Silk film culture system for in vitro analysis and biomaterial design.

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment (1,2). These materials are desirable because they possess highly controllable dimensional and material characteristics, are biocompatible and promote cell adhesion, can be modified through topographic patterning or by chemically altering the surface, and can be used as a depot for biologically active molecules for drug delivery related applications (3-8). In addition, silk films are relatively straightforward to custom design, can be designed to dissolve within minutes or degrade over years in vitro or in vivo, and are produce with the added benefit of being transparent in nature and therefore highly suitable for imaging applications (9-13). The culture system methodology presented here represents a scalable approach for rapid assessments of cell-silk film surface interactions. Of particular interest is the use of surface patterned silk films to study differences in cell proliferation and responses of cells for alignment (12,14). The seeded cultures were cultured on both micro-patterned and flat silk film substrates, and then assessed through time-lapse phase-contrast imaging, scanning electron microscopy, and biochemical assessment of metabolic activity and nucleic acid content. In summary, the silk film in vitro culture system offers a customizable experimental setup suitable to the study of cell-surface interactions on a biomaterial substrate, which can then be optimized and then translated to in vivo models. Observations using the culture system presented here are currently being used to aid in applications ranging from basic cell interactions to medical device design, and thus are relevant to a broad range of biomedical fields.