Long-term adsorption of fetal bovine serum on H/O-terminated diamond studied in situ by atomic force microscopy

We investigate adhesion of fetal bovine serum (FBS) on diamond surfaces which have alternating H/O-terminated surface patterns of 30 μm width prepared by hydrogen and oxygen plasma. The samples are immersed into 15% FBS in McCoy's 5A supporting medium and characterized by in situ atomic force microscopy (AFM) during 6 days of adsorption. Within the first day, 2-4 nm primary layer is formed on both H-/O-terminated surfaces. After 6 days, we observe 17 ± 5 nm FBS layer on O-terminated surface and 35 ± 5 nm layer on H-terminated surface. Adhesion of the primary and secondary layer is weaker on H-terminated surface. We present a model of FBS protein layers on H-/O-terminated diamond and we discuss implications for a preferential cell growth on O-terminated diamond. We also show that the preferential cell growth is not affected by the long-term FBS pre-adsorption.