Braiding Anisotropic Hydrogels: A phase, microstructural, and mechanical study

Anisotropic hydrogels find widespread applications in biomedical engineering, particularly as scaffolds for tissue engineering. However, producing them without multi-step synthesis procedures or specialized equipments, remains a challenge. In this study, we explore using disodium cromoglycate (DSCG), a lyotropic chromonic liquid crystal (LCLC), to template PEG in a self-assembly process. By formulating DSCG with short-chain PEGDA (Mn=250), we fabricated anisotropic hydrogel networks of fibrin-like morphology. The origin of this structure arises from a reaction-diffusion process, as PEGDA is depleted from the bulk and recruited to the surface of the DSCG as the polymerization takes place. To understand the formulation space, we constructed DSCG-PEGDA-water three-component phase diagrams to examine the influence of crowing agent PEGDA on DCSG phase behaviors. Through precise control of DSCG concentration, we modulate pore sizes of the hydrogel networks. Furthermore, by employing an in-situ active microrheology characterization platform, we quantify elastic moduli of hydrogels across PEGDA concentrations. The ease of access to PEG precursors with different chain lengths and architectures, their inherent flexibility in tuning the mechanical properties, coupled with their biocompatibility and biodegradability, underscores anisotropic hydrogels’ potential use in addressing challenges related to cell encapsulation and as a model system to study the cell-environment reciprocity.