Paul M Maschhoff, Benjamin M Geilich, Thomas J Webster

There has been a significant and growing concern over nosocomial medical device infections. Previous studies have demonstrated that embedding nanoparticles alone (specifically, zinc oxide [ZnO]) in conventional polymers (eg, polyvinyl chloride [PVC]) can decrease bacteria growth and may have the potential to prevent or disrupt bacterial processes that lead to infection. However, little to no studies have been conducted to determine mammalian cell functions on such a nanocomposite material. Clearly, for certain medical device applications, maintaining healthy mammalian cell functions while decreasing bacteria growth is imperative (yet uncommon). For this reason, in the presented study, ZnO nanoparticles of varying sizes (from 10 nm to >200 nm in diameter) and functionalization (including no functionalization to doping with aluminum oxide and functionalizing with a silane coupling agent KH550) were incorporated into PVC either with or without ultrasonication. Results of this study provided the first evidence of greater fibroblast density after 18 hours of culture on the smallest ZnO nanoparticle incorporated PVC samples with dispersion aided by ultrasonication. Specifically, the greatest amount of fibroblast proliferation was measured on ZnO nanoparticles functionalized with a silane coupling agent KH550; this sample exhibited the greatest dispersion of ZnO nanoparticles. Water droplet tests showed a general trend of decreased hydrophilicity when adding any of the ZnO nanoparticles to PVC, but an increase in hydrophilicity (albeit still below controls or pure PVC) when using ultrasonication to increase ZnO nanoparticle dispersion. Future studies will have to correlate this change in wettability to initial protein adsorption events that may explain fibroblast behavior. Mechanical tests also provided evidence of the ability to tailor mechanical properties of the ZnO/PVC nanocomposites through the use of the different ZnO nanoparticles. Coupled with previous antibacterial studies, the present study demonstrated that highly dispersed ZnO/PVC nanocomposite materials should be further studied for numerous medical device applications.