Introduction to Nanotechnology

BiodegradaWe surface 4
Functional group:
Acetal
double bond
c: j +,
Micelle foormatlon
Functionnliration of
polytacwh surface
-t
Dialysis
in water
11.5. SUPRAMOLECULAR STRUCTURES 307
lnleraction with
Ligand rnokcules:
sugar and allgopeptide
PEG laver inhibits non-soecrfic
adsorpiion of protelns '
Hydrophilic segment
r .L.
Surface I, - -
modification Cork-po l yrnerized micelle
with aldehyde groups
on Ihe surface
Figure 11.24. Schematic representation of an aggregation of polylactide (PlA)/polyelhylene-
glycol (PEG) block copolymers (center of fgure). The upper illustration shows how Ihese
copolymers have tormed a PEG layer that inhibits the nonspecific adsorption of proteins. The
lower illustration shows how these copolymers form micelles thal coat a surface. [From Otsuka
et al. (2001).]
polyethylene glycol (PEG) segment on the surface. When the acetal surface was
?mated with TEMPO prior to replacing acetal groups with aldehydes, Fig. 11.2%
indicates that only a vcp weak EPR triplet spectrum was obcrved, probably due to
the direct physical adsorption of TEMPO molecules on tlic surface. Figure 11.25~
shows that RO EPR spin-labcl signal appears when the aldchydc surtice was treated
with a variety of TEMPO lhnt lacked an amino ( -NH2) gmup. The upper part of the
figure shows how the TEMPO molecule bonds to the aldehydc (-CHO) group
located at the end of tlic ctliylene glycol copolymer segment.