Hierarchical Assembly of Bioactive Amphiphilic Molecule Pairs into Supramolecular Nanofibril Self-Supportive Scaffolds for Stem Cell Differentiation.

Molecular design of biomaterials with unique features recapitulating nature's niche to influence biological activities has been a prolific area of investigation in chemistry and material science. The extracellular matrix (ECM) provides a wealth of bioactive molecules in supporting cell proliferation, migration, and differentiation. The well-patterned fibril and intertwining architecture of the ECM profoundly influences cell behavior and development. Inspired by those features from the ECM, we attempted to integrate essential biological factors from the ECM to design bioactive molecules to construct artificial self-supportive ECM mimics to advance stem cell culture. The synthesized biomimic molecules are able to hierarchically self-assemble into nanofibril hydrogels in physiological buffer driven by cooperative effects of electrostatic interaction, van der Waals forces, and intermolecular hydrogen bonds. In addition, the hydrogel is designed to be degradable during cell culture, generating extra space to facilitate cell migration, expansion, and differentiation. We exploited the bioactive hydrogel as a growth-factor-free scaffold to support and accelerate neural stem cell adhesion, proliferation, and differentiation into functional neurons. Our study is a successful attempt to entirely use bioactive molecules for bottom-up self-assembly of new biomaterials mimicking the ECM to directly impact cell behaviors. Our strategy provides a new avenue in biomaterial design to advance tissue engineering and cell delivery.