Interface-engineered Caco-2 cell culture on a collagen-coated liquid–liquid interface in a microfluidic device

Epithelial tissues form selective barriers essential for physiological homeostasis. Conventional in vitro models rely on solid substrates, which limit the physicochemical flexibility of the cellular microenvironment. Here, we introduce a microfluidic platform in which a collagen-coated liquid–liquid interface formed between perfluorocarbon (FC-43) and culture medium serves as a substrate for epithelial cell adhesion. By culturing Caco-2 cells in the device, we show that the liquid interface supports cell attachment and the formation of monolayers. Immunofluorescence observation reveals the development of tight junctions and organized actin cytoskeletons, indicating early-stage epithelial maturation. Our new microfluidic system enables the formation of stable liquid–liquid interfaces that serve as viable and flexible substrates for epithelial cell culture, offering new opportunities for multiphase microfluidic models of epithelial barriers.