Self‐Assembly and Responsive Behavior of Poly(peptide)‐Based Copolymers

Abstract

Well‐defined copolymers synthesized by combining poly(ethylene glycol) (PEG) and amino acid based building blocks are investigated with regard to their helical rigidity and self‐assembly. Optical active block copolymers reported here are designed to have a pendant amino acid and polymerizable group, that is, isonitrile in order to induce helix formation and reduce the mobility of polymer chains by forming a hydrogen bond network so that a helix with reasonable rigidity can be obtained. Due to the amphiphilicity and a relatively shorter PEG as a coil, these polymers form micelles as observed under transmission electron microscopy in which copolymers PEG108‐b‐PPIC764 and PEG108‐b‐PPIC1020 appear to be evolving into nanoparticles with a size distribution of 100–200 nm. Circular dichroism spectroscopy is employed to study the nature of the helix and its rigidity. The folding and unfolding of polymer helix as a result of the ability of a selective solvent to form/disrupt hydrogen bonds with the peptide linkage is also discussed to highlight the responsive nature of the polymer.

Chirality in peptide‐based materials: From chirality effects to potential applications

“…Kumar and coworkers synthesized a solvent-responsive poly(peptide)-based copolymer composed of a hydrophilic PEG as coil part and a hydrophobic L-valine derivative as rigid pendant covalently bonded on poly(phenyl isocyanide) (PPI). 57 These polymers could self-assemble into a worm-like micelle, of which the flexible PEG blocks exposed outside the chamber and PPI stayed inside. The ratio of PEG and chiral poly(phenyl isocyanide) units could regulate the length of hydrophilic-hydrophobic segment and further change the rigidity of the chiral helix.…”

“…These disk‐shaped polymers can form a series of columnar stacks bearing modifiable moieties featured with specific stereochemical properties. Kumar and coworkers synthesized a solvent‐responsive poly(peptide)‐based copolymer composed of a hydrophilic PEG as coil part and a hydrophobic l ‐valine derivative as rigid pendant covalently bonded on poly(phenyl isocyanide) (PPI) 57 . These polymers could self‐assemble into a worm‐like micelle, of which the flexible PEG blocks exposed outside the chamber and PPI stayed inside.…”

Simultaneous Passivation and Encapsulation of Black Phosphorus Nanosheets (Phosphorene) by Optically Active Polypeptide Micelles for Biosensors

“…Poly(phenyl isocyanidepeptide)s, a new class of polymers, are known for undergoing self-assembly via noncovalent interactions and dynamic changes along the backbone leading to a helical confirmation. 20,21 In these polymers, folding and unfolding of helix under certain circumstances can be tuned by introducing an active chemical functionality, which in turn can offer multiple purposes such as for memory device, sensor, and drug delivery. Additionally, it has been found to be nontoxic to the tissue.…”

“…Additionally, it has been found to be nontoxic to the tissue. 20,21 For obtaining a copolymer, the hydrophilic segment, for instance, PEG has been also linked covalently to the poly(phenyl isocyanidepeptide) chain in which self-assembly and responsive nature of the corresponding copolymer was achieved in aqueous phase. 21−23 These copolymers have been reported to show formation of micelles, vesicles, and other nanostructures depending on the fraction of polar and nonpolar segment.…”

“…Herein, for the first time, we demonstrate a simple and yet useful strategy to have combined the illusive properties of 2D nanosheets of phosphorene and an artificial helical copolymer engineered chemically for its architecture and supramolecular assembly as reported previously by our group. 21 The helical polymer provides multifold benefits: (1) it passivates and encapsulates BP nanosheets, (2) it electronically interacts with the BP nanosheets, and (3) it can allow fabrication of inorganic BP nanosheets for their integration in devices without sacrificing the inherent properties of BP nanosheets, (4) it protects BP nanosheets from atmospheric oxygen. The major highlight of this research includes the noncovalent passivation and encapsulation of BP nanosheets within the optically active micelles or nanopockets composed of helical chains and thereby creating a shell or coating around the nanosheets while a signal can still be generated via electron transfer (ET).…”