LAUSR

Chitosan is a pH-responsive self-assembling polysaccharide that can be electrodeposited to form a hydrogel film. During electrodeposition a host of dynamic processes occur simultaneously over a hierarchy of length scales. Experiments have shown that the microstructure and properties of the deposited gels are highly dependent on the solution conditions and imposed electrical signals. However, detailed mechanisms are not understood. Here we use molecular dynamics simulations to explore the conformational dynamics of individual chitosan chains composed of 20 glucosamine units in aqueous solution. Simulations yield a total persistence length of about 5 nm, in agreement with the lower range of the experimental estimates and supporting a worm-like-chain model. The surprisingly high flexibility arises from the glycosidic linkage sampling an appreciable population of anti-ψ conformation which is associated with backbone bending and higher flexibility. Significantly, the presence of added salt increases the anti-ψ...