Nano‐Roughness‐Mediated Macrophage Polarization for Desired Host Immune Response

Macrophage polarization is a significant event in the host immune response, which can be modulated by modifying the surface of a biomaterial. Previous studies have demonstrated the modulation of macrophage polarization using different surface features; however, none of these studies reflect the effect of surface properties on unstimulated macrophage polarization for a prolonged period. To better understand the impact of surface features, in this work differentiated THP‐1 cells are employed to control macrophage polarization on nano‐rough surfaces for a duration of 7 days. Model nano‐rough substrates are fabricated by immobilizing gold nanoparticles (AuNPs) of predetermined sizes (16, 38, 68 nm) on a 2‐methyl‐2‐oxazoline thin film, followed by tailoring the outermost surface chemistry. All modified surfaces support high levels of cell adhesion and proliferation. Over time, the expression of pro‐inflammatory cytokines decreases, whereas the expression of anti‐inflammatory cytokines increases on all modified surfaces. Similarly, pro‐inflammatory interleukin (IL)‐1β gene expression is downregulated, and anti‐inflammatory IL‐10‐gene expression is upregulated, regardless of the surface roughness. Analysis of cell morphology reveals that the predominant cell type on the modified surfaces exhibits M2 anti‐inflammatory phenotype. Herein, how surface features can modulate macrophage responses over an extended period is highlighted, offering insights for the development of future biomaterial implants.