies from 2 to 4GPa within a relative humidity range of 10–50%.