Structure of Polypeptide-Based Diblock Copolymers in Solution:  Stimuli-Responsive Vesicles and Micelles

Abstract

Polypeptide-based diblock copolymers forming either well-defined self-assembled micelles or vesicles after direct dissolution in water or in dichloromethane, have been studied combining light and neutron scattering with electron microscopy experiments. The size of these structures could be reversibly manipulated as a function of environmental changes such as pH and ionic strength in water. Compared to other pH-responsive seldassembled systems based on "classical" polyelectrolytes, these polypeptide-based nanostructures present the ability to give a response in highly salted media as the chain conformational ordering can be controlled. This makes these micelles and vesicles suitable for biological applications: they provide significant advantages in the control of the structure and function of supramolecular self-assemblies.

Self‐assembly and responsiveness of polypeptide‐based block copolymers: How “Smart” behavior and topological complexity yield unique assembly in aqueous media

“…8 nm through the helix-coil transition; they mention that this smaller size change could be a result of folding or disruption of the PLGA helices. 59 Schlaad and coworkers reported large vesicle formation for PB 165 -b-PLys 88 under physiological saline conditions. 71 They reported a change in average radius from 364 nm at pH 7.0 ( 100% protonation) to 215 nm at pH 10.3 ( 35% protonation).…”

“…[55][56][57] Assemblies with Polypeptide Coronas The past two decades have seen several literature reports of aqueous assembly of block copolymers with peptide corona chains, whereby responsiveness is governed in part by changes in the secondary structure. 11,42,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] Much of this research focus has been devoted to pH-responsive block copolymers containing peptides such as poly(L-lysine) (PLys) (pKa 10.3) 73 and poly(L-glutamic acid) (PLGA) (pKa 4.3) 70 which exhibit helix-coil transitions associated with the charged state of the amino or carboxylic acid side chains of PLys and PGlu respectively.…”

“…98,99 A 2 B star copolymers have been synthesized containing two hydrophilic peptide blocks attached to a hydrophobic polymer. 59,101 Both of these reports took advantage of controlled radical techniques to create synthetic polymers that could be efficiently used to couple to synthesized polypeptide blocks or used as macroinitiators for ROP of the NCA. For example, Lecommandoux and coworkers modified a bromine-terminated PS with a trifunctional amine to afford PS-(NH 2 ) 2 .…”

“…98,99,118 Polypeptide-Based A 2 B Star Copolymers There have been a few recent reports on the aqueous self-assembly of peptide-based A 2 B star copolymers, with two hydrophilic peptide chains attached to a hydrophobic B block. 59,119 Ding and coworkers studied poly(N-isopropyl acrylamide)-b-(PLys) 2 (PNIPAM-b-(PLys) 2 ),coupled through azide-alkyne chemistry. 59 Above the LCST of PNIPAM (ca.…”

Thermotropic Ionic Liquid Crystals via Self-Assembly of Cationic Hyperbranched Polypeptides and Anionic Surfactants

“…Furthermore, in contrast to peptidic polymers covalently modified with mesogenic units, 26,27 polypeptide-surfactant complexes are expected to be pH responsive and thus offer a very promising pathway to design pH-responsive mesostructures. 28 In such an approach, the exact liquid crystalline phase designed using supramolecular assemblies of polypeptides and lipids can in principle be controlled by a large number of factors such as the structure of the lipid, the architecture of the polypeptide, and the pH.…”