Fig. 2
From: Enhanced calcium ion mobilization in osteoblasts on amino group containing plasma polymer nanolayer
Surface characterization—the zeta potential—of different chemical compositions. Note that the zeta potential of the Ti + PPAAm indicated a positive surface charge, whereas collagen type-I coating (Ti + Col) and the control surfaces (Ti and IBIDI) exhibited a negative charge. The cell physiological pH 7.4 is indicated. (SurPASS™ system, Anton Paar, n = 3)