Comparison of Nonthermal Plasma Processes on the Surface Properties of Polystyrene and Their Impact on Cell Growth

The initial adhesion and spreading of cells are crucial factors for the successful performance of a synthetic biomaterial used for cell culture disposables or human medical devices (e.g., implants). Surface properties which allow the control of the attachment of cells are decisive for the acceptance of the provided material. Hence, different surface preparation techniques are used to equip surfaces with functional groups to improve initial surface interactions. In this paper, polystyrene (PS) surfaces were modified by using different nonthermal plasma processes. In particular, low-pressure plasma and atmospheric-pressure plasma were applied to modify surfaces or to deposit thin films on surfaces. Furthermore, the behaviors of human osteoblastic cells with respect to cell viability and cell growth on differently plasma treated PS surfaces are investigated. A comparison is made between plasma-grafted PS and commercially available PS-such as tissue-culture PS and Primaria. The cell studies were accompanied by surface analysis comprising atomic force microscopy, determination of surface energies, and X-ray photoelectron spectroscopy measurements. This work demonstrates that the functionalization of PS substrates by applying low-pressure and atmospheric-pressure plasma processes are equally effective in the improvement of cell attachment and proliferation. Furthermore, it is shown that the enhanced metabolic activity and spreading behavior of osteoblastic cells correlate well with an increase in surface wettability and the introduction of polar oxygen-and/or nitrogen-containing functional groups after plasma treatment.