Tissue Engineering And Nanotheranostics

“9.61x6.69” b2815 Tissue Engineering and Nanotheranostics

Plasmonic Nanoparticles Application in Biosensor and Bioimaging 185

are behind the increased inelastic light scattering in SERS. The EM

mechanism arise from LSPR of plasmon nanoparticles and is the

dominant effect, while chemical enhancement mechanism come from

molecular charge­transfer interactions between the molecule and the

metallic surface.187,188 Since the SERs signal intensity is dominant by

EM, a common aim among many groups has been to develop sub­

strate with great EM field. These substrates contain single sharp struc­

tures like nanocresents, nanostars or couple structure with controllable

gap.^189 Graham et al.^190 developed a selective SERS detection method

to locate Raman dye within the interparticle gap region between plas­

monic nanostructures. The appearance of target in this method selec­

tively and reversibly turn the Raman signal on or off. Nam’s et al.^191

improves these methods by controlling interparticle gap at the

nanometer scale. They reported a high­yield synthetic method for

preparing SERS­active dimeric gold–silver core–shell with a nano­

dumbbell structure (Fig. 8(a)). In this structure, nanometer silver

shell was formed to engineer the nanogap between AuNPs

Fig. 8. Schematic SERS­based detection methods: (a) Nanogap­engineerable nano­
structures for single molecules detection by SERS. In this method, Ag shell can be
controlled at nanometer scale to finely engineer the Raman­signal­amplifying plas­
monic nanogap between two core–shell particles. (Reprinted with permission from
Ref. 191. Copyright 2009, NPG). (b) A scheme of gold nanostructures containing
approximately 1­nm interior nanogap. Raman dyes can be precisely located within
the gap and the number of modified dyes can be controlled. Reprinted with permis­
sion from Ref. 192. Copyright 2011, NPG.