159
4 Notes
1. This composition is advantageous in comparison to the literature, due to the fact that in all synthetic steps, water is used as
solvent, avoiding the use of organic solvents.
2. Warm to 70 °C for 30 min with vigorous stirring in a nitrogen
flow.
3. Leave the mixture for 30 min.
4. The emulsion is centrifuged by various cycles of resuspension
in water (3 × 8000 rpm (7491 × g) for 5 min).
5. Aqueous solution of HCl, pH = 3.
6. Aqueous solution of NaOH, pH = 10.
7. The resulting emulsion is purified via various resuspension
cycles in water (4 × 10,000 rpm (11704 × g) for 5 min).
8. The intermediate layer is selected to be formed by use of modified cellulose which functions as a cross-linker for stabilization
purposes between the other two layers. This stabilization has
been performed by cross-linking between the modified cellulose and hydroxypropyl cellulose via ester bonds and between
chitosan through amide bond formation.
Table 2
AT-IR characteristic peaks of synthesized multi-sensitive microspheres
Wavenumber (cm
−1
)
Vibration
Synthesis of PMMA@HPC@CS microspheres
3669
C-H bond of hydroxypropyl
cellulose’s propyl group
2980, 2893
Aliphatic bonds C-H
1726 (sharp peak)
-C=O of methyl methacrylate
and succinic acid segment of
modified cellulose
1059
C-O-C pyranose ring (see Note
16)
892
β-Glycosidic bonds between
the structural units of the
cellulose
Synthesis of PMMA@HPC@CS@CH microspheres
1640
N-H bond of chitosan
After cross-linking
1631
-C=O of N-H (see Note 17)
Design of Drug Delivery Systems Based on Polysaccharides