Hierarchical stabilization of bioactive hydrogels by multi-arm peptide-polymer supramolecular staples

Supramolecular peptide hydrogels offer attractive bioactivity and dynamic mechanical behavior for three-dimensional cell culture and tissue engineering. However, their broader use is often limited by slow gelation and insufficient mechanical stability. Here, we introduce a molecular design strategy in which a tryptophan zipper pendant multiarm poly (ethylene glycol) (Trpzip-PEG) conjugate is incorporated into Trpzip nanofibrillar hydrogels to facilitate hierarchical tuning of materials properties. Trpzip peptides self-assemble into entangled nanofiber networks, while the addition of Trpzip-PEG conjugate induces reorganization of these assemblies. Electron microscopy and neutron scattering reveal more densely bundled fibers with increased microporosity and a fractal network architecture, suggesting that the conjugate acts as a supramolecular binder or "staple" coordinating nano- and micro-scale organization. These structural changes markedly accelerate gelation and increase stiffness, yield behavior, and thixotropic recovery. Importantly, the Trpzip/Trpzip-PEG supramolecular hybrid hydrogels remain cytocompatible, supporting adipose-derived stem cell adhesion, viability, and proliferation over time. Together, these findings demonstrate that Trpzip/Trpzip-PEG hybrid hydrogels offer a versatile platform for engineering mechanically robust yet bioactive soft materials for 3D cell culture, biofabrication, and regenerative medicine applications.