Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 175-181).

Cell attachment is vital for the integration of biomaterials in the body. Surface modification using cell adhesive peptides, such as Arginine-Glycine-Aspartic (RGD), has showed promise for enhancing cell adhesion. Cell adhesion on glass and polyethylene glycol (PEGylated) surfaces modified with active RGD and Proline- Histidine-Serine-Arginine-Asparagine (PHSRN) peptides as well as inactive RDG and HRPSN control peptides was investigated in serum free conditions using three cell lines; NIH3T3 fibroblasts, MC3T3 pre-osteoblasts and C2C12 pre-myoblasts. Peptide attachment to glass surfaces was confirmed by x-ray photoelectron spectroscopy and contact angle measurements. Cell attachment and spreading was equivalent on all peptide and fibronectin coated glass surfaces and was significantly higher than on unmodified glass after 3 hours. Cell attachment to the peptide modified glass was reduced in the presence of soluble RGD and RDG peptides, indicating that cell attachment to these surfaces may be integrin mediated, but not specific for RGD. Inhibition of protein synthesis with cycloheximide revealed that endogenous protein synthesis did not influence the specificity of cell attachment to the peptide modified glass surfaces in all cell types within a 3 hour period. However, cycloheximide treatment inhibited cell spreading on the peptide modified glass surfaces, suggesting that proteins synthesis was required for spreading. Long term adhesion studies, within a 24 hour period, showed that all cell lines were able to remain attached to the peptide modified glass surfaces, while C2C12 and MC3T3 cells were also able to form focal adhesions during this period. Cell attachment to peptide modified PEGylated surfaces over a 3 hour period showed that NIH3T3 and C2C12 cells experienced significantly higher levels of cell attachment on the RGD modified surface compared to the other peptides. MC3T3 cells attached to all the peptide modified PEGylated surfaces to the same extent, suggesting that cell attachment to peptide modified PEGlyated surfaces, can be cell type dependent. In conclusion all the peptides were able to promote cell adhesion on glass surfaces in the absence of a PEG linker. In the presence of a PEG linker cellular response to the peptide surfaces was both peptide and cell type dependent.

Certain surface-active media can considerably influence the flow and fracture properties of the .solids they wet. The effects of various lubricating media on the sliding friction behaviour of diamond on soda-lime glass were studied in the present research. An experimental apparatus was constructed to slide a hemispherical diamond linearly and at constant speed across the surface of a Corning type 2947 soda-lime glass microslide and to measure the resultant friction force. Tests were conducted in a variety of liquid and gaseous media at sliding speeds ranging from 0.001 cm/sec to 0.4 cm/sec. As a base for comparison initial tests were conducted in a high vacuum — 8 at 4 x 10 ⁻⁸. The results showed that all the media enhanced material displacement from that observed in high vacuum. In addition, the friction force was observed to rise with displaced material. A simple theory was used to predict with reasonable agreement the results obtained in in vacuum and air only. The greatest increase in displaced material was observed in heptyl alcohol. Scanning electron micrographs of the friction tracks suggest that heptyl; alcohol softened the surface of the glass. This is in agreement with previous work. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

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