The present invention relates to graft copolymers of polyvinyl sulfonic-co-vinyl alcohol)-g-poly(lactide-co-glycolide) (P(VS-VA)-g-PLGA) with negatively charged electrolyte properties, their method of preparation and their use. These negatively charged graft copolymers are suitable for effective loading and sustained-release of especially positively charged drugs, proteins and peptides, and drug-loaded particles from these grafted co-polymers are especially useful as parenteral or mucosal drug delivery systems for pharmaceutical applications.
