Fabrication of a flexible ECM supporting-membrane for organs-on-chip applications

Abstract

One of the most widely used structural Organ-on-Chip industry is Polydimethylsiloxane (PDMS). This material offers desirable features such as customizable mechanical properties, patterning , biocompatibility, optical transparency, permeability to gasses, viscoelasticity and hydrophicity. One example of OoC, the Cytostretch platform proposed at TU Delft, where different tissues can be cultured in one single OoC platform. Its PDMS membrane can inflate and deflate in a cyclic and controlled matter, introducing mechanical cues to the cell substrate, and cell-cell interactions. 3D stimulation and custom patterning of the surface has shown to affect cells fate, this network gives both mechanical support and optimal cues for a more accurate cell formation. A new material appeared in literature as a substitute for PDMS: a formulation of off-stoichiometry-thiol-ene PDMS (OSTE-PDMS) is a proposed as a substitute material for PDMS as it features similar characteristics as PDMS but without known issues such as absorption of molecules, swelling and gas leakage. This material offers a surface modified to allow a specific functional group to covalently bond with it. This physical bond between the layer ensures a transfer of the stimuli produced by the device directly into the cell culture inside the hydrogel. Hydrogels are widely used in the cell culturing industry, this material offers a 3D interface for biochemical and mechanical cues as well as a optimal environment for the cells to survive.
The goal of this project is to integrate an ECM supporting platform to a porous membrane made of OSTE-PDMS ensuring local adherence between layers. During this project a new material has been used to obtain a microporous thin membrane which has its surface modified to bond with thiol reactive hydrogels. Samples of PDMS, OSTE-PDMS and OSTE-PDMS+Hydrogels underwent tensile tests and were analyzed and compared to literature showing results to be not similar in value but same behavior as in literature.UV cured and chemically induced hydrogels were tested during this project to physically bond with the modified OSTE-PDMS surface, both of the hydrogels proved to be possible candidates as both were successfully bonded to a OSTE-PDMS substrate in a petri dish. During the project the chemically induced hydrogel was prefered out of the two hydrogels due the its success in bonding to a OSTE-PDMS patterned and suspended membrane. This hydrogel has better mechanical properties, not UV dependant and has a quicker curation time making it a great option for future projects.