Fig. 1. Bilayered nanoshell formation on a single yeast cell. (A) Exposure of a cell (i) to a solution containing l-cysteine-coated gold nanoparticles, (ii) yielding a cell with a biohybrid layer, followed by self-assembly of silica, (iii) yielding a bilayered nanoshell. Artificial colors were used in the SEM micrographs (the scale bar equals 1 μm). Authentic micrographs can be found in Fig. S1.† (B) Sequential steps in the formation of a bilayered nanoshell: (i) a yeast cell surface possessing abundant hydroxyl groups and sparsely distributed amino groups and carboxyl groups, (ii) a biohybrid layer composed of amino-covered gold nanoparticle groups and carboxyl groups (yellow dots and blue layers represent gold nanoparticles and l-cysteine molecules, respectively), and (iii) the silica outer surface, exposing hydroxyl groups. Red dashed lines represent hydrogen bonding between functional groups on the cell surface with the biohybrid layer and functional groups of the biohybrid layer with the amorphous silica layer, as indicated in the lower part.