Biomedical Engineering Reference
In-Depth Information
O
O
C
O
C
O
NH-(CH 2 ) 2 -NH 2
C
OH
C
HO
2 HN-(CH 2 ) 2 -HN
1a
1b
O
O
C
C
NH-(CH 2 ) 2 -NH 2
OH
Amide group
2b
CH 2 OH
HOH 2 C
1a: conc. H 2 SO 4 /HNO 3 at a 3:1 ratio, sonicate for 3h at 40
°
C
1b: ethylenediamine+HATU, sonicate for 4h at 40 ° C
2b: Lithium aluminum hydride(LiALH4)+THF, sonicate for 2h at RT
2c: Phthalimide+THF+DEAD, sonicate for 2h and stirred for 3h
2d: Trifluoroacetic acid(TFA), sonicate for 3h.
CH 2 OH
2c
O
O
CH 2 -N
CH 2 NH 2
N- 2 HC
O
2 HNH 2 C
O
2d
O
CH 2 -N
CH 2 NH 2
O
Amine group
FIGURE 12.13
Schematic illustration of the reaction scheme to form SWCNT with amino functionalization: 1a and 1b shows the
direct amide functionalization while 1a-2d shows the amine functionalization of the SWCNT. (From
Ramanathan, T., Fisher, F. T., Ruoff, R. S., Brinson, L. C. (2005). Amino-Functionalized Carbon Nanotubes for
Binding to Polymers and Biological Systems. Chem. Mater., 17, 1290-1295.)
For designing sensing systems based on biofunctionlized CNTs for protein biorecogni-
tion, it is important to prevent nonspecific binding and at the same time introduce selec-
tive and specific binding probes. Surfactant-aided functionalization and poly(ethylene
glycol) (PEG) [78] or polyethylene imine (PEI) [69] coating are effective and unambiguous
strategies to prevent nonspecific adsorption of the desired proteins. Protein-resistant poly-
mers such as PEG that contain ester linkages can be further used as an interface to specif-
ically control the covalent coupling of proteins [209]. For example, specific binding of
streptavidin onto SWNTs has been achieved by functionalization of CNTs with biotin and
oligomeric PEG via ester-to-amide transformation reactions [68].
12.4.2
Biofunctionalization of Nanowires
In addition to CNTs, 1D nanostructures such as magnetic NWs [210,211], semiconductor
[62,212,213], and conducting-polymer NWs [214] offer the prospect of high sensitivity and
 
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