Protein adsorption to oligo(ethylene glycol) self-assembled monolayers: experiments with fibrinogen, heparinized plasma, and serum.
Low protein adsorption is believed advantageous for blood-contacting materials and ethylene glycols (EG)-based polymeric compounds are often attached to surfaces for this purpose. In the present study, the adsorption of fibrinogen, serum, and plasma were studied by ellipsometry on a series of well-defined oligo(EG) terminated alkane-thiols self-assembled on gold. The layers were prepared with compounds of the general structure HS-(CH2)15-CONH-EGn, where n = 2, 4, and 6. Methoxy-terminated tri(EG) undecanethiol and hydroxyl-terminated hexadecanethiol self-assembled monolayers (SAMs) were used as references. The results clearly demonstrate that the adsorption depends on the experimental conditions with small amounts of fibrinogen adsorbing from a single protein solution, but larger amounts of proteins from serum and plasma. The adsorption of fibrinogen and blood plasma decreased with an increasing number of EG repeats and was temperature-dependent. Significantly less serum adsorbed to methoxy tri(EG) than to hexa(EG) and more proteins remained on the latter surface after incubation in a sodium dodecyl sulfate (SDS) solution, indicating a looser protein binding to the methoxy-terminated surface. All surfaces adsorbed complement factor 3 (C3) from serum and plasma, although no surface-mediated complement activation was observed. The present study points to the importance of a careful choice of the protein model system before general statements regarding the protein repellant properties of potential surfaces can be made.
Benesch
J
J
Department of Physics and Measurement Technology, Linköpings Universitet, Linköping, Sweden. johbe@ifm.liu.se
Svedhem
S
S
Svensson
S C
SC
Valiokas
R
R
Liedberg
B
B
Tengvall
P
P
D000327:Adsorption; D019855:Ethylene Glycol / Q000737:chemistry* / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism*; D006046:Gold; D006493:Heparin / Q000737:chemistry; D006801:Humans; D008956:Models, Chemical; D010949:Plasma / Q000166:cytology*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
D012967:Sodium Dodecyl Sulfate; D006046:Gold; D005340:Fibrinogen; D006493:Heparin; D019855:Ethylene Glycol