Development of a Barrier-On-Chip model and fabrication of embedded high-resolution porous-membrane based electrodes to assess the integrity of the barrier

The human body possesses a large variety of barriers, of different origins and characteristics, playing an important role in the functioning of the organism. They are responsible for controlling some essential biological processes and maintaining homeostasis by regulating the interactions between the compartments that they separate. A possible disruption of the barrier can lead to important consequences. It can indeed be associated with severe diseases including multiple sclerosis in the case of disruption of the blood-brain barrier or disorders such as celiac disease in the case of loss of intestinal barrier integrity. Monitoring the status and integrity of a cell barrier is therefore crucial. In-depth analysis of the state of a cell barrier in laboratory requires the employment of accurate in vitro models able to mimic the corresponding in vivo environment with remarkable accuracy. To this purpose, the realization of an OOC (Organ-On-Chip) device capable to mimic a cellular barrier in vitro i.e., a Barrier-On-Chip device, and the fabrication of embedded high-resolution membrane-based gold electrodes to evaluate the integrity of the barrier performing TEER (Trans-Epithelial Electrical Resistance) measurements is proposed. These gold sensors fabricated on top of PET membranes allow for more reproducible and reliable measurements than the classical setup for measuring TEER, where readings are instead performed through chopstick electrodes in a Transwell system. In this study, a stable leakage-free method of manufacture of a dual-chamber PDMS device containing a thin microporous PET middle layer was proposed. The in vitro model was then validated under dynamic flow and static culture conditions of CACO-2 gut cells. Furthermore, a protocol optimization for the fabrication of the embedded membrane-based electrodes was also presented. Specifically, it is proposed a non-aggressive lift-off system to increase the manufacturing efficiency of the sensors. Finally, a proof-of concept in evaluating the integrity of an intestinal barrier in the absence and presence of compounds is also provided.