The adsorption of high density lipoproteins (HDL) on polyethylene (PE)
, poly(2-hydroxyethyl methacrylate) (poly(HEMA)), polyesterurethane (P
U), Biomer, and mica surfaces was studied. The adsorption of HDL from
a single protein solution and a plasma solution on the surfaces showed
that the amount of adsorbed HDL was not related to the hydrophobicity
(or hydrophilicity) of the surfaces. It was observed that the amount
of HDL adsorbed on PE increased with increasing HDL concentration of a
single protein solution until 5 mu g/ml, and increasing plasma concen
tration resulted in an increase of HDL adsorption. In addition, HDL ad
sorption from an HDL solution of 500 mu g/ml on PE reached a maximum w
ithin a few minutes at 25 degrees C. Only a propertion of adsorbed HDL
could be desorbed when the adsorbed layers were incubated with Tween
20 or sodium dodecyl sulfate (SDS), while the desorption was dependent
on the nature of the surfaces. It was more difficult to desorb HDL ad
sorbed from plasma to PE than to desorb HDL adsorbed from a single pro
tein solution to PE. It was found that the desorption of adsorbed HDL
from PE by the detergents was decreased if the protein layer had been
stored in buffer (pH 7.4) for 24 h before desorption, while a higher s
toring temperature had a negative effect on the desorption of the lipo
protein from the surface. Adsorbed HDL on mica in a physiological buff
er was imaged by a tapping mode atomic force microscope (AFM). The sur
face appeared to be covered by single HDL proteins as well as clusters
of two or three HDL proteins with an average height of 5 to 6 nm. Fur
thermore, the partial desorption of adsorbed HDL from mica was confirm
ed by AFM measurements. (C) 1996 Academic Press, Inc.