Mechanisms of Decreased Bacteria Colonization on Polyether Ketone Ketone (PEKK)

Polyether ether ketone (PEEK) has been used extensively as an orthopedic and spinal implant device. Recently, it has been shown that substituting a ketone for an ether in the backbone of PEEK forming polyether ketone ketone (PEKK) can improve in vitro bone cell function and decrease bacteria functions without resorting to antibiotic use. However, the mechanism by which PEKK outperforms traditional orthopedic and spinal implants has not been elucidated to date. Since it is well known that initial protein adsorption controls bacteria attachment to implants, the objective of the present in vitro study was to determine the mechanism by which PEKK inhibits bacteria colonization. Results demonstrated that the presently fabricated PEKK possessed a large degree of nanoscale surface features which led to a surface energy that matched that of casein, mucin, and lubricin which are proteins known to reduce bacteria colonization. Further, when coating PEKK individually with casein, mucin, and lubricin, in vitro assays demonstrated significantly less MRSA, Staph. epidermidis , and Pseudomonas aeruginosa after 24 hours compared to PEEK. In addition, there were less live bacteria on the PEKK compared to PEEK. In this manner, this study provides the first mechanism of action for how PEKK decreases bacteria colonization as it showed that PEKK has a surface energy closer to that of proteins known to inhibit bacteria colonization. PEKK promotes the adsorption of such proteins to consequently decrease bacteria attachment and growth and thus should be further studied as a novel material that could potentially reduce orthopedic and spinal implant infection without resorting to antibiotic use.