C. Stavis, T. L. Clare, J. E. Butler, A. D. Radadia, R. Carr, H. Zeng, W. King,
J. A. Carlisle, A. Aksimentiev, R. Bashir, and R.J. Hamers.
Surface functionalization of thin-film diamond for highly stable and
selective biological interfaces.
Proceedings of the National Academy of Sciences, USA,
108:983-988, 2011.
STAV2011-AA
Carbon is an extremely versatile family of materials with a wide range of mechanical,
optical, and mechanical properties, but many similarities in surface chemistry. As one of
the most chemically stable materials known, carbon provides an outstanding platform for
the development of highly tunable molecular and biomolecular interfaces. Photochemical
grafting of alkenes has emerged as an attractive method for functionalizing surfaces of
diamond, but many aspects of the surface chemistry and impact on biological recognition
processes remain unexplored. Here we report investigations of the interaction of
functionalized diamond surfaces with proteins and biological cells using X-ray
photoelectron spectroscopy (XPS), atomic force microscopy, and fluorescence methods.
XPS data show that functionalization of diamond with short ethylene glycol oligomers
reduces the nonspecific binding of fibrinogen below the detection limit of XPS, estimated
as >97% reduction over H-terminated diamond. Measurements of different forms of
diamond with different roughness are used to explore the influence of roughness on
nonspecific binding onto H-terminated and ethylene glycol (EG)-terminated surfaces.
Finally, we use XPS to characterize the chemical stability of Escherichia coli K12 antibodies
on the surfaces of diamond and amine-functionalized glass. Our results show that
antibody-modified diamond surfaces exhibit increased stability in XPS and that this is
accompanied by retention of biological activity in cell-capture measurements. Our results
demonstrate that surface chemistry on diamond and other carbonbased materials provides
an excellent platform for biomolecular interfaces with high stability and high selectivity.
