TEM images of gold nanostars (A), pMBA-embedded
silver-coated gold nanostars (B), and silica-coated, pMBA-embedded silver-coated gold nanostars (C; scale bars are 100
nm). (D) SERS signal from pMBA-labeled gold nanostars
(dotted), the silver-embedded pMBA-labeled gold nanostars
(dashed), and the silica-coated silver-embedded pMBA-labeled gold nanostars (solid); 10 s acquisition, 0.65 mW laser
power. (E) UV/vis extinction spectra of the silver-coated nanostars
before (dotted) and after (solid) silica coating. (F) PpIX absorption
(dotted) and emission (solid) at 415 nm excitation. (G) Particle size
distribution of the silver-coated gold nanostars before (dotted) and
after (solid) silica coating.