Figure 6.

Schematic of standard approaches (A and B) and our approaches (C and D) toward nanofilm biomaterials of independently controllable mechanical rigidity and bioactivity. A) Film is constructed via the layer-by-layer assembly of charged polymers and bioactive agents (see Figure 1), and subsequently chemically cross-linked to increase rigidity, often at the expense of bioactivity. B) Bioactive agents are added following film cross-linking, with loading typically limited to the film surface. C) The surface cross-linking strategy, where cross-links form between an activated polymer and previously deposited polymers, and are thus confined to the film surface, away from the bioactive species, resulting in a rigid outer skin and high biomolecular accessibility. D) The nanoparticle templating strategy, where film assembly and cross-linking occurs in the presence of nanoparticle templates, whose removal via dissolution results in a pore space that may be subsequently filled with biomolecules. Film rigidity is controllable by the extent of cross-link formation and bioactivity by the extent of biomolecular loading.