The combination of complex biopolymers and graphenes represents vast new possibilities for designing high performance hybrid bionanocomposite materials with unique properties, tunable functionality, and potential biocompatibility. However, design of such nanocomposites with specific properties requires a fundamental understanding of the intricate folding behavior of the biopolymer at the interfacial surface. In this work, we elucidate the interfacial interactions between silk fibroin (SF) and graphene oxide (GO) and demonstrate how these interactions can be modified by matrix chemistry and mechanical stress. These interfacial interactions were examined using high resolution atomic force microscopy (AFM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). We considered graphene materials ranging from fully-oxidized GO to fully chemically reduced GO (rGO). Molecular dynamics simulations of analogous systems were used to probe the interfacial forces contributing to the conformational behavior and corroborate FTIR and AFM observations. AFM images show SF having stretched fibrillary morphology on GO flakes versus a coiled network on reduced GO. FTIR spectra indicate that SF in the presence of GO prefers a crystalline structure with high crystalline β-sheet content, whereas SF tends to a more amorphous, random-coil structure at rGO surfaces. Molecular dynamics simulations suggest reduced van der Waals interactions between silk and GO surface stabilizes the SF native β-sheet dominant structure while enhanced van der Waals interactions lead to reduce β-folding and more disordered secondary structures.

Silk fibroin secondary structure on various graphene oxide substrates

251st National Meeting (2016)

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