Gene expression of primary mature bovine chondrocytes on 4-terminated and unmodified SiO2 surfaces. RNA was collected from cells after 3 days of culture on either tissue culture plastic (C), 4-terminated (C4), or unmodified SiO2 surfaces (SiO2) for the following genes A) Col2a1, B) Col1a2, C) Acan, D) Sox9, and E) Runx2. All genes of interest were normalized to Rpl13a. * denote significant differences (p<0.05).