Diamond is recognized as an attractive material for merging solid-state and biological systems. The advantage of diamond field-effect transistors (FET) is that they are chemically resistant, bio-compatible, and can operate without gate oxides. Solution-gated FETs based on H-terminated nanocrystalline diamond films exhibiting surface conductivity are employed here for studying effects of fetal bovine serum (FBS) proteins and osteoblastic SAOS-2 cells on diamond electronic properties. FBS proteins adsorbed on the diamond FETs permanently decrease diamond conductivity as reflected by the −45 mV shift of the FET transfer characteristics. Cell cultivation for 2 days results in a further shift by another −78 mV. We attribute it to a change of diamond material properties rather than purely to the field-effect. Increase in gate leakage currents (by a factor of 4) indicates that the FBS proteins also decrease the diamond–electrolyte electronic barrier induced by C–H surface dipoles. We proposed a model where the proteins replace ions in the very vicinity of the H-terminated diamond surface.
Schematic model of the interface between surface conductive diamond SG-FET channel and the cell medium containing proteins and cells. Schematic electric field distribution and characteristic dimensions across the interface are shown along the right side.
1Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16200 Prague 6, Czech Republic
2Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, 12852 Prague 2, Czech Republic
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