Superhydrophobic Cell-Repellent Microstructures: Plastron-Mediated Inhibition of A549 Epithelial Cell Adhesion

Control of cell adhesion is essential for biomedical devices, biosensors, and anti-fouling coatings. Here, adhesion of A549 epithelial cells is systematically evaluated on silicon substrates with tunable wettability (superhydrophilic to superhydrophobic) and topography (smooth, nanostructured, and micropillared). Superhydrophobic surfaces stabilize a trapped air plastron that minimizes solid-liquid contact, enabling plastron-mediated physical repellency of cells. The most cell-repellent surface, composed of 5 µm micropillars with a 7.4% solid-liquid contact fraction, reduced cell density by ≈83% versus a smooth hydrophobic control and ≈95% versus a hydrophilic control at 4 h, and by ≈90% and ≈93%, respectively, after 24 h of incubation, corresponding to an approximate tenfold decrease in cell adhesion. Micropillar arrays outperform nanostructures in resisting cell attachment, owing to large air-filled gaps exceeding 10 µm that physically prevent cell adhesion. A trade-off is observed: lower solid-fraction micropillars provide greater short-term repellency but lose the plastron over time, enabling delayed fouling, whereas higher-fraction structures preserve the air layer beyond 72 h but are initially less cell-repellent due to higher effective cell contact area and smaller air gaps. These results establish that optimized microscale superhydrophobic textures achieve superior and time-dependent bio-repellency and introduce a rational design strategy for non-fouling materials.