Biomedical Engineering Reference
In-Depth Information
Fig. 8.12
Measured proton NMR signal with the 1-chip system. (
a
) Water. (
b
) Water with
magnetic nanoparticles (0.05 mM) (From Ref. [
3
])
coil. In the absence of avidin (Fig.
8.13
, top), the particles stay uniformly dispersed,
yielding T
2
of 48 ms. In the presence of avidin (Fig.
8.13
, bottom), the biotinylated
magnetic particles bind to avidin to self-assemble into clusters [
9
]. The effectively
larger magnetic particles reduce T
2
to 40 ms [
9
]. The reduction in T
2
corresponds to
the detection of avidin. The palm system detects down to 1 avidin molecule in 600
million water molecules.
We use the 1-chip system to detect human chorionic gonadotropin (hCG), the
hormonal protein found in blood or urine (Fig.
8.14
). Its primary use for female
