this application discloses compositions of carbohydrate - modified polymers , such as polyethylenimine modified with cyclodextrin moieties , for carrying drugs and other active agents , such as nucleic acids . compositions are also disclosed of carbohydrate - modified polymer carriers that release such agents under controlled conditions . the invention also discloses compositions of carbohydrate - modified polymer carriers that are coupled to biorecognition molecules for targeting the delivery of drugs to their site of action .