UV-triggered Polymerization of Polycatecholamines Enables the Production of Organ-on-chips Inside a Biosafety Cabinet

Surface modification of microfluidic chips used for making organ on a chip (OOC) applications is often a time-consuming process, involving chip cleaning, ultraviolet (UV)-exposure, and steam sterilization. This work reports developing a simple, rapid, and cost effective method that can achieve photo activated polymerization and patterning of catecholamine materials on microfluidic chips in a single step using the UV light present in a standard biosafety cabinet. Polydimethylsiloxane (PDMS) microfluidic devices were filled with monomers of dopamine and norepinephrine, followed by exposure to UV light triggers polymerization of the material, which creates a highly viable surface for OOC applications. We examined the performance of these UV triggered surface coatings for creating three different kinds of OOCs, where microfluidic chips were bonded and modified in three different ways: i) conventional oxygen plasma bonded microfluidic chips filled with monomer solutions and then exposed to UV to modify the surface (Plasma bonded, polymer coated); ii) both the fluidic layer and glass substrate were exposed to UV to coat the functional layer and simultaneously allow adhesive proteins to bind the two pieces together (UV bonded, polymer coated); and iii) project the UV light through a mask to create fluid wall microfluidic channels on a polydimethylsiloxane (PDMS) substrate (projection coating). Cath.a.differentiated (CAD) cells seeded on UV-exposed polymer-coated surface in the three techniques showed significantly high cell viability, cell adhesion, proliferation, genetic expression, and they retained the functionality compared to uncoated PDMS. The UV-triggered surface modification technique uses a minimalist approach by using less equipment and existing infrastructure, such as a biosafety cabinet, for creating a functional OOC. This novel, simple, low-cost approach to reproducibly generating an organ-on-a-chip will facilitate the wider adoption of this technique. (c) 2020 Elsevier Ltd. All rights reserved.