Bioactivation of Plane and Patterned PDMS Thin Films by Wettability Engineering
This study shows how surface properties of polydimethylsiloxane (PDMS) thin films, such as wettability and cellular adhesive behavior, can be influenced by surface modification and patterning, to improve the suitability of such modified PDMS for biomedical applications. For that purpose, different types of PDMS (i.e., soft (S-) and hard (H-) PDMS) and differently patterned surfaces were prepared by a commercially available tool which is originally used to produce patterned PDMS stamps for substrate conformal imprint lithography. To increase surface wettability and cellular adhesive behavior, PDMS surfaces were modified by O2, Ar/O2, Ar, and forming gas (N2/H2) plasma treatment. It is shown that, especially, plasma treatment using N2/H2 is a promising method to modify PDMS surfaces towards enhanced wettability. Such modified PDMS surfaces exhibit water contact angle values (WCA) of nearly 0° and demonstrate enhanced attachment of melanoma cells. Differences between as-prepared and plasma-treated S- and H-PDMS can be observed, where H-PDMS shows smaller WCA than S-PDMS. Even plasma-treated PDMS surfaces, however, exhibit only temporary hydrophilicity, due to hydrophobic recovery. To overcome this problem, plasma-treated PDMS films were stored in ethanol and water, where low and constant WCAs for several months could be achieved. Finally, the influence of surface topography of different patterned PDMS thin films on the adhesion behavior of melanoma cells was investigated. It can be concluded that chemical as well as structural modifications of PDMS enable to gradually control the adhesive properties of cells on their surfaces. This has a high technological impact since regulated and topologically stable adhesion and repulsion of cells by their scaffolds has high potency for in vitro as well as in vivo applications.
KeywordsPDMS Hydrophilicity modification Surface patterning Biocompatibility Cell adhesion
We would like to thank Aaron Häring for preparing and analyzing of PDMS surfaces, Christian Matthus and Florian Stumpf for AFM analysis, and Philipp Singer for the SEM images. We are also grateful to Christian Maueröder for preparing and culturing of C57BL/6 mouse-derived B16F10 melanoma cells on PDMS. Additionally, we would like to point out the importance of the collaboration with Fraunhofer Institute for Integrated Systems and Device Technology (IISB), Germany, and the Department for Internal Medicine 3 and Institute of Clinical Immunology, University of Erlangen-Nuremberg, Germany.
- 2.Choi, H. G., Choi, D. S., Kim, E. W., Jung, G. Y., Choi, J. W., Oh, B. K. (2009). Fabrication of nanopattern by nanoimprint lithography for the application to protein chip. BioChip Journal, 3, 76–811.Google Scholar
- 4.Curtis, A. G. S., & Varde, M. (1964). Control of cell behavior: topological factors. Journal of the National Cancer Institute, 33, 15–26.Google Scholar
- 10.Rosenman, G., & Aronov, D. (2006). Wettability engineering and bioactivation of hydroxyapatite nanoceramics. 2006 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2006 Technical Proceedings, 2, 91–94.Google Scholar
- 11.Israelachvili, J. N. (2011). Intermolecular & surface forces (3rd ed.). San Diego: Elsevier Academic Press.Google Scholar
- 17.Gomathi, N., Sureshkumar, A., Neogi, S. (2008). RF plasma-treated polymers for biomedical applications. Current Science, 94, 1478.Google Scholar
- 21.Verschuuren, M. A. (2010). Substrate conformal imprint lithography for nanophotonics. Dissertation, Utrecht University.Google Scholar
- 26.Mittal, K. L. (2009). Contact angle, wettability and adhesion (Vol. 6). Leiden: VSP/Brill.Google Scholar
- 29.Pinto, S., Alves, P., Matos, C. M., Santos, A. C., Rodrigues, L. R., Teixeira, J. A., et al. (2010). Poly(dimethyl siloxane) surface modification by low pressure plasma to improve its characteristics towards biomedical applications. Colloids and Surfaces, B: Biointerfaces, 81, 20–26.CrossRefGoogle Scholar