Figure 3: Shape-preserving conversion of silica bioreplication tissues into conductive specimens.

(a) Schematic showing pyrolysis of a silicified heart into a carbonized silica replica. (b) SEM imaging (without conductive metal coating) of a heart carbonized at 1,000 °C (the background is subtracted for clarity; scale bar, 1 mm). (c,d) Show increasing magnification of an arterial wall (c, scale bar, 30 μm) and (d, scale bar, 5 μm) . (e) A crack in the top surface (indicated by arrow) reveals cellular and micro- (~1 μm) to nanoscale (~70 nm) extracellular fibres (f, scale bar, 5 μm). (g) A small opening in the side of the heart (indicated by arrow) reveals free-standing fibres and an interior chamber (h, scale bar, 10 μm). (i,j) Manual sectioning of a carbonized heart (dotted lines, j, scale bar, 1 mm) reveals the internal chambers (k). The two sections have been given false colour for clarity. Deep imaging into the area denoted by the arrow in k (l, scale bar, 50 μm) and further magnified (area in dashed rectangle in l) in m (scale bar, 5 μm) reveals surface bound cells ~1.5 mm within the tissue section (false coloured for clarity). (n–q) Increasing magnification of a sectioned carbonized liver shows internal vascularization and resolution of fibrous features (q, inset). (n–q) Scale bars, 250, 50, 10 and 1 μm, respectively.