BULK AND SOLUTION PROPERTIES OF PEPTIDE-POLYMER CONJUGATES - Biologically-Responsive Hybrid Biomaterials - page 33

Fig. 13. Schematic diagram of vesicles formed from PLArg 60 - b -PLLys 20 . Adapted from [121].
well-suited for vesicle formation, since the middle block promotes membrane
assembly due to its insolubility but discourages micelle assembly due to its
rigidity. Vesicle size increased considerably with temperature increase due to a
shift in the PLLys from a compact ŋ -helix to an elongated Ȳ -sheet secondary
structure (CD spectroscopy). Light scattering data showed that the
hydrodynamic radius of PLLys 134 -(PBLG-d7) 64 -PLLys 134 vesicles increased from
92.5 nm at 25 °C to 148 nm at 37 °C at pH 11.5. The formation of vesicles from
a solution containing plasmid DNA and copolypeptides was also investigated
with a number of techniques, including AFM, cryo-TEM, and scanning electron
microscopy (SEM). Plasmid DNA was found to be partially encapsulated by the
vesicle and partially condensed on the PLLys phase of the vesicle membrane.
Jing and collaborators [123] reported vesicle formation from simple aqueous
dissolution of a copolypeptide material - poly( L -lysine)- b -poly( L -phenylalanine)
(PLLys- b -PLPhe) (specifically PLLys 53 - b -PLPhe 12 ). Water selectively dissolved
hydrophilic PLLys, while intra-chain hydrogen bonding and hydrophobic
interactions of the PLPhe phase drove subsequent vesicle assembly. Increasing