Cationic polymers made from poly(2 oxazoline)s for biomedical applications The present thesis deals with the convenient modification of cationic polymers based on poly(2 oxazoline)s to enhance their biological properties and introduce targeting sites while maintaining the efficiency for biomedical applications. Besides enhancing the biocompatibility the biodegradability and the transport of genetic material the specific drug targeting using poly(ethylene imine) derivatives is a major challenge. The presented modification approaches enable among others the selective transport of genetic material into a human breast cancer cell line or the successful transport through a highly selective blood brain barrier model. This work will be the basis for further tailor made polymer systems and encourage researchers to continue the investigation of modified cationic polymers. In particular the combination of drug delivery and cell specific targeting is of tremendous interest for the future treatment of human diseases and has to take the next step from bench to bedside.