Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry

Amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin filmswere deposited by reactive magnetron sputtering and optically characterized withspectroscopic ellipsometry. The films were exposed to human serum albumin and theadsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data theadsorbed amount of proteins was quantified in terms of surface mass density using de Feijter'smodel. The results indicated larger adsorption of proteins onto the amorphous films comparedto the films with a more ordered microstructure. Complementary studies with labeled HSAusing radioimmunoassay showed up to 6 times higher protein adsorption compared to theellipsometry measurement which partly might be explained by differences in surfaceroughness (from 0.3 to 13 nm) among the films. The elutability of adsorbed labeled HSAusing unlabeled HSA and sodium dodecyl sulphate was low compared to a silicon reference.In addition, the four types of films were incubated in blood plasma followed by antifibrinogen,anti-HMWK or anti-C3c revealing the materials response to complement andcontact activation. Three of the films indicated immunoactivity, whereas the amorphouscarbon showed less immunoactivity compared to a titanium reference. All films showedindications of a stronger ability to initiate the intrinsic pathway of coagulation, compared tothe reference. Finally, the surfaces bone bonding ability was investigated by examination oftheir ability to form calcium phosphate (CaP) crystals in a simulated body fluid, with a-CNxdepositing most CaP after 21 days of incubation.
Original Publication:Torun Berlind, Pentti Tengvall, Lars Hultman and Hans Arwin, Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry, 2011, ACTA BIOMATERIALIA, (7), 3, 1369-1378.http://dx.doi.org/10.1016/j.actbio.2010.10.024Copyright: Elsevier Science B.V. Amsterdamhttp://www.elsevier.com