Water-soluble chitotriazolans derived from cationic, neutral, and anionic common chitosan derivatives: Synthesis, characterization, and antibacterial activity

Partially substituted N,N,N-trimethyl chitosan (TMC), N-(2-(N,N,N-trimethylammoniumyl))acetyl chitosan (TAC), 2-hydroxy-3-(N,N,N-trimethylammoniumyl)propyl chitosan (HTC), N-(2-hydroxy)propyl chitosan (HPC), and N-carboxymethyl chitosan (CMC) were reacted with the diazo transfer reagent, imidazole-1-sulfonyl azide, to convert the 2-amino groups to azides. Subsequent reaction via copper-catalyzed azide-alkyne cycloaddition (CuAAC) with N-propargyl-N,N,N-trimethylammonium bromide provided water-soluble "mixed" chitotriazolan derivatives. The NMR data was generally consistent with the complete conversion of all primary amines in the polymer to triazole moieties, except in the case of TAC, where the conversion was similar to 50 %. The mixed chitotriazolans derived from cationic TMC, TAC, and HTC and neutral HPC were active against Gram-positive S. aureus and E. faecalis and Gram-negative bacteria E. coli and P. aeruginosa, but chitotriazolans derived from anionic CMC were inactive.