Adhesion of different bacterial strains to low-temperature plasma treated biomedical silicon catheter surfaces

In this study, two different strains of five different bacteria were isolated and characterized. Contact angles were measured by a captive-bubble technique. Surface free energies were calculated from the contact angles and hydrophobicities were evaluated by p-xylene adhesion. The zeta potentials and surface charges of the bacteria were measured. The contact angles of the gram positive bacteria and gram negative bacteria were in the range of 48-69 degrees and 43.5-55 degrees, respectively. While corresponding surface free energies were in the limits of 45.4-51.6 erg . cm(-2) and 51.7-61.8 erg . cm(-2), respectively. The p-xylene adhesions were parallel to hydrophobicity defined by contact angles, and 32.2-80.3% and 2.3-36.6% for the gram positive bacteria and gram negative bacteria, respectively. The zeta potentials for these bacteria were from -650.2 to +17.5 mV and from -159.6 to -6.0 mV; respectively. Most of the bacteria were negatively charged, except the CNS-2 and CPS-1 strains. In the second part of the study, the attachment of these bacteria to Si(R) catheters and to DMAEMA and AAc plasma treated Si(R) catheters were investigated. The hydrophobic bacteria attached best to the hydrophobic Si(R) catheter. Both plasma treatments caused significant drops in bacterial attachment in most cases. The effects of AAc plasma treatment were more pronounced.