Peptide-based networks are promising materials for hydrogel systems due to their biocompatibility, ability to form complex architectures, and stimuli-responsive behavior. Physical gels made from these materials are of particular interest, as non-covalent crosslinks provide the opportunity for networks to reform after being broken by forces, such as shear or compression. These reversible bonds are necessary for applications such as injectable hydrogels. In these systems, the network yields under shear forces during injection, and recovers its original strength once in place. However, it often is challenging to balance the desire for dynamic bonds with the need for robust mechanical properties. Hybrid peptide-polyurea (PU) materials may provide a platform for physical gels with tunable mechanics. In this work, linear, non-chain extended PU gels synthesized from Lys-PEG-Lys triblock precursors are studied. Poly(ε-carbobenzyloxy-L-lysine) (PZLY) segments allow for gel formation via assembly of secondary structures as well as hydrogen bonding interactions with the PEG block. Tunability of gel properties is achieved though variations in peptide content and peptide repeat length, which have been shown to influence secondary structure in the solid-state. Hybrid polyureas with higher levels of beta sheet formation are expected to result in stiffer gels than alpha helix dominated networks due to increased intermolecular bonding. Preliminary results of these physically assembled hydrogels have exhibited shear thinning behavior, as well as changes in modulus and yield point as a result of varying PZLY repeat length and peptide weight percent, respectively.

Non-chain extended peptide-polyurea hybrids as a platform for injectable gels

ACS Spring 2022

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