Studying Cell–Surface Interactions In Vitro: A Survey of Experimental Approaches and Techniques - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 60

Fig. 16 a Time course of D|Z min | after seeding equal numbers of initially suspended NRK cells
on a polystyrene-coated quartz resonator at time point zero. The PS film on the resonator was
either left unmodified (open circle) or had been exposed to an argon plasma (filled circle) prior to
inoculation. The value of |Z min | at the beginning of the experiment was set to zero. (Mean ±
SEM,n C 5;T = 37 C). b Phase-contrast micrographs of NRK cells 10 h (1), 24 h (2) and 48 h (3)
after inoculation on unmodified PS (B1, B2, B3) and plasma-treated PS (C1, C2, C3)
4. A major contributor to the QCM signal of adherent cells is the actin cyto-
skeleton [ 66 ]. Taken together with point (2) above, it is the part of the actin
cytoskeleton associated with cell-surface junctions that contributes to the QCM
signal and can be probed by QCM experiments.
4.4.2 Biocompatibility Testing of Polymer Surfaces
In contrast to the electrochemical approaches described in the preceding section,
which are limited to conductive coatings of the electrodes with proteins or other
biomolecules, the QCM-based analysis of cell-surface interactions is also appli-
cable to polymeric, metallic or ceramic coatings of the resonator. Any of these
materials can be coated as a thin film on the resonator surface and then resonance
analysis is performed just as described above. The only requirements with respect
to material deposition are homogeneity and rigidity of the coating such that
no significant acoustic loss occurs within the adlayer, as this would reduce the
inherent sensitivity of the resonator for subsequent cell adhesion studies.
Figure 16 a shows the time course of attachment and spreading of NRK cells after a
single-cell suspension was seeded to confluence on a quartz resonator coated with
a thin layer of polystyrene (PS). Spreading kinetics are again mirrored in the
time course of D|Z min |. When initially suspended NRK cells are seeded on an
unmodified PS surface (open symbols), the minimal impedance D|Z min | shows only
a minor and transient increase, indicating that specific interactions between cells
and the underlying surface are not allowed to form. Apparently, the cells are not
able to attach and spread properly on this surface. By contrast, after a selective
hydrophilization of the PS surface by short-term exposure to an argon plasma, cell