Electrostatic Shielding Suppresses Nanoparticle Deposition and Enhances Plasma-Activated Biofunctional Coatings for Cell Culture Well Plates.

Abstract

Plasma-based surface treatments are increasingly used to functionalize cell culture substrates, enabling the covalent immobilization of biomolecules without chemical reagents. However, a hidden risk in such processes is the in situ formation of plasma-polymerized nanoparticles (PPNs), which can result in particulate contamination. These particles form in the plasma discharge and accumulate inside well plates, compromising surface uniformity, interfering with biomolecule presentation and confounding cell-based assay results. Here, we present a scalable electrostatic shielding approach using a 0.45 mm mesh Faraday cage to suppress nanoparticle deposition during plasma-activated coating (PAC) deposition of standard polystyrene well plates. This setup modulates the local plasma sheath and prevents nanoparticle entrapment inside the wells. We conducted detailed surface characterization, including XPS, zeta potential, wettability, radical retention, and optical analysis across mesh and without mesh configurations. Importantly, iPSC differentiation into cardiomyocytes was significantly improved on Faraday cage-treated PAC plates, with enhanced syncytial formation, prolonged contractility, and reduced interwell variability. Our findings highlight Faraday cage-assisted PAC as a practical and scalable method for producing clean, chemically functionalized cell culture surfaces. This strategy addresses an overlooked source of contamination in plasma-modified biomaterials and offers a robust platform for cell manufacturing, bioassays, and regenerative medicine.