Paper PB+BI+PS-MoA10
Low-Temperature Plasma Processing of Polymeric Materials for Biomedical Applications

Monday, November 7, 2016, 4:40 pm, Room 101A

Polymeric biomaterials are widely used in medical applications such as wound healing, drug release, and blood dialysis. For example, Tygon® and similar thermoplastics are chosen for these applications because of excellent mechanical strength and flexibility but often suffer from bacterial attachment and proliferation that ultimately leads to infection and fouling of the biomedical device. Biocidal agents can be incorporated into the polymer to actively eradicate bacteria, but it is difficult to ensure that biocidal action is localized at the material-biological interface. As a result, changing the surface properties of the polymer ensures a second mechanism by which to discourage bacterial attachment and growth. Plasmas are frequently used to alter the surfaces of biomaterials, most often by surface modification or deposition of a film to discourage bacterial attachment, while retaining the bulk properties critical to device performance. Specifically, H₂O (v) plasma treatment can enhance the compatibility of biomaterials by increasing hydrophilicity and altering surface chemistry; here, we demonstrate the use of this treatment method specifically for antibacterial materials. First, we have used H₂O (v) plasmas to tune the release of an antibacterial agent (NO) from drug-releasing polymers. Composition of treated drug-releasing polymers measured via X-ray photoelectron spectroscopy demonstrates a 100% increase in oxygen content and an associated increase in wettability, as observed via water contact angle goniometry. Compared to the untreated polymer, H₂O (v) plasma treated polymers had a delayed, but equally dramatic 8-log reduction in growth of both gram-negative Escherichia coli and gram-positive Staphylococcus aureus. Second, in a related study, we utilized plasma-enhanced chemical vapor deposition to deposit a film of 1,8-cineole, an antibacterial constituent of tea tree oil. Bacterial attachment and biofilm formation assays reveal significantly reduced growth of both bacterial strains on plasma polymerized cineole films. H₂O (v) plasma treatment of these materials will also be discussed. Furthermore, optical emission spectroscopy allows correlation of gas phase excited state species in our plasmas under various plasma conditions to the resulting 1,8-cineole film surface properties, thereby allowing for fine-tuning of film surface properties for deposition onto biomedically-relevant polymer structures such as 3D polycaprolactone scaffolds. Collectively, our studies of plasma processing of antibacterial materials demonstrate this technique is a valuable tool in the production of next generation biomedical devices.