In vitro assessment of macrophage attachment and phenotype on polymerized phospholipid bilayers

Phosphatidyl choline (PC)-based materials have been found to be resistant to nonspecific protein adhesion in vitro. In this study, a PC-based planar supported phospholipid bilayer composed of 1,2-bis[10-(2′,4′- hexadienoyloxy)decanoyl]-sn-glycero-3-phosphocholine (bis-SorbPC or BSPC) was generated on piranha-treated silicon wafers by vesicle deposition. The bilayer was polymerized with redox initiation forming a stable 4-nm thick coating. Polymerized lipid bilayers (PLBs) were characterized and tested for uniformity, with ellipsometry and contact angle. Cellular adhesion and morphological changes in RAW 264.7 macrophages were investigated in vitro on PLBs and compared to bare silicon controls. Fluorescent and scanning electron microscopy were used to observe changes in cellular morphology. The PLBs showed much lower cellular adhesion than bare silicon controls. Of the cells that attached to the PLBs, a very low percentage showed the same morphological expressions seen on the controls. It is hypothesized that proteins adsorb to the defects in the PLBs, caused by incomplete polymerization, and this mediates the observed minimal cellular attachment and morphological changes.