Physicochemical and Cellular Analysis of Polydopamine for Use as an Orthopaedic Bioadhesive

Abstract

Polydopamine (PDA), a unique bioinspired polymer, has been a subject of interest in fields including orthopedic biomaterials and antibacterial surfaces. Its osteogenic effects and ability to control surface traits through precise variables (e.g., pH, temperature) have led to its use as a coating in the enhancement of a wide range of materials, including metals and ceramics. In this Thesis, two studies were carried out to better understand the capability and mechanism of PDA-mediated bioactivity. In the first study, we investigated whether PDA coatings can further enhance the bioactivity of nanoporous Titanium (NPTi). While physicochemical traits were in line with literature, PDA was effective in enhancing cell proliferation, beyond NPTi, as early as 8 hours with enhancement in cell spreading and focal adhesion prevalence as early as 1 hour. No changes in adsorptive capacity were found, suggesting a serum-independent component (SIC) of the surface. The second study was focused on (1) determining how treatment parameters influence the physiochemical makeup of PDA surfaces, (2) assessing how PDA surfaces influence stem cell behavior and (3) confirming and investigating the SIC of PDA effect. Results confirm that there is indeed a SIC of PDA coatings with enhancement in cell spreading that improves with the increased size and density of PDA particles. Our findings show that the SIC works in concert with circulating sera to elicit the bioactive effects of PDA. The novel rPDA surface, obtained by adding rotation during the coating deposition, is also shown to elevate bioactivity during normal culturing, beyond classical coatings, with ongoing work suggesting enhancement in the osteogenic differentiation of hMSCs. Taken together, this work has demonstrated novel aspects underlying the potential and mechanism of action for the bioactivity of PDA, ultimately providing new evidence supporting the use of PDA as a biomedical material.