Poly(ε-N-methacryloyl-L-lysine) (PMALys) was synthesized by free radical polymerization yielding a zwitterionic polymer with M w = 721 000 g mol −1 . The polymer dissolves in pure water as well as in aqueous salt solution up to 5 M NaClO 4 and over wide range of pH values (1.3 ≤ pH ≤ 12.7) as single chains without any sign for aggregate formation. The zwitterionic polymer shows an expanded random coil structure at and close to isoelectric conditions and further expands upon addition of acid and base, respectively. The polymer fulfills four major prerequisites for a promising nano carrier in potential biomedical applications: (1) It is biocompatible, indicated by a low cytotoxicity. (2) It does not aggregate in concentrated human blood serum solution. (3) The amino groups in the polyzwitterion may be utilized for conjugations as demonstrated by labeling reactions with AlexaFluor488. (4) Cell uptake experiments revealed little uptake in bone marrow dendritic cells, i.e., little unspecif ic uptake, which is mandatory for a successful specific targeting of cells. Finally, upon addition of Zn 2+ ions the polyzwitterions may be converted into polycations which are demonstrated to form complexes with DNA. Such complexes may be advantageous for application in gene transfection studies.

Monodisperse high molar mass elastin-like polypeptide macromonomers comprising 20 pentasequences (M = 8332 g/mol) were radically polymerized to high degrees of polymerization P w = 590. Polymerization was conducted in water well above the lower phase transition temperature, i.e., in the phase separated regime. The resulting polymers adopt a cylindrical shape as demonstrated by AFM pictures of solutions spin-cast on mica. The directional persistence of the cylindrical brushes was determined by static light scattering to Kuhn statistical segments lengths l k = 120 nm at 5 mM aqueous NaCl solution which decreased to l k = 54 nm at 0.65 M NaCl. Upon polymerization the phase transition temperature drops significantly and the transition interval becomes sharper. The change of the hydrodynamic radius of the cylindrical brushes was monitored by dynamic light scattering as a function of temperature and revealed a continuous decrease from 20 to 36 °C, above of which aggregates of several hundred nm in size start to form prior to phase separation.