Smart Materials for Manipulating Cell/Surface and Cell/Cell Interactions

Poly(N-isopropyl acrylamide) (pNIPAM) undergoes a sharp property change in response to a moderate temperature drop. When the polymer is maintained above its lower critical solution temperature (LCST, ~32 °C), most biological cells are observed to adhere. However, below its LCST, confluent cell sheets are found to detach intact--and without the use of harsh treatments usually required for cell removal. This “smart” behavior has generated great interest in the biomaterials community. Previously, we demonstrated radio frequency (rf) plasma to be a one-step, solvent-free surface modification method that is compatible with any surface chemistry or geometry. These characteristics make this technique useful for cell and tissue culture, which often rely on plastic tissue culture plates. During Year 1 of our PREM funding, we constructed an rf plasma reactor (top left) for the deposition of pNIPAM films. In addition, we have characterized the resulting films using X-ray photoelectron spectroscopy for film composition, interferometry for film thickness, contact angles for thermoresponse, and cell detachment for cell releasing properties. As demonstrated with bacterial cell cultures of Halomonas marina (middle and bottom left), the materials fabricated using this reactor retain their “smart” behavior. Reed, et al., “Thermally Responsive Cell Culture Substrata for Systems Biology and Drug Discovery,” presented at the NSF/EPSCoR NM Regional Conference, December 1, 2006, 1st place for best student poster. Lucero, et al., “Construction and Characterization of an RF Reactor to Create Plasma Polymerized Thermoresponsive Coatings,” presented at the AVS New Mexico Chapter Symposium and Exhibition, May 21-25 2007, 1st place for best student poster.