(648h) Layer-By-Layer Assembled Thin Film Biomaterials As Porous Biomolecular Delivery Systems

Biomaterials capable of delivering controlled quantities of bioactive agents, while maintaining mechanical integrity, are needed for a variety of cell contacting applications. We describe here two strategies toward porous, polyelectrolyte-based thin films capable of controlled biomolecular loading and release. In one approach, termed "nanoparticle templating," films are formed via the layer-by-layer assembly of charged polymers and nanoparticles (NP), then chemically cross-linked to increase mechanical rigidity and stability, and finally exposed to tetrahydrofuran to dissolve the NP and create an intra-film porous network. In another approach, termed "solution shock," films are subjected briefly to an extreme acidic environment following LbL assembly, causing expansion and ultimately a spinodal-like breakup of the film into a porous structure. We report here on film structure and mechanics, on biomolecular agent loading and release, and on the behavior of cells cultured on these films. While both strategies yield mechanics and biomolecular agent loading that are suitable for applications such as tissue engineering, the solution shock method offers advantages in simplicity and controllability.