Page 561 - Book Hosokawa Nanoparticle Technology Handbook

27 DEVELOPMENT OF THE THERMORESPONSIVE MAGNETIC NANOPARTICLE APPLICATIONS

Cl - + NH 2 aq. NaCO 3 / ether O
+ Cl H 3 N NH 2
N
O O
H O
O O
H HN NH H DPPA / TEA / DMF HN NH H
+
-
N NH 3 Cl + H OH H H H
S N N S
O O
O O
Figure 27.3
Synthesis schemes of N-acryloyl glycine amide and a biotin derivative.
Biotin
Avidin

Biotinylated compound

Thermoresponsive
magnetic nanoparticle

Biotinylated compound

S Substrate
A T G C A T
Biotin P Product
Nucleic acid
Antibody Enzyme

Figure 27.4
Immobilization of a biomolecule to a thermoresponsive magnetic nanoparticle using the biotin–avidin interaction.

contain biotins, these thermoresponsive magnetic The following sections introduce specific applica-
nanoparticles can specifically form bonds with tions of Therma-Max to the biotechnology field.
avidins and a variety of biological molecules, such as
biotinylated proteins and DNAs, through the biotins
on the particle surface (Fig. 27.4). 4. Application examples of the thermoresponsive
The thermoresponsive magnetic nanoparticles do magnetic nanoparticles to the biotechnology field
not settle spontaneously at room temperature and can-
not be separated magnetically, even by using a fairly (1) Application to the diagnosis field
strong magnet. However, when placed in an ice bath, Due to its easy separation from the sample after con-
they instantly coagulate and can be easily separated necting antigens, the magnetic nanoparticle coupled
magnetically (Fig. 27.5). Moreover, the coagulated with antibodies is a diagnosis agent of some potential.
particles can be made to revert to a completely dis- Fig. 27.6 shows a typical example of an antigen detec-
persed state by raising the temperature. As just tion method via a sandwich method using the anti-
described, the thermoresponsive magnetic nanomole- body-coupled magnetic nanoparticles.
cules can be stored as a completely uniform solution, In case specific antigens exist in the sample, these
but can rapidly coagulate to become magnetically will be adsorbed by the antibody-coupled magnetic
separable by applying heat, rendering them a suitable nanoparticles. Following the adsorption, the labeled
material for a variety of automatic rapid analyses. antibodies (secondary antibodies) are added and the

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