The layer-by-layer (LbL)
technique has been widely used to produce nanofilms for biomedical applications.
Naturally occurring polymers such as ECM macromolecules are attractive
candidates for LbL film preparation. In this study we assessed the build-up of
type I collagen (Col1)/chondroitin sulfate (CS) or Col1/Heparin (HN) on
polydimethylsiloxane (PDMS) substrates.
The build-up was assessed by quartz crystal microbalance with
dissipation (QCM-D) and atomic force microscopy (AFM). Integrin-mediated cell adhesion
was assessed by studying the cytoskeletal organization of mammalian primary cells
(chondrocytes) seeded on different end layers and number of layers. Data
generated from the QCM-D observations showed a consistent build-up of films with
more adsorption in the case of Col1/HN. Col1/CS films were stable in media
while Col1/HN were not. AFM analysis showed the layers were fibrillar in
structure for both systems and between 20-30nm thick. The films promoted cell adhesion when compared to
tissue culture plastic in serum free media with cycloheximide. Crosslinking of
the films resulted in constrained cell spreading and a ruffled morphology. Finally
beta1 integrin blocking antibodies prevented cell spreading, suggesting that
cell adhesion and spreading was mediated mainly by interaction with the
collagen fibrils. The ability to construct stable ECM-based films on PDMS has
particular relevance in mechanobiology, microfluidics and other biomedical
applications.
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