Material Technology

Altering associations in aqueous solutions of a hydrophobically modified alginate in the presence of beta-cyclodextrin monomers

Galant, C. , Kjøniksen, A.-L. , Nguyen, G.T.M. , Knudsen, K.D. , Nyström, B.
Journal of physical chemistry B, Vol. 110 (2006), no. 1, 190-195
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The formation of associative networks in semidilute aqueous solutions of hydrophobically modified alginate (HM-alginate) is dependent on intermolecular hydrophobic interactions. Addition of β-cyclodextrin (β-CD) monomers to the system provides decoupling of these associations via inclusion complex formation with the polymer hydrophobic tails. This results in a dramatic decrease in the viscoelastic response of the system and a more extended local structure of the polymer chains, as shown by small-angle neutron scattering (SANS) measurements. The zero-shear viscosity decreases about an order of magnitude when the β-CD concentration is increased from 0 to 12 mm. The lifetime of the associative network decreases strongly with increasing levels of β-CD addition. These findings clearly demonstrate that the hydrophobic association effect is efficiently reduced as the amount of β-CD is increased. In the framework of drug delivery, this effect may be useful to improve the release of therapeutic molecules that can be entrapped in the polymer matrix. © 2006 American Chemical Society.
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