UV-triggered polymerization of polycatecholamines enables the production of organ-on-chips inside a biosafety cabinet

Abstract

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.