Tuning cell adhesion and growth on biomimetic polyelectrolyte multilayers by variation of pH during layer-by-layer assembly

Abstract

Polyelectrolyte multilayers of chitosan and heparin are assembled on glass where heparin is applied at pH=4, 9 and 4 during the formation of the first layers followed by pH=9 at the last steps (denoted pH 4+9). Measurements of wetting properties, layer mass, and topography show that multilayers formed at pH=4 are thicker, contain more water and have a smoother surface compared to those prepared at pH=9 while the pH=4+9 multilayers expressed intermediate properties. pH=9 multilayers are more cell adhesive and support growth of C2C12 cells better than pH=4 ones. However, pH 4+9 conditions improve the bioactivity to a similar level of pH=9 layers. Multilayers prepared using pH 4+9 conditions form thick enough layers that may allow efficient loading of bioactive molecules. Multilayers prepared from chitosan and heparin at pH=4 inhibit, while those prepared at pH=9 promote adhesion and growth of C2C12 cells. A combination of pH=4 during preparation of first 7 layers, with pH=9 of following 4 layers, results in multilayers that promote cell interactions. Such system may provide both high loading capacity for growth factors and promote adhesion of cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.