Layer-by-Layer Film Growth Using Polysaccharides and
Recombinant Polypeptides: A Combinatorial Approach
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Abstract
Nanostructured films consisting of
polysaccharides and elastin-like
recombinamers (ELRs) are fabricated in a layer-by-layer manner. A
quartz-crystal microbalance with dissipation monitoring (QCM-D) is
used to follow the buildup of hybrid films containing one polysaccharide
(chitosan or alginate) and one of several ELRs that differ in terms
of amino acid content, length, and biofunctionality <i>in situ</i> at pH 4.0 and pH 5.5. The charge density of the ingredients at each
pH is determined by measuring their ζ-potential, and the thickness
of a total of 36 different films containing five bilayers is estimated
using the Voigt-based viscoelastic model. A comparison of the values
obtained reveals that thicker films can be obtained when working at
a pH close to the acidity constant of the polysaccharide used (near-p<i>K</i><sub>a</sub> conditions), suggesting that the construction
of such films is more favorable when based on the presence of hydrophobic
interactions between ELRs and partially neutralized polysaccharides.
Further analysis shows that the molecular weight of the ELRs plays
only a minor role in defining the growth tendency. When taken together,
these results point to the most favorable conditions for constructing
nanostructured films from natural and distinct recombinant polypeptides
that can be tuned to exhibit specialized biofunctionality for tissue-engineering,
drug-delivery, and biotechnological applications