Self-assembled nanostructures from peptide–synthetic hybrid block copolymers: Complex, stimuli-responsive rod–coil architectures

Abstract

The synthesis, solution and solid state self-assembly properties of a series of polyisoprene-b-poly(epsilon-benzyloxycarbonyl-L-lysine) PI-b-PZLys and polyisoprene-b-poly(L-lysine) PI-b-PLys block copolymers have been examined. The formation of stimuli-responsive micelles in water has been studied as a function of pH and ionic strength using static and dynamic light scattering, UV-circular dichroism and transmission electron microscopy. The observed change in the micelles dimensions has been directly attributed to the conformational transition in the secondary structure of polypeptide chains. In bulk, these rod-coil copolymers form self-assembled structures that have been characterized using DSC, DMA, WAXS and SAXS techniques. Hexagonal in lamellar (HL) and more interestingly hexagonal in hexagonal (HH) morphologies have been evidenced as a function of the chemical composition.

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

“…Similarly, Lecomandoux and coworkers reported spherical micelles from poly(isoprene) 49 -b-PLys 123 which showed a size change from 23 nm to 44 nm from pH 11 to 6 in a saline solution. 65 Interestingly, they also reported a similar system of poly(butadiene) 48 -b-poly (LGA) 114 (PB-b-PLGA), that resulted in spherical micelle formation that only showed a size change of ca. 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.…”

“…Liu and coworkers also reported schizophrenic assembly behavior of a dual responsive diblock copolymer, poly(N-isopropyl acrylamide) 65 -b-poly(LGA) 110 (PNIPAM 65 -b-PLGA 110 ). 76 At pH below 4 and at 25 C, they report spherical micelles formation with PNIPAM as the corona and the hydrophobic PLGA as the core.…”

“…[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.…”

Role of secondary structure changes on the morphology of polypeptide-based block copolymer vesicles

“…pendently studied a number of synthetic polymer-polypeptide block copolymers with varying hydrophobic blocks as well as varying the amino acids in the polypeptide blocks [11,17,[20][21][22][23][24][25][26]. These studies resulted in a number of pH-responsive micelles and vesicles whereby the responsiveness is due in part to the helix-coil secondary structure transition within the peptide chain.…”

Organometallic–Polypeptide Block Copolymers: Synthesis and Self‐Assembly of Poly(ferrocenyldimethylsilane)‐b‐Poly(ε‐benzyloxycarbonyl‐L‐Lysine)

“…Babin et al observed that the a-helix to b-sheet transition temperature for PZLys blocks in polyisoprene-b-PZLys block copolymers increases with increasing the degree of polymerization (DP) of PZLys blocks. [18] The transition temperature for a PZLys block with a DP n of 75 is % 155 8C, [18] which is close to the temperature (160 8C) at which we annealed our PFS-bPZLys block copolymer samples. Therefore, our study was focused on block copolymer PFS-b-PZLys 2, in which the DP n of PZLys block is 180, corresponding to a transition temperature higher than 200 8C.…”