Supramolecular Reinforcement of Polymer-Nanoparticle Hydrogels for Modular Materials Design

Moldable hydrogels are increasingly used as injectable or extrudable materials in biomedical and industrial applications owing to their ability to flow under applied stress (shear-thin) and reform a stable network (self-heal). Nanoscale components can be added to dynamic polymer networks to modify their mechanical properties and broaden the scope of applications. Viscoelastic polymer-nanoparticle (PNP) hydrogels comprise a versatile and tunable class of dynamic nanocomposite materials that form via reversible interactions between polymer chains and nanoparticles. However, PNP hydrogel formation is restricted to specific interactions between select polymers and nanoparticles, resulting in a limited range of mechanical properties and constraining their utility. Here, a facile strategy to reinforce PNP hydrogels through the simple addition of alpha-cyclodextrin (alpha CD) to the formulation is introduced. The formation of polypseudorotoxanes between alpha CD and the hydrogel components resulted in a drastic enhancement of the mechanical properties. Furthermore, supramolecular reinforcement of CD-PNP hydrogels enabled decoupling of the mechanical properties and material functionality. This allows for modular exchange of structural components from a library of functional polymers and nanoparticles. alpha CD supramolecular binding motifs are leveraged to form CD-PNP hydrogels with biopolymers for high-fidelity 3D (bio)printing and drug delivery as well as with inorganic NPs to engineer magnetic or conductive materials.

Automated summary

Moldable hydrogels are versatile materials used in biomedical and industrial applications. This study introduces a simple strategy to reinforce polymer-nanoparticle (PNP) hydrogels by adding alpha-cyclodextrin (alpha CD), resulting in enhanced mechanical properties. The supramolecular reinforcement of CD-PNP hydrogels allows for modular exchange of structural components and enables a wide range of applications.