Biodetection Based on Resonance Light Scattering of Noble Metal Nanoparticles - From Bioimaging to Biosensors: Noble Metal Nanoparticles in Biodetection - page 163

result, a strong RLS signal occurs in the resonance region of the Au
NPs. The RLS intensities characterized at 553 nm is proportional to
the concentration of captopril over the range of 0.1-1.7 mg/L with
the detection limit ( S / N = 3) of 32.0 μg/L. This approach is useful
to determine captopril in pharmaceutical preparations with the
recovery of 97.0-104.5% and RSD less than 2.4%.
Figure 8.1 Relative RLS intensity as a function of thiamazole/13 nm
diameter Au NPs (mol/L) ratio, with the same concentration of
thiamazole (0.14 mM) and the Au NP concentration being 1.57,
2.36, 3.14, and 3.93 nM, respectively. Each sample was placed
for 15 min before scanning and λ RLS = 555 nm. Reprinted from
Ref. 27 with permission.
RLS techniques are also popular for determination of small
analytes in cells. One representative example is the determination and
distribution of GSH within erythrocyte cells using Nile Red-absorbed
32 nm Au NPs. 31 When the Nile Red product is displaced by GSH on
the Au NP surface, the luorescence of the solution increases and the
Au NPs aggregate, which results in increased RLS signals. Figure 8.2
displays the phase contrast, dark-ield scattering, and luorescence
images of single erythrocytes. Representative scattering images of
these three cells are presented in Fig. 8.2B, in which the bright spots
illustrate the presence of Nile Red-absorbed 32 nm Au NPs within
the cells. Figure 8.2C presents one representative luorescence image
(the upper cell in Fig. 8.2B), which indicates that the displacement
and aggregation of Nile Red-absorbed 32 nm Au NPs induced by GSH
occurs in a manner similar to the occurrence of those processes in