granules (0.2 cc, n = 6) were soaked into 2 mL of
medium composed of minimal essential medium-alpha (a-MEM; Gibco, Invitrogen,
U.K.) supplemented with 10% fetal bovine serum (FBS, Lonza, Germany)
and 1% penicillin/streptomycin (Gibco, Invitrogen, U.K.), and incubated
at 37 °C in a humid atmosphere with 5% CO2 for 4 days.
After washing three times with phosphate buffer solution (PBS, Invitrogen,
Darmstadt, Germany), 0.5 mL of 1% Triton solution was added to each
sample. Thereafter the amount of protein detached from the samples
into the Triton solution was measured with the QuantiPro BCA Assay
Kit (Pierce Biotechnology Inc., Rockford, U.S.A.) following the manufacturer’s
instructions, and absorbance was measured with a spectrophotometer
(Anthos Zenyth 3100, Anthos Labtec Instruments GmbH, Salzburg, Austria)
at 620 nm. A calibration curve was prepared using standard FBS solutions.
The amount of proteins adsorbed onto the ceramics was then converted
to the same amount of the material (1.0 cc) and expressed as mean
± SD.