Chemistry-Induced Effects on Cell Behavior upon Plasma Treatment of pNIPAAM

In the field of bioengineering, depending on the required application, the attachment of various biological entities to the biomaterial is either favored or needs to be prevented. Therefore, different surfaces modification strategies were developed in combination with the characteristics of the materials. The present contribution reports on the use of the specific surface property of a thermoresponsive polymer poly(N-isopropylacrylamide) pNIPAAM obtained by spin coating in combination with plasma treatment for tuning cell behavior on treated polymeric surfaces. Topographical information for the plasma-treated pNIPAAM coatings obtained by Atomic Force Microscopy (AFM) measurements evidenced a more compact surface for Ar treatment due to combined etching and redeposition, while for oxygen, a clear increase of pores diameter is noticed. The chemical surface composition as determined by X-ray Photoelectron Spectroscopy showed the specific modifications induced by plasma treatment, namely strong oxidation for oxygen plasma treatment illustrated by eight times increase of O-C=O contribution and respectively an increase of C-N/O=C-N bonds in the case of ammonia plasma treatment. Structural information provided by FTIR spectroscopy reveals a significant increase of the carboxylic group upon argon and mostly oxygen plasma treatment and the increase in width and intensity of the amide-related groups for the ammonia plasma treatment. The biological investigations evidenced that L929 fibroblast cells viability is increased by 25% upon plasma treatment, while the cell attachment is up to 2.8 times higher for the oxygen plasma-treated surface compared to the initial spin-coated pNIPAAM. Moreover, the cell detachment process proved to be up to 2-3 times faster for the oxygen and argon plasma-treated surfaces and up to 1.5 times faster for the ammonia-treated surface. These results show the versatility of plasma treatment for inducing beneficial chemical modifications of pNIPAAM surfaces that allows the tuning of cellular response for improving the attachment-detachment process in view of tissue engineering.