(632e) Protein-Loaded Slanted Columnar Thin Films As Novel Biomaterials for Enhancing Cell-Surface Interactions

When fabricated by glancing angle deposition, slanted columnar thin films (SCTFs) consist of uniform nanocolumns, which possess intricate and complex architectures ranging in size from the sub-nano to micro-scales with precise intercolumnar spacing. Besides applications in photovoltaics, micro- and nano-fluidics, and nanoelectronics, such as field emitters, supercapacitors, and transistors, interest in SCTF applications have recently branched out to biomaterials and biosensing, although optimal cell culture conditions have not yet been established for these substrates. In addition, the influence of nanotopography, in particular uniform and intricately sculptured nanotopographies, on cell characteristics such as proliferation, morphology, and gene expression must be better understood to engineer effective and functional biomaterial substrates. In this work, SCTFs were investigated for their potential to load fibronectin within the intercolumnar void space of the SCTFs and to subsequently serve as nanohybrid biomaterial substrates to culture various mouse and human cell lines. A novel, combinatorial analytical approach – spectroscopic ellipsometry and quartz crystal microbalance with dissipation (SE/QCM-D) – was employed to dynamically characterize the adsorption processes and effective porosities of protein adsorption within the three-dimensional thin films. Interestingly, QCM-D, which measures both the adsorbate and coupled solvent, detected similar quantities of protein adsorption to both flat and nanostructured silicon (Si) surfaces (approx. 9-11 mg/m²), while SE, which measures only the adsorbate fraction, measured distinctly different adsorption amounts between flat (approx. 3 mg/m²) and nanostructured (approx. 6-7 mg/m²) Si surfaces. In addition, optical modeling was also able to reveal the percentage of protein residing within the intercolumnar pore space (approx. 80% of total modeled adsorbate fraction) as opposed to on top (approx. 20%) of the columnar thin film. These studies demonstrated that SCTFs are not simply coated with proteins, but rather the intercolumnar void spaces of the films are also infiltrated with proteins. Upon seeding cells, silicon SCTFs loaded with fibronectin support robust cellular morphological and proliferative characteristics in comparison to flat silicon control surfaces as well as tissue culture polystyrene. For example, analysis of live/dead staining revealed that the percentage of live cells seeded on SCTFs containing fibronectin is similar to live cell percentages for cells seeded on tissue culture polystyrene with a fibronectin coating (approx. 99%). Cells seeded on Si-SCTFs coated with fibronectin demonstrated an approximate 3-fold enhancement of adhered cell amount and cell surface area when compared to cells seeded on flat Si surfaces. Cells on Si-SCTFs with fibronectin also demonstrated enhanced morphological characteristics when compared to tissue culture polystyrene coated with FN, with an approximate 1.2 fold enhancement of both adhered cell amount and cell surface area. Substrate characterization and biocompatibility results indicate that SCTFs are capable of loading biomolecules, and when fabricated with biocompatible materials, such as silicon, SCTFs support robust cell adhesion, spreading, viability and proliferation. Besides a uniform nanotopography afforded by the SCTFs, the SCTF intercolumnar void space can provide niches to load and release biomolecules, such as proteins, therapeutic compounds, and DNA. Since SCTFs also inherently possess functional electrical, magnetic, and optical material properties, these substrates could have immense potential as functional biomaterials for tissue engineering, therapeutics, and biosensing.