Alkylsulfonated polyaminosaccharides, such as alkylsulfonated chitosan, having a sultone substituent covalently bonded to the amino group and a known size and degree of substitution may be produced by methods of the invention. Such methods may include heating of the polyaminosaccharide in a polar solvent, such as alcohol, ether, or alcoholether to reflux, then adding an alkyl sultone. Alkylsulfonated polyaminosaccharides of the present invention may be used in a wide variety of applications. Alkylsulfonated chitosan is particularly useful in wound healing.