Biased Pairing and DNA-based Docking of Two Different Types of Monodisperse Micrometer-Sized Liposomes in a Microfluidic Device

Recent advances in prototissue construction have highlighted the importance of organizing multiple artificial cells with distinct function and intercellular communication capabilities. Previous approaches, including the use of optical tweezers, phoresis driven by the magneto-Archimedes effect, and 3D-printing, enabled the aggregation of liposome-based artificial cells, but they lacked precise spatial organization of individual artificial cells for large-scale production. Microfluidic devices (MFDs) offer potential for high-throughput prototissue fabrication but have faced challenges in achieving precise ordering of fragile liposomes with diameters exceeding 1 µm. In this study, we demonstrated an MFD incorporating U-shaped microstructures designed for liposome trapping that enables stochastic liposome capture and release, with this process being influenced by differences in the mechanical properties of the liposomal membrane. Based on these findings, we developed a two-step loading strategy, involving the sequential introduction of two liposome types, and successfully arranged them within the trapping microstructures of the MFD. Furthermore, DNA modification of the liposomes enhanced their spatial proximity within the MFD, enabling DNA hybridization and strand displacement reactions between the adjacent liposomal membranes. This MFD platform provides a statistical assay for constructing and analyzing minimal prototissues composed of two heterogeneous micrometer-sized liposomes.