| Determining cell
growth on crystalline surfaces of different orientations |
A
collaborative effort between the Rohrer and Dahl groups
examines the growth, adhesion, proliferation and
morphology of cells on inorganic substrates of
different crystallographic orientations. Given
the chirality of most biological molecules and
the sensitivity of cells to the presentation of
their extracellular environment, we expect some
degree of selectivity of the cells for the orientation
of the substrate. The REU student will prepare
coarse-grained copper and titanium substrates (grain
sizes greater than 100 mm) with flat surfaces.
A surface oxide will then be grown at elevated
temperature. The crystal orientations will be determined
by electron backscattered diffraction and the surface
roughness of each grain will be measured by atomic
force microscopy. After sterilization, cells will
be grown both on bare surfaces and surfaces coated
with extracellular matrix (ECM) peptides or proteins.
Indirect immunofluorescence and/or incorporation
of fluorescent ECM conjugates will be used to determine
the effect of surface orientation on protein adsorption.
We will test live cells for proliferation, apoptosis,
spreading and general morphology using a combination
of propidium iodide (to label dead cells) Hoechst
33342 (cell permeable nuclear stain) and Oregon
Green Wheat Germ Agglutinin (labels cell borders).
We can also use indirect immunofluorescence or
transfected exogenous rDNA of GFP-paxillin to visualize
adhesion to these crystal faces and compare with
adhesion assays such as washing or centrifugation.
These fundamental results will provide invaluable
information for the design of metallic implants
intended either to promote or inhibit cell adhesion
and growth in the body. |
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