Finally, the products were exhaustively dialyzed (MWCO
14,000) against DMF and deionized water, and then lyophilized
to obtain the white, cotton wool-like products. Mel-OCM-chitosan
conjugates without amino acid spacer was synthesized with
the same method. The products were synthesized and named
in Table 1
2.3. Instrumental analyses
FT-IR spectrum analysis: Samples were prepared as KBr pellet
and scanned against a blank KBr pellet background at range of
600–4000 cm−1 and characterized by FT-IR spectrometer (Bruker
Tesor 27, Germany).
1H NMR spectroscopy analyses: The 1H NMR spectrums were
determined on a Varian 600 spectrometer (Varian, USA) using
tetramethylsilane as internal standard at 25 ◦C. The samples
of Fmoc-Mel, Fmoc-Mel-Gly, Fmoc-Mel-Phe, Fmoc-Mel-Leu, and
Fmoc-Mel-Pro were dissolved in CDCl3, while OCM-chitosan and
Mel-OCM-chitosan conjugates were dissolved in D2O.