Description
The aim of this research is to develop a Lab-on-a-chip (LOC) platform for monitoring barrier models, in particular a skin barrier one, that could be used for testing personalize therapies. The LOC device comprehends two levels of microfluidics with integrated Organic Electrochemical Transistor (OECT) biosensors for monitoring in-situ the conditions of the in vitro cellular model and relevant biomarkers. OECT have been selected since they are able to work also in contact with wet environment and humidity for long periods. The first step was the design of the multi-layer microfluidic device in CAD, in details: i) a culture chamber with an additional layer for hosting a membrane, ii) two OECT inside a sealing layer to be in contact with the top and with the bottom parts, iii) a filling chamber for the lower part of the central membrane and iv) a microfluidic structure to allow connection between the culture medium and the OECT sensors. Two versions of the platform were designed to incorporate two different membranes for cell culture: a PolyCarbonate (PC) and a silk fibroin based. The two membranes were rispectively (38 ± 3) µm PC one and (210 ± 10) µm for the silk one. The designed platform was made in Polydimethylsiloxane (PDMS) using replica molding technique. The master molds were obtained in CAD software as the complementary of the different layers and 3D printed with a PolyJet technology (Stratasys J35), as well as the sealing plugs. The PDMS was casted on the molds and cured at 80°C for 2 hours and then extracted and the in/outlet obtained by punching. The three layers were bonded with plasma embedding the membrane. The OECT chips with the electrodes were fabricated in clean room environment and then completed in the additive manufacturing laboratory by the inkjet deposition of the channel material PEDOT:PSS, with three different values of the drop spacing (80, 100 and 120 µm). The characterization of the fabricated devices included leakage tests (by dyed PBS solution) and electrical measurements of the OECTs. The platform with PC membrane showed good results in terms of leakage and flow, while the one with silk membrane requires further optimization to avoid bending and leakages between the two layers through the membrane. A proof of concept of the biosensing capabilities of the integrated OECTs was performed by measuring the response of the devices to different concentrations of Ang2 in PBS solution, through gate functionalization with the corresponding antibodies. The future work will involve the optimization of the version of the platform with silk membrane to improve sealing and flow conditions, the seeding of an in vitro skin model on the membranes, the functionalization of OECT gates for specific biomarker detection, the characterization of the biosensor in that specific case and the real-time monitoring of cellular responses under various conditions. This work is part of the research activities funded by the Italian National Recovery and Resilience Plan (PNRR) within the Digital Driven Diagnostics, Prognostics and Therapeutics for Sustainable Health Care (D34HEALTH) Foundation.