Researches on the Internal Molecular Weight Uniformity of Chitosan Biomaterials

Uniform molecular weight(Mw) chitosan(CS) is highly demanded in medical biomaterial industry. This present article described heterogeneous degradation of CS in aqueous HCl/ethanol solution, in which progress uniform Mw CS was successfully prepared. The Mw distribution of CS was measured by gel permeation chromatography(GPC) analysis. Moreover, the structure and properties of degraded CS were characterized by Fourier transform infrared spectroscopy(FT-IR), nuclear magnetic resonance spectroscopy(1 H NMR), X-ray diffraction(XRD) and thermogravimetric(TG) analysis. In addition, the biocompatibility of degraded CS was also assessed by hemolysis rate(HR) measurement. The Mw of CS dramatically decreased from 246 KDa to 76 k Da at the initial 30 min, and stabilized at 18 kDa after 24 h. GPC analysis results showed that the degraded CS molecular become homogenization. FT-IR and 1 H NMR analysis confirmed the basic structure of CS molecular backbone was not destroyed during this progress. Besides, the water solubility of CS was not significantly influenced by this reaction. Moreover, the XRD analysis revealed that crystallinity of degraded CS increased from 70.32% to 99.25% with time. The TG analysis showed improved thermal stability of degraded CS. HR measurement demonstrated the degraded CS possessed excellent biocompatibility. This simple and efficient heterogeneous degradation would open up a new route to produce uniform Mw CS.