Analysis of Permeation and Release Behavior Based on Structural Differences in the Gelatin Network within Hydrogels

Living organisms exhibit unique functionalities through reversible structural transitions of biomacromolecular assemblies, enabling molecular recognition and selective permeability. Inspired by these systems, we investigated anisotropic and isotropic gelatin hydrogels as models to mimic the structural transitions of biological channels. Using a template-based method, anisotropic gelatin networks were formed with polypropylene and polyvinyl chloride templates, while isotropic networks were fabricated on glass substrates. Permeability studies with model molecules (phenylalanine, methylene blue, and rhodamine B) demonstrated that molecular properties (compound's balance between hydrophobicity and hydrophilicity) influenced transport behaviors, highlighting structural dependency. Mineralization experiments further validated the hydrophobic regions within anisotropic hydrogels, promoting silica formation while restricting calcium phosphate deposition. Additionally, drug release studies indicated anisotropic hydrogels preferentially released hydrophobic molecules, while isotropic hydrogels favored hydrophilic drugs. These findings elucidate the role of network anisotropy in the functions of hydrogel and provide insights into designing bioinspired functional materials for applications such as drug delivery systems and biomimetic membranes.