Figure 4: Chemical fingerprinting of gold nanoparticles in the interior of a chicken liver.

A mechanically fractured silica bioreplicated and carbonized (c-SBR) chicken liver imaged using secondary electron (SE) (a, scale bar, 50 μm) and backscattered electron detection (BSE) (b, scale bar, 50 μm) reveals gross morphology of the internal liver. The area within the dashed rectangle in a and b is expanded and imaged using SE (c, scale bar, 5 μm) revealing a fenestrated sinusoid (i), space of disse (ii) and hepatocyte (iii). This same region is imaged using BSE to reveal single 200-nm diameter AuNPs (d, scale bar, 5 μm; inset is a magnification of the centre bright spot). The spectrum in e was acquired from the centre particle (and representative of spectra obtained from other points denoted as ‘e’) and the spectrum in f was acquired from the region ‘f’ denoted in d. (e,f) Show relative intensities from single pixel acquisitions of >1,000 counts.