Mesoporous Semi-Permeable Flexible Polyurethane Membranes: Advancing Bioartificial Pancreas Design for Type 1 Diabetes Treatment.

This study reports the development of elastomeric mesoporous polyurethane (PU) membranes for bioartificial pancreas applications in type 1 diabetes treatment. The membranes are designed to exhibit semi-permeable properties, enabling insulin diffusion while restricting larger immune molecules, such as immunoglobulin G (IgG). Although electrospinning is a widely used technique for fabricating porous membranes for controlled drug release, it typically results in an average pore size on the order of few micrometers, which is two orders of magnitude larger than the mesoporous scale required. In this work, a green-electrospinning process using waterborne PU suspension and poly(ethylene oxide) (PEO) is employed, followed by thermal annealing and washing steps. The resulting membranes exhibit a controlled pore size in the mesoporous range (≈20 nm measured by capillary flow porometry). Diffusion tests confirmed selective permeability, with a recovery rate of 25% for insulin and a recovery rate below 5% for IgG, meeting therapeutic needs. In vivo characterizations show no degradation and good biocompatibility of the membranes without chronic inflammation. Moreover, mechanical characterization demonstrates the membranes' flexibility and strength, making them suitable for minimally invasive surgical implantation. These findings underscore the potential of PU membranes for long-term biomedical applications, addressing critical challenges in permeability and mechanical stability.