(497d) Effect of Polymer Deposition Method On Thermoresponsive Films and Resulting Cellular Behavior

The thermoresponsive polymer poly(N-isopropyl acrylamide), or pNIPAM, has been widely studied for use in bioengineering applications. The polymer's unique capability to undergo a sharp property change near physiological temperatures makes it ideal for biomaterials. At physiological temperatures (37 ºC), the polymer is relatively hydrophobic and collapsed, allowing mammalian cells to attach and proliferate on the surface. When the temperature is shifted to room temperature (~25 ºC), the polymer swells, which causes the spontaneous release of biological cells from substrates. Currently, there are many methods to deposit pNIPAM onto substrates, including atom transfer radical polymerization (ATRP) and electron beam ionization. Each method yields pNIPAM-coated substrates with unique surface characteristics, which can influence cell behavior. In this work, we compare two methods of pNIPAM deposition: plasma deposition and co-deposition with a sol gel. The resulting pNIPAM films were analyzed for use as substrates for mammalian cell culture. Film integrity was based on surface characterization using XPS and ToF-SIMS, while thermoresponsive characteristics were verified using AFM and contact angles. As the primary purpose for these films is mammalian cell culture, cell attachment/detachment studies and an analysis of exocytosis function using carbon-fiber microelectrode amperometry (CFMA) were used to verify appropriate cell response. We find that, although both methods are useful for the deposition of functional pNIPAM films, plasma deposition is much preferred for cell-sheet engineering applications due to the films' thermoresponse, minimal change in cell density, and maintenance of supported cell exocytosis function.