Characterization and bioactivity of self-assembled anti-angiogenic chondroitin sulfate-ES2-AF nanoparticle conjugate

Xing, Liang; Sun, Feng; Wang, Zhendong; Li, Yan; Yang, Zhifang; Wang, Fengshan; Zhai, Guangxi; Tan, Haining

The polypeptide ES2-AF, which was synthesized by solidphase peptide synthesis, was analyzed by high-performance liquid chromatography. The purity of polypeptide ES2-AF was 95.41% and the retention time was 7.750 min. The molecular weight of polypeptide ES2-AF, measured by mass spectrometry (MS), was 2,198.12. To improve the solubility of CS in organic solvents, CS was modified using TBA-OH to form the DMSO-soluble conjugate CS-TBA. 10, 17 The yield of CS-TBA was 89.7%. The 1 H-NMR spectrum of CS-TBA shown in Figure 1C , compared with the 1 H-NMR spectra of CS ( Figure 1B) , shows four signal peaks with chemical shifts of δ=0.97 ppm, 1.40 ppm, 1.68 ppm, and 3.20 ppm, which are characteristic peaks of the butyl group on the reactant TBA-OH. The signal peak in the range δ=1.85-1.95 ppm corresponds to the characteristic methyl group peak of the acetylamino group on CS. The 1 H-NMR spectra of the products showed that the conjugate CS-TBA was successfully prepared by ion exchange and it had good solubility in DMSO.