Leukocyte adhesion on model surfaces under flow: Effects of surface chemistry, protein adsorption, and shear rate

The effect of specific chemical functionalities on the adhesion of polymorp honuclear leukocytes (PMNs) under flow was investigated using a set of well -characterized, chemically functionalized surfaces prepared by self-assembl y of alkanethiolate monolayers on gold surfaces. Terminal functionalities i ncluded CH3, CH2OH, COOH, and (OCH2CH2)(3)OH groups. A new surface modifica tion was used to incorporate a phosphorylcholine moiety on the hydroxyl-ter minated monolayer. Surface modification was verified using contact-angle me asurements, ellipsometry, and X-ray photoelectron spectroscopy. Adhesion on the surfaces was studied in the presence and absence of preadsorbed fibrin ogen. Fibrinogen adsorption on self-assembled monolayers (SAMs) was quantif ied using radioisotope detection. PMN adhesion was found to be dependent on the monolayer's terminal functionality. Adhesion was higher on the hydroph obic CH, surface and the polar COOH monolayer. Leukocyte adhesion was least on the phosphorylcholine-rich surface, followed by the ethylene-oxide-cont aining monolayer. Cell adhesion also was low on the hydrophilic OH monolaye r. Attachment was decreased with increasing shear rate, exhibiting a three- fold decrease between 20 and 100 s(-1). Fibrinogen adsorption was higher on the CH, monolayer but comparable for the other four SAMs. Preincubation of the surfaces with fibrinogen decreased adhesion on all SAMs examined. (C) 2000 John Wiley & Sons, Inc.