Preparation, characterization and antimicrobial activity of 6-amino-6-deoxychitosan

► 6-Amino-6-deoxychitosan was prepared successfully via 6-tosyl-N-phthaloylchitosan. ► It had a wide spectrum of antimicrobial activity and better activity than chitosan. ► It showed antimicrobial activity not only in acidic media but also in basic media. ► The positive charge was not the sole factor resulting in antimicrobial activities.