Adhesion of human leukocytes on mixtures of hydroxyl‐ and methyl‐terminated self‐assembled monolayers: Effect of blood protein adsorption

Abstract

The adhesion of human leukocytes to nanostructured surfaces with different chemical properties and the effect of protein adsorption were investigated. Self-assembled monolayers (SAMs) prepared with mixtures of methyl- and hydroxyl-terminated alkanethiols in different percentages on gold were used. The surfaces were pre-immersed in distinct protein solutions (human serum albumin, human fibrinogen, and autologous plasma). Adherent leukocytes were analyzed both by light and SEM. SAMs submitted to pre-immersion in plasma presented higher numbers of adherent leukocytes in the pure OH-terminated SAM, whereas methyl-terminated surfaces accounted for the lowest number of adherent cells. We observed a general increase in the number of adherent human leukocytes as the percentage of OH groups on the surface of the SAMs increased for all the pre-immersion conditions investigated. The number of adherent human leukocytes is highly influenced by the pre-immersion conditions used, and this observation is particularly relevant in the case of the methyl-terminated SAMs. The results obtained demonstrate that surface chemistry has a major influence in leukocyte adhesion to biomaterials, and that pre-immersion in protein solutions has a determinant effect in leukocyte adhesion.

Discovery of hemocompatible bacterial biofilm-resistant copolymers

“…Only a weak correlation between leukocyte attachment and IgG adsorption was observed. This contrasted with findings of previous literature studies, which reported that fibrinogen, rather than IgG, promoted leukocyte adhesion [ 50 , 51 ] although differences in the conformation of adsorbed proteins that may influence cellular interactions cannot be ruled out [ 11 ].…”

Interactions of leukocytes and platelets with poly(lysine/leucine) immobilized on tetraethylene glycol-terminated self-assembled monolayers

“…However, the number of adherent leukocytes on EG4-SAMs was lower than on other SAMs previously studied by us (CH 3 -, OH-and COOH-terminated SAMs) [30] and by other authors [31]. Interestingly, surfaces with terminal OH groups showed very high leukocyte adhesion.…”

“…Concerning the increased density of CH 3 groups with increased leucine, previous results demonstrated that, in contrast to platelet adhesion, leukocyte adhesion is lower on CH 3 -terminated SAMs than on other terminal functional groups such as OH [30,31] and COOH [31].…”

“…A possible explanation for the different leukocyte adhesion behavior on these surfaces is that during pre-immersion in plasma proteins have 30 min to adsorb and get displaced by other proteins with higher affinity for the surface. On surfaces only pre-immersed in PBS protein adsorption was almost immediately followed by leukocyte adhesion because proteins were added together with the leukocyte culture medium [30].…”

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“…One reason for this is the relative ease in which one can make a well-ordered layer that can be tailored to suit the needs of the experiment. These can be bilayers, 1-5 self-assembled monolayers 6,7 or supported/tethered bilayers, using the integration of other molecules as supports distancing the layer from the surface. 8,9 The adaptability of the approach has led to exciting new developments in bio-nanotechnology 10,11 and in the design of novel characterization methods for investigating membrane protein-lipid interactions and antimicrobial peptides.…”