(713g) Effect of Deposition Methods On Cell-Releasing Properties of a Thermoresponsive Polymer

Stimuli responsive polymers (SRP) are of great interest in the bioengineering community due to their use in applications such as drug delivery and tissue engineering. One example of an SRP is poly(N-isopropyl acrylamide) or pNIPAM. This SRP has the capability of changing its conformation with a slight temperature change across its lower critical solution temperature (LCST), changing its relative hydrophilicity. When the polymer is tethered to a surface, mammalian cells grow and proliferate on the SRP above the LCST. Below the LCST, the cells spontaneously release as a confluent cell sheet, which can be harvested for cell sheet engineering purposes. Due to its functionality, tethering this SRP to surfaces such that it retains its thermoresponsive characteristic for cell release is a widespread technique. In this work, we assessed two methods of deposition: spin coating and plasma polymerization. Characterization of the surface chemistry of the pNIPAM substrates was done using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Topography as well as thickness of the films was analyzed via atomic force microscopy (AFM). Finally, thermoresponse was characterized using contact angle measurements and cell response above and below the LCST. From these results, we conclude that although both techniques are useful for releasing cells, the method with which pNIPAM is deposited onto the surfaces may dictate whether they are used for cell sheet engineering or simply for non-fouling substrates.