Fig. 3(b) shows the surface tensions of the PVP solutions with
the different concentrations. The surface tension of the PVP
aqueous solution decreased with the PVP concentration increasing,
whereas that in the PVP bovine serum solution increased
greatly. The largest decrease of the surface tension in the PVP
aqueous solutions was found between 0 and 5 wt% concentrations
(71.970.0712 mN/m vs. 67.770.0414 mN/m). On the contrary, the
surface tension of the PVP bovine serum solution increased significantly
during the PVP concentration increasing from 0 to
20 wt%.