Luminal Surface Plasma Treatment of Closed Cylindrical Microchannels: A Tool toward the Creation of On-Chip Vascular Endothelium

On-chip vascular
microfluidic models provide a great
tool to study
aspects of cardiovascular diseases in vitro. To produce such models,
polydimethylsiloxane (PDMS) has been the most widely used material.
For biological applications, its hydrophobic surface has to be modified.
The major approach has been plasma-based surface oxidation, which
has been very challenging in the case of channels enclosed within
a microfluidic chip. The preparation of the chip combined a 3D-printed
mold with soft lithography and commonly available materials. We have
introduced the high-frequency low-pressure air-plasma surface modification
of seamless channels enclosed within a PDMS microfluidic chip. The
plasma treatment modified the luminal surface more uniformly than
in previous works. Such a setup enabled a higher degree of design
freedom and a possibility of rapid prototyping. Further, plasma treatment
in combination with collagen IV coating created a biomimetic surface
for efficient adhesion of vascular endothelial cells as well as promoted
long-term cell culture stability under flow. The cells within the
channels were highly viable and showed physiological behavior, confirming
the benefit of the presented surface modification.