Preparation, characterization and antibacterial activity of a novel soluble polymer derived from xanthone and O-carboxymethyl-N, N, N-trimethyl chitosan.

In this contribution, a novel soluble and antibacterial polymer, O-xanthonyl-chitosan (CTMC-Xan), was synthesized successfully by grafting 1,3-dihydroxy-xanthone (Xan) to the side chains of O-carboxymethyl-N, N, N-trimethyl chitosan (CTMC). The chemical structure and physical properties of the polymer were analyzed by ¹ H NMR, FT-IR spectra, UV spectra and XRD. The results showed that Xan could covalently bond with the carboxyl groups of CTMC by esterification at a grafting ratio of 9.1%. XRD patterns indicated that CTMC-Xan does not exhibit crystallization. The solubility tests showed that CTMC-Xan was completely dissolved and stable in neutral solution but unstable in acid or basic conditions. Moreover, it was found that the antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of CTMC-Xan was much stronger than that of Xan and CTMC, and the minimal bactericidal concentration (MBC) was 125 μg·mL ^-1 . Due to the enhanced solubility and antibacterial activity, CTMC-Xan could potentially serve as a desirable biomaterial for food and pharmaceutical applications.
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