In this work, low molecular weight (17 kDa) hyaluronan was modified by dodecanoyl substituents. The activation of dodecanoic acid was mediated by benzoyl chloride towards the preparation of a mixed anhydride, which reacts in a second step with HA in water mixed with an organic solvent. The effect of the cosolvent was studied and showed an even distribution of substituents and higher reaction rate in water: 1,4-dioxane compared to water:tert-butanol where substituents occupy adjacent positions. The chemical characterization of the prepared derivatives was elucidated by NMR, FTIR spectroscopy, thermal analyses, and gas chromatography, while the distribution of substituents was evaluated by enzymatic degradation. Molecular-dynamics simulations reveal opposite solvent separations around HA and dodecanoyl chains, that is stronger in water:tert-butanol solution. The resulting incompatibility of solvation-shells of the two entities repels the reaction intermediates from the HA chain and drives them towards the already bound substituents, explaining the observed differences in the distribution evenness. Thus, the influence of the solvent on the reaction selectivity is observed by shielding reactive sites around HA. Therefore, a control of the distribution of the substituents was obtained by defining the concentration of HA and used cosolvent.
This work concerns the chemical modification of medium molecular weight hyaluronan for ophthalmic applications. The synthesis of amphiphilic HA with dodecanoyl moities was carried out under mild aqueous conditions. Perfect control of the degree of substitution was obtained by varying the molar ratio of activated fatty acid used in the reaction feed. Moreover, the preparation of the derivatives was optimized to achieve the desired degree of substitution (DS = 9.0 ± 0.2 %). The prepared hyaluronan derivatives were water-soluble and exhibited self-associating properties (amphiphilicity). The structure of the prepared derivatives was elucidated by NMR spectroscopy, rheology, turbidity, SEC-MALLS, and gas chromatography (GC). The hydrophobic moieties increase the solution viscosity by physical crosslinking. Low concentration of HAC12 is needed to prepare highly viscous solutions with potential use for ophthalmic applications. Amphiphilic HA kept the biocompatibility of hyaluronan. The degree of substitution and Mw of the amphiphilic HA controls the sterilization by filtration. The protection against desiccation was tested using human keratinocytes (HaCaT) cells lines.
- MeSH
- buněčné linie keratinocytů HaCaT MeSH
- buňky NIH 3T3 MeSH
- hydrofobní a hydrofilní interakce MeSH
- kyselina hyaluronová chemie MeSH
- kyseliny laurové chemie MeSH
- lidé MeSH
- molekulová hmotnost MeSH
- muciny chemie MeSH
- myši MeSH
- povrchové napětí účinky léků MeSH
- příprava léků metody MeSH
- reologie metody MeSH
- syndromy suchého oka farmakoterapie MeSH
- viabilita buněk účinky léků MeSH
- viskozita účinky léků MeSH
- zvířata MeSH
- zvlhčující oční kapky chemie farmakologie terapeutické užití MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
