Adhesion of Human U937 Monocytes to Nitrogen-Rich Organic Thin Films: Novel Insights into the Mechanism of Cellular Adhesion

We present a two-fold study designed to elucidate the adhesion mechanism of human U937 monocytes on novel N-rich thin films deposited by plasma- and VUV photo-polymerisation, so-called PVP:N materials. It is shown that there exist sharply-defined (critical) surface-chemical conditions that are necessary to induce cell adhesion. By comparing the film chemistries at the critical conditions, we demonstrate the dominant role of primary amines in the cell adhesion mechanism. Ouantitative real-time RT-PCR experiments using U937 cells that had adhered to PVP:N materials for up to 24h are presented, The adhesion induces a transient expression of cytokines, markers of macrophage activation, as well as a more sustained expression of PPAR gamma and ICAM-I.