Photoluminescence of Gold Nanoparticles and Their Applications to Sensing and Cell Imaging - From Bioimaging to Biosensors: Noble Metal Nanoparticles in Biodetection - page 205

of Escherichia coli ( E. coli ). Type 1 imbriae present on the surface
of Enterobacteriaceae, such as E. coli , are responsible for their
mannose- and mannoside-binding activities. Thus, incubation of
E. coli with the biofunctional Man-Au NPs yielded brightly
luorescent cell NCs. The relationship between the luminescence
signal and the E. coli concentration is linear over the range from
1.00 × 10 6 to 5.00 × 10 7 cells/mL ( R 2 = 0.96), with the LOD of E. coli
being 7.20 × 10 5 cells/mL (Fig. 9.11). In contrast to standard methods
for pathogen detection, which require up to 2 days for analysis, the use
of these luminescent carbohydrate-functionalized Au NDs allows the
presence of E. coli to be detected within as little as 3 h.
Figure 9.11 Luminescence spectra of Man-Au NPs (25 nM) used as
probes for the detection of E . coli (from 2.50 × 10 6 to 1.00
× 10 8 cells/mL). Inset (A): Visualization of Man-Au NPs (25
nM) in the (a) absence and (b) presence of E . coli (2.50 ×
10 8 cells/mL) upon excitation (365 nm) under a hand-held
UV lamp. Inset (B): Plot of luminescence intensity (545 nm)
versus E . coli concentration. Reprinted with permission
from Ref. 25.
9.6 Conclusion
Research on luminescent Au NCs and luminescent Au NPs is
attracting increasing interest. Great progress has been made in
understanding the fundamental size- and surface-dependence
of the optical properties of these Au nanomaterials, as well as in
developing sensitive and selective sensors from them. Nevertheless,
much work remains to be done to better understand and manipulate
their properties. For example, the luminescence properties of
luminescent Au NPs are different from those of Au NCs, but remain