ABSTRACT
For the past 20 years, biosurface scientists have developed and refined their understanding of the physical/chemical aspects of “bioadhesion”. Living cells attach to solid synthetic substrata with varying efficiencies, as a function of cell type, suspending medium constituents, and substratum treatment. There is a significant need for a better understanding of the “selection rules” that can qualitatively and, perhaps, quantitatively relate the degree of cell retention on synthetic solid supports to controllable surface properties of those substrata. As an example, a detailed physical/chemical study is described, wherein Chinese Hamster Ovary (CHO-K1) cells were incubated with polystyrene (PS) and standard reference polyethylene (PE) modified to produce variations in surface chemical composition by radio-frequency-gas-plasma treatment (RFGPT). Air plasmas were applied over the substratum faces uniformly or in patterned arrays. All substrata were characterized by several surface analytical techniques. The retentive strengths of initially attached cells were assessed. CHO cells attached but remained round on untreated PS and control PE. Upon RFGPT, oxygen in the form of alcoholic (C–OH), carbonyl (C═O), and carboxyl (O–C═O) functional groups was introduced to the PS surfaces, resulting in increases in surface energy; CHO cell attachment was followed by full spreading; CHO cell growth rate was increased over control values. The ultraviolet component of RFGPT did not contribute to the observed surface modification of either polymer. Shear challenges of attached cells resulted in easy removal of all round cells (at rates of 91 s−1), whereas larger shear rates were required to remove spread cells. Cell removal occurred due to cohesive failures, leaving substratum-attached materials on the test surfaces.
