DESIGN AND SYNTHESIS OF ENDOSOMOLYTIC CONJUGATED POLYASPARTAMIDE FOR CYTOSOLIC DRUG DELIVERY - Biologically-Responsive Hybrid Biomaterials - page 186

from 1 to 5%. This is due to the reinforced interactions with PCL chains by an
increase in hydrophobicity and crystallinity.
Kim and coworkers also prepared amphiphilic poly(2-
hydroxyethyl)aspartamides (PHEA) by grafting lactic acid oligomers onto
PHEA, which showed the transition from a micelle to vesicle structure with a DS
of the lactic acid and formed nano-sized vesicles, nanosomes. [22] Our research
group developed novel imidazole-containing polyaspartamides by successive
graft reaction of MPEG and API on PSI. [23] Their aggregate size in aqueous
solution decreased from 250 to 130 nm upon increasing the DS of the
hydrophilic MPEG chains from 1.5 to 3.1%, as shown in Figure 7.

350

300

250

200

150

100

50

0

1 2 3

Degree of substitution of MPEG (%)

Fig. 7. Mean particle size of MPEG/API-g-polyaspartamide as a function of degree of substitution
of MPEG.

Fig. 8. SEM image of the C18/MPEG/API-grafted polyaspartamide.