oil and water: long lasting insulin infusion sets and more
How do oil and water mix? Well, they don’t. But this property of insolubility can be harnessed to fabricate some really unique structures named bijels (bicontinuous interfacially jammed emulsion gels). These bijel structures can be used as templates for biomaterials enhancing tissue integration and vascularization, potentially allowing for longer-wear insulin infusion sets.
When creating a material suitable for implantation into the body, not only do the chemical characteristics of the material need to be considered, but the physical properties also need to be understood. The reaction to foreign materials is known as the foreign body response (FBR). Ways to mitigate the FBR include creating carefully designed porous materials, many of which have pore networks with high degrees of connectivity. However, narrow connections between these pores with sharp edges may disrupt cell migration; thus, introducing bijels with fully-interpenetrating, non-constricting, uniform negative Gaussian curvature as an alternative. In other words, these materials are smooth-sailing with pores that are similarly sized and smooth all the way throughout the material.
Researchers at UC Irvine create bijels by adding appropriate levels of water, 2,6-lutidine (oil), and mutual wetting particles. When heated just right, the system arrests (or jams) and the particles line the oil-water interfaces. These water-oil templates are then used to make solid bijel materials, such as polyethylene glycol (PEG).
When PEG materials were implanted in nude mice, researchers found that:
- Bijel templated materials (BTM) had higher blood vessel area than particle templated materials (PTM)
- Blood vessels in BTMs were larger than those in PTMs
- CD206+ (pro-healing macrophage marker) macrophages were more prevalent in BTMs compared to PTM
UCI researchers are hoping to use this material to coat insulin infusion sets, allowing them to remain longer in the body due to reduced FBR and enabling faster insulin delivery due to the enhanced vascularization of the material.
But that’s not all; bijel templated materials have also shown favorable conditions for cell delivery applications, making it a potential method for transplanting islets into the body.
Main Takeaway: Bijels have potential to do a lot of things, from making long-lasting infusion sets to vascularized implants for islet cell transplantation. The possibilities are endless.
- McDevitt, K. M., Thorson, T. J., Botvinick, E. L., Mumm, D. R., & Mohraz, A. (2019). Microstructural characteristics of bijel-templated porous materials. Materialia, 7, 100393. https://www.sciencedirect.com/science/article/pii/S2589152919301899
- Thorson, T. J., Gurlin, R. E., Botvinick, E. L., & Mohraz, A. (2019). Bijel-templated implantable biomaterials for enhancing tissue integration and vascularization. Acta biomaterialia, 94, 173-182. https://pubmed.ncbi.nlm.nih.gov/31233892/
- Thorson, T. J., Botvinick, E. L., & Mohraz, A. (2018). Composite bijel-templated hydrogels for cell delivery. ACS biomaterials science & engineering, 4(2), 587-594. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6294128/