Degradable 3D-Printed Hydrogels Based on Star-Shaped Copolypeptides

Abstract

We present a star copolypeptide-based hydrogel ink capable of structural microfabrication using 3D extrusion printing. The material comprises an amphiphilic block copolymer structure of poly(benzyl-l-glutamate)- b-oligo(l-valine), which spontaneously forms hydrogels through hydrophobic interactions. The chemical design allows the bulk phase of the hydrogel to remain intact after application of shear due to its self-recovery behavior. It is demonstrated that the composition of the materials is ideally suited for 3D printing with scaffolds capable of maintaining structural cohesion after extrusion. Post extrusion UV-triggered fixation of the printed structures is carried out, resulting in stable hydrogel constructs. The constructs were found to be degradable, exhibited favorable release of encapsulated molecular cargo, and do not appear to affect the metabolic health of the commonly used fibroblastic cell line Balb/3T3 in the absence of the reactive diluent N, N'-methylenebis(acrylamide). The star copolypeptide inks allow for rapid prototyping enabling the fabrication of defined intricate microstructures, providing a platform for complex scaffold development that would otherwise be unattainable with other processing techniques such as molding or casting.

Recent advances in shear‐thinning and self‐healing hydrogels for biomedical applications

“…More recently, a star copolypeptide‐based hydrogel bioink was formed from poly(benzyl‐ l ‐glutamate)‐b‐oligo( l ‐valine) amphiphilic block co‐polymer due to hydrophobic interactions stemming from the self‐assembly of the valine domains for 3D bioprinting applications . The constructs were further stabilized via UV‐treatment for secondary crosslinking and were found to exhibit favorable release of encapsulated cargo and were not found to be cytotoxic to balb/3T3 cells.…”

Extrusion 3D Printing of Polymeric Materials with Advanced Properties

“…Furthermore, the release of the encapsulated molecular cargo could be achieved using a novel 3D printed degradable polypeptide–hydrogel construct. [ 254 ] The hydrogel inks were designed with star architecture to facilitate formation of hydrogels through self‐assembly of the valine domains at the point‐like junctions. The 3D printed hydrogels were degraded when immersed into an isotonic media, with a variety of controlled pH values, due to the deconstruction of polypeptide units and ester bonds.…”

Self‐Healing Supramolecular Hydrogels for Tissue Engineering Applications

“…Although PAs are biocompatible and bioactive, due to the expense of large scale peptide production, it became necessary to develop cost‐effective, scalable systems. Amphiphilic block copolymers that self‐assemble based on hydrophobic interactions have been utilized for drug delivery, cell‐encapsulation, cartilage regeneration, and 3D bioprinting . Recently, an injectable star PEG‐b‐poly (propylene sulfide) scaffold for wound repair was reported .…”