Specific Interactions in Model Charged Polysaccharide Systems

Abstract

Temporary networks were obtained from mixtures of two derivatized chitosans, one with -cyclodextrin (CD) cavities and the other with adamantyl (AD) moieties, randomly distributed along the chains. The viscoelastic response of these original systems in which cyclodextrin-adamantane complexes play a role of interchain junctions (sticky points) was investigated as a function of polymer concentration, degree of modification, ionic strength, temperature, and addition of competitive molecules. In the semidilute regime, an increase of the long relaxation times with the density of CD-AD complexes is observed, reflecting the hindrance of local flow processes due to reversible interchain bonds. The strong dependence of the apparent relaxation energy appears as a consequence of the temperature dependence of CD-AD interaction. However, contrary to the long time dynamics, the elastic plateau modulus of the transient network at short times does not seem to be much influenced by the density of stickers. The value of the plateau modulus is mainly dependent on polymer concentration.

Supramolecular Guest–Host Interactions for the Preparation of Biomedical Materials

“…While low modification resulted in weak supramolecular networks (typical G' < 100Pa), their results demonstrated the importance of polymer concentration, charge, and competitive binding on network assembly. 62 Moreover, theoretical and experimental approaches have been combined to illustrate the importance of multivalent and inter-polymer interaction to generate high avidity and network stability. [63][64] Toward harnessing this understanding, our group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 has demonstrated that higher degrees of modification of HA with these same guest-host groups enables formation of more robust supramolecular hydrogels (G' = 10 kPa possible) through generation of larger net avidity between polymers which may be enhanced by multifold polymer junctions.…”

Protein‐Release Behavior of Self‐Assembled PEG–β‐Cyclodextrin/PEG–Cholesterol Hydrogels

“…[38] Driven by hydrophobic and van der Waals interactions, the relatively hydrophobic pocket of bCD serves as a reversible binding site for a wide range of lipophilic molecules (e.g., adamantane and cholesterol). [39][40][41] Reversible hydrogel systems, for example, those composed of adamantane-and bCD-grafted chitosan [42] or hyaluronic acid [33,43] have been described in the literature. Also, stimuli-responsive gels were formed after combining poly(acrylamide) derivatized with either bCD or aromatic guest molecules.…”

Spontaneous association of hydrophobized dextran and poly-β-cyclodextrin into nanoassemblies.

“…Huh and co-workers described systems, in which CDs formed inclusion complexes with poly(ethylene oxide)-grafted polysaccharides [30,31]. More recently, supramolecular gel-like networks were obtained by mixing a CD-bearing host polymer and a hydrophobically modified guest polymer [32][33][34][35][36]. Using the same approach, studies were carried out in our laboratory to design a stable dispersion of 200 nm in size nanoassemblies, combining the properties of both polysaccharides and CDs [37].…”