Micromachining of Polyurethane Membranes for Tissue Engineering Applications

Engineered tissue barrier models offer in vitro alternatives in toxicology and disease research. To mimic barrier tissue microenvironment, a porous membrane that can approach the stiffness of physiological basement membranes is required. While several biocompatible membranes with micrometer range thickness (10 pm) and a stiffness less than polystyrene (3 GPa) or polyethylene (PET, 2 GPa), have been developed, there has been little effort to optimize the process to enable rapid and reproducible pore production in these membranes. Here, we investigate the use of laser irradiation with femtosecond (fs) pulses because the combination of high-precision and cold ablation causes minimal damage to polymeric membranes. This process enables automated, high-throughput and reproducible fabrication of thin, microporous membranes that can be utilized to culture cells at air liquid interface (ALI), a unique culture technique that simulates the tissue-barrier microenvironment. We show the optimization of laser parameters on a thin polyurethane membrane and patterned pores with an average diameter of 5 pm. Tissue was cultured at ALI for 28 days to demonstrate the membrane's utility in constructing a tissue barrier model. These results confirm the utilization of fs laser machining as a viable method for creating a porous barrier substrate in tissue engineering platforms.