This invention discloses chemically modified polyaminosaccharides, in particular chemically modified chitosans, in the molecular structure of which a predetermined proportion of the amino functional groups is sulfonated by the hydrocarbyl sultone compound via a covalent bond. Such chemically modified polyaminosaccharides may be produced by a process of sulfonating an un-modified polyaminosaccharide having amino functional groups by a hydrocarbyl sultone compound in the presence of an organic solvent under a suitable temperature. Chemically modified chitosans of this invention may be used in a variety of applications, including wound healing.