Bioconjugation of Noble Metal Nanoparticles and Their Applications to Biolabeling and Bioimaging - From Bioimaging to Biosensors: Noble Metal Nanoparticles in Biodetection - page 22

for T 1 and T 2 contrast enhancement ( r 1 = 3 × 10 4 mM −1 s −1 and r 2 =
1.82 × 10 6 mM −1 s −1 ). For in vivo MR imaging, Au 3 Cu 1 nanocapsules
were examined in a series of MR imaging studies using BALB/c
mice (a dosage of 20 mg kg −1 ) with an injection in the tail vein.
Figures 2.5B ( T 1 -weighted imaging) and 2.5C ( T 2 -weighted imaging)
shows the monitor of pre- and post-contrast images using Au 3 Cu 1
nanocapsules. In T 1 -weighted images (Fig. 2.5B), immediately after
the injection (post 0 h), the region of the cardiac chamber was
brighter in axial and coronal views. After 2 h of circulation, the heart
area appeared brighter. Color mapping of the identical MR images
also provided evidence of MR signal changes: the light blue color in
the cardiac region expanded 2 h after the injection. Taking anatomic
T 2 -weighted images of mice (Fig. 2.5C), the T 2 -weighted imaging

(A) a) a)

(C) c) c)

(B) b) b)

Figure 2.5 (A) Au 3 Cu 1 nanocapsules as contrast agents in animal MR
imaging. In vivo progressive MRI events and color maps. (B)
T 1 -weighted and (C) T 2 -weighted images of male BALB/c mice
at the indicated temporal points (pre-injection, immediately
postinjection, and 2 h postinjection) in this experiment with
Au 3 Cu 1 nanocapsules. The arrows in (C) indicate the increase
in signal intensity and show visualized vessels for the thorax
and liver regions in T 2 -weighted images (coronal view).
[Reprinted with permission from ref. 54. Copyright 2007
American Chemical Society]. See also Color Insert.