Porous Nanofilm Biomaterials Via Templated Layer‐by‐Layer Assembly

Hydrogel-like biomaterials are often too soft to support robust cell adhesion, yet methods to increase mechanical rigidity (e.g., covalent cross-linking the gel matrix) can compromise bioactivity by suppressing the accessibility or activity of embedded biomolecules. Nanoparticle templating is reported here as a strategy toward porous, layer-by-layer assembled, thin polyelectrolyte fi lms of suffi cient mechanical rigidity to promote strong initial cell adhesion, and that are capable of high bioactive species loading. Latex nanoparticles are incorporated during layer-by-layer assembly, and following 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide/ N -hydroxysulfosuccinimide (EDC-NHS) cross-linking of the polyelectrolyte fi lm, are removed via exposure to tetrahydrofuran (THF). THF exposure results in only a partial reduction in fithickness (as observed by ellipsometry), suggesting the presence of internal pore space. The attachment, spreading, and metabolic activity of pre-osteoblastic MC3T3-E1 cells cultured on templated, crosslinked fi lms are statistically similar to those on non-templated fi lms, and much greater than those on non-cross-linked fi lms. Laser scanning confocal microscopy and quartz crystal microgravimetry indicate a high capacity for bioactive species loading (ca. 10% of fimass) in nanoparticle templated fi lms. Porous nanofi lm biomaterials, formed via layer-by-layer assembly with nanoparticle templating, promote robust cell adhesion and exhibit high bioactive species loading, and thus appear to be excellent candidates for cell-contacting applications.