Block Sequence Effects on the Self-Assembly Behaviors of Polypeptide-Based Penta-Block Copolymer Hydrogels

Abstract

Peptide-based hydrogels have great potential for applications in tissue engineering, drug delivery, and so on. We systematically synthesize, characterize, and investigate the selfassembly behaviors of a series of polypeptide-based penta-block copolymers by varying block sequences and lengths. The copolymers contain hydrophobic blocks of poly(γ-benzyl-Lglutamate) (PBG, B x ) and two kinds of hydrophilic blocks, poly(L-lysine) (PLL, K y ) and poly(ethylene glycol) (PEG, EG 34 ), where x and y are the number of repeating units of each block, where PBG and PLL blocks have unique functions for nerve regeneration and cell adhesion. It shows that a sufficient length of the middle hydrophilic segment capped with hydrophobic end PBG blocks is required. They first self-assemble into flower-like micelles and sequentially form transparent hydrogels (as low as 2.3 wt %) with increased polymer concentration. The hydrogels contain a microscale porous structure, a desired property for tissue engineering to facilitate the access of nutrient flow for cell growth and drug delivery systems with high efficiency of drug storage. We hypothesize that the structure of B x -K y -EG 34 -K y -B x agglomerates is beyond micron size (transparent), while that of K y -B x -EG 34 -B x -K y is on the submicron scale (opaque). We establish a working strategy to synthesize a polypeptide-based block copolymer with a wide window of sol−gel transition. The study offers insight into rational polypeptide hydrogel design with specific morphology, exploring the novel materials as potential candidates for neural tissue engineering.

Cellular and Molecular Insights into the Divergence of Neural Stem Cells on Matrigel and Poly-l-lysine Interfaces

“…These interfaces not only provide a conducive microenvironment for NSC growth but also play a crucial role in determining the molecular signaling and fate of NSCs . Therefore, they also serve as essential components in composite materials for interface optimization. , However, the specific effects of these interfaces on the molecular and cellular behavior of NSCs are not well understood. This knowledge gap hinders the informed coating selection for various research objectives and could potentially affect result consistency across studies using different substrates.…”