Atmospheric Pressure Plasma Functionalization of Sealed PDMS Microfluidics: Application to Capillary Pumping and Enhanced Cell Growth.

Microfluidic devices serve as essential tools across diverse fields like medicine, biotechnology, and chemistry, enabling advancements in analytical techniques, point-of-care diagnostics, microfluidic cell cultures, and organ-on-chip models. While polymeric microfluidics are favoured for their cost-effectiveness and ease of fabrication, their inherent hydrophobic properties necessitate surface functionalization, often post-sealing. Here, we introduce a versatile apparatus for functionalizing sealed microfluidic devices using atmospheric plasma processing, with a focus on PDMS (polydimethylsiloxane) microfluidics. Through meticulous analysis of surface properties and capillary velocity, before and after plasma treatment, along with a comparison between vacuum and atmospheric plasma functionalization methods, we demonstrate the efficacy of our approach. Subsequent experimentation within 3D PDMS microfluidic chambers, combining atmospheric pressure plasma treatment with collagen coating to facilitate mesenchymal stem cells (MSCs) growth over five days, reveals enhanced initial cell adhesion and proliferation, highlighting the potential of our method for improving cell-based applications within microfluidic systems.

Is There a Threshold in the Antibacterial Action of Superhydrophobic Surfaces?

The realization of antibacterial surfaces is an important scientific problem, which may be addressed by the use of superhydrophobic surfaces, reducing bacterial adhesion. However, there are several limitations and contradicting reports on the antibacterial efficacy of such surfaces. Moreover, achieving antibacterial action through minimization of adhesion does not ensure complete protection against bacteria. Here, we identify the important factors affecting antibacterial action on superhydrophobic surfaces, emphasizing the role of bacterial concentration, and observing an upper concentration threshold above which antibacterial action of any surface is compromised. Finally, we propose metal enriched, superhydrophobic surfaces, as the "ultimate" "hybrid" antibacterial surfaces for in vitro applications.