Enhanced growth of human vascular endothelial cells on negative ion (Ag-)-implanted hydrophobic surfaces

Silver negative ions (Ag-) were implanted to an insulator, polystyrene, in a relatively low ion energy ranging from 5 to 30 keV, and in a dose ranging from 10(14) to 6 x 10(16) ions. cm-2. Surfaces of Ag--implanted polystyrene were studied by means of secondary ion mass spectrometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and micro-Raman spectroscopy, and contact angle measurement. As a result of Ag- implantation, the polystyrene surfaces underwent degradation, thereby becoming more hydrophilic with increasing dose and ion energy except an ion energy of 30 keV. The Ag- implantation in polystyrene led to enhanced growth of human vascular endothelial cells, which grew to more extent with increased hydrophilicity of Ag--implanted surfaces except an ion energy of 30 keV. Polystyrene surfaces on which Ag- were implanted up to an ion energy of 30 keV caused the same hydrophobic level as polystyrene surface itself. Nevertheless, the Ag--implanted polystyrene showed relatively good biocompatibility different from polystyrene. Such an improvement in cell adhesion may be related to the formation of a graphite-like structure on polystyrene surfaces by a Ag--implanted process. Moreover, upon plating in a high cell density, human vascular endothelial cells survived even on the polystyrene region of Ag--implanted polystyrene for longer than 1.5 months, while the cells did not grow on untreated polystyrene in the same culture conditions.