Viscoelastic and mechanical properties of hyaluronan films and hydrogels modified by carbodiimide

•Modified hyaluronan in two geometrical forms was prepared.•Modified hyaluronan films can be stretched up to 130% before breaking.•Elasticity of hyaluronan gels depend on their geometrical form.•Cylindrical form of modified hyaluronan gels improve their creep recovery ability.

This study investigated an effect of different ways of the preparation of insoluble hyaluronan material on its mechanical and viscoelastic properties. Hyaluronan (NaHy) of molecular weight Mw = 500,000 g mol−1 was modified with N-(3-dimethylaminopropyl-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), to be able absorb liquid without changing its mechanical properties. The modified, water insoluble NaHy materials were prepared in different geometry; as modified films and modified cylinders with exact dimensions. The occurrence of modification was confirmed by FT-IR (Fourier transform infrared spectroscopy) and 1H NMR (proton nuclear magnetic resonance) spectroscopy and swelling test. The determined mechanical and viscoelastic properties of unmodified and modified hyaluronan revealed the high dependency of elasticity changes depending on the gel processing method. Moreover, NaHy gels in the cylindrical form with the sponge-like structure predominant them as a convenient geometry for application in a humid environment.

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