Different Molecular Weight Chitosans Prepared via the Ionic Liquid Hydrolysis and their Antibacterial Activity

Abstract

The hydrolysis effect of ionic liquid glycine chloride [Gly]Cl aqueous system without any catalyst on the degradation for chitosan were studied. The molecular weight (Mw) and degree of deacetylation (DD) of degraded products were tested via the viscometric method and the titration method, respectively. The structure of the raw and degraded chitosans were assessed through Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Besides, the antibacterial effects of different Mw chitosans to Escherichia coli and Staphylococcus aureus were evaluated. The results showed that [Gly]Cl aqueous solution was of good assistant degradation effect for chitosan and different molecular weight (300-800 kDa) chitosans were obtained with different processing time via the ionic liquid hydrolysis method. The DD of degraded chitosans tested from titration method was almost unchanged by the treatment. The FTIR and XRD results showed that the ionic liquid degradation had no obvious effect on the molecular structure of chitosan. Besides, the antibacterial activity was closely relevant to the chitosan concentration and Mw. When the concentration was greater than 0.005% (w/v), chitosan began to show strong antibacterial activity. Molecular weight of 636 kDa exhibited commendable antimicrobial properties to E. coli and S. aureus simultaneously.

Chitosans from Rhizopus stolonifer (strain CBMAI 1551): Characterization and Dense Film Formation

“…The spectra for all samples show the typical absorption bands of chitosan: a broad band in the range of 3000 cm -1 to 3700 cm -1 , related to O-H stretching, two bands in the range of 2800 cm -1 to 3000 cm -1 , related to C-H stretching, one at 1663 cm -1 , related to C=O stretching of the amide group (acetylated units), one at 1573 cm -1 , related to N-H bending, one at 1420 cm -1 , related to C-H bending, and a series of other absorption bands below 1500 cm -1 related to other functional groups [16], [21], [24].It can be observed in Fig. 2 that, for CTS1551ss, theabsorbance of the amine group (1573 cm -1 ) is much greater than that of acetylated groups (1663 cm -1 ), indicating a higher deacetylation degree.…”