Slide- and Micoarray-Based Biosensors Using Noble Metal Nanoparticles - From Bioimaging to Biosensors: Noble Metal Nanoparticles in Biodetection - page 66

Fig. 4.7) for LSPR sensing. 50 The optical characteristics of the gold-
capped nanoparticle layer substrate depend on the diameter of the
dielectric nanoparticles to form a layer and the thickness of the gold
layer on the dielectric nanoparticle layer, and may be attributed
to a similar phenomenon described for the plasmon resonance
spectra of the nanoshell-structured nanoparticles. 51 Such gold-
capped nanoparticle layer substrates have been used to detect DNA
hybridization 50 and antigen-antibody immunoreactions. 52
Figure 4.7 Construction of the multiarray LSPR-based nanochip. The
surface-modiied silica nanoparticles were aligned onto the
gold-deposited glass substrate surface. Subsequently, the
gold layer was deposited onto the silica nanoparticle layer.
Reprinted with permission from ref. 69, Copyright 2006,
American Chemical Society.
Gold nanoholes in metal ilms are other attractive metal
nanostructures for biosensing. Taking the advantage of its dual
optical properties, which combine the LSPR created by the
nanostructures with the surface plasmon polaritons in metal ilms, 53
nanoholes fabricated with colloidal lithography on thin gold ilms
have been reported for biosensing (see Fig. 4.8). 54,55 As a notable
aspect, the preferential occurrence of spontaneous-supported
phospholipid bilayers (SPB) formation on silicon-based substrates,
but not on bare noble metal surfaces, was found to induce the
rupture of phospholipid vesicles at the bottom of the nanoholes.
This self-assembly process allows the detection of biochemical
interactions conining exclusively inside the nanoholes, where the
electromagnetic ield enhancement induced by LSPR is maximized.
These experiments show that the sensitivity toward the detection of