Fig. 1

Artist’s impression of silicon dioxide diatom shells, which appear as micrometer cylinders with an average diameter of d~8 μm and heights larger than h > 10 μm, arrays of pores decorate the external surface of the diatoms (a). SEM micro-graphs of silica shells functionalized with gold nanoparticles (D24 systems) acquired at low (b) and high (c) magnifications factors. From these, one can observe the regular pattern of pores permeating the diatom surface decorated with randomly distributed gold nanoparticles, with a pore size ~200 nm and a particle size ~20 nm. Large field SEM (d) and optical (e) images of D24 systems assess the functionalization process capability to produce large volumes of micro-devices. Fluorescence microscopy inspection of D24 systems after incubation with fluorescent 50 nm yellow microspheres reveal devices selectivity, specificity and sensitivity (f)