Natural composites such as wood, bone, marine shells and the elaborate structures built by silica-condensing microorganisms have provided much inspiration for the design and synthesis of artificial materials. Ultimately, it is single cells that contain the essential software and hardware to construct material systems optimized across multiple length scales. Unfortunately, useful strategies to control structure formation, for instance, at the level of single plant or diatom cells have proven challenging. Alternatively, tissue-derived cultured cells exhibit a nearly limitless range of morphological features in vitro, depending on phenotype and interactions with the surrounding environment. Yet, it is these cells' fragility that prohibits their direct use in the production of more durable functional materials. An ability to translate these forms into robust, engineered materials would provide new opportunities for the design and fabrication of hierarchical composites.In this work we describe such an approach, where soft biological surfaces are replicated in silica with nanometer precision?a process we term silica bioreplication (SBR). As described recently (PNAS, 2012, 109:17336-41), we show the scalability of this approach and its application across a wide range of animal cell types. Complete external and internal cellular structures?from the nano- to macro-scale?are captured and preserved in these composites following drying and high temperature processing allowing, for instance, shape preserving pyrolysis of cellular architectures to form conductive carbon replicas. Further, we apply this technique to multicellular tissues and whole organisms and show silica-stabilized structures are nearly identical to their starting template even after carbonization at 1000 �C. Finally, we employ the well-characterized sensitivity of human erythrocytes to chemical perturbation to generate libraries of non-spherical inorganic particles with tunable properties (e.g., surface energies, mesoporosity). This work allows the structural and behavioral malleability of cultured cells to be exploited in the development of robust and economical biocomposites with programmed structures and functions.

Silica bioreplication (SBR): Translating fragile structures into durable materials

247th National Meeting (2014)

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