Sticky Supramolecular Grafts Stretch Single Polymer Chains

Abstract

The folding of single polymeric chains into single chain polymeric nanoparticles (SCPNs) is a unique strategy to prepare ordered structures at the nanoscopic level. Structure forming elements are attached to a polymer chain designed to fold it into a well-defined object, the SCPN. The self-assembly of these units has been investigated in great detail. However, little is known about the impact of the resulting secondary structure on the conformation of the polymer chain. Here we employ a combination of scattering methods and spectroscopy to study how pendant chiral benzene-1,3,5-tricarboxamides (BTAs) fold oligo(ethylene glycol) methyl ether methacrylate-based polymers into SCPNs. Circular dichroism spectroscopy shows that the extent of BTA self-assembly on the polymer chain in water can be fine-tuned by means of temperature and cosolvent addition (isopropanol). Small-angle neutron scattering experiments demonstrate that single polymer chains have an asymmetric shape with a constant cross section, R cs, and variable length, L, with L > R cs. The polymer chain extends and shortens in response to variations in temperature and solvent composition, which also influence the self-assembly of the BTA units. The SCPNs stretch upon association and shrink upon disassociation of the grafted supramolecular moieties.

Understanding the catalytic activity of single‐chain polymeric nanoparticles in water

“…Supramolecular folding of polymer chains into single chain polymeric nanoparticles (SCPNs) is an attractive alternative to prepare compartmentalized, water-soluble, nanometersized particles with a hydrophobic interior. [29][30][31][32] Notably, the benzene-1,3,5-tricarboxamide (BTA) is an attractive unit to form SCPNs with well-defined, conformationally adaptable, three-dimensional structures as a result of the hydrogenbond-driven, helical self-assembly of the BTA units. 31 Detailed scattering studies revealed that water-soluble copolymers based on oligo(ethylene glycol) methacrylate (oEGMA) and benzene-1,3,5-tricarboxamide methacrylate (BTAMA) fold in water into compact conformations Additional Supporting Information may be found in the online version of this article.…”

“…consisting of a single polymer chain, and having a slightly elongated shape as a result of the BTA self-assembly. 29 We recently inserted catalytically active moieties into BTAbased amphiphilic copolymers. 31,33 A set of random amphiphilic copolymers comprising oEGMA/BTAMA and L-proline units was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization.…”

Characterization of single-chain polymer folding using size exclusion chromatography with multiple modes of detection

“…Meijer and coworkers also expanded the scope of possible architectures by successfully synthesizing SCNP from cylindrical brush block polymers as well as an orthogonally collapsible ABA triblock copolymer [6,22]. Additionally, this group studied temperature and co-solvent induced changes in the secondary structures of benzene-1,3,5-tricarboxamides (BTA)-based SCNPs, and developed a compartmentalized metal ion SCNP sensor that shows impressive binding affinities [4,23]. The Barner-Kowollik group demonstrated a photo-induced Diels-Alder ligation to create SCNP in addition to using metal-ligand complexation to induce controlled folding by linking chain ends [1,24].…”

Endowing Single-Chain Polymer Nanoparticles with Enzyme-Mimetic Activity

“…[1][2][3][4][5][6] SCNPs based on self-collapsed individual chains mimic the structure of folded biomacromolecules although in a rough, primitive manner. [7][8][9][10][11][12][13][14] Recently, we have demonstrated a very efficient strategy for the construction of transient binding disordered protein-mimic nano-objects based on SCNPs. 15 Small angle neutron scattering (SANS) and molecular dynamics (MD) simulation results undoubtedly showed that the form factor of these SCNPs in solution resembles that of intrinsically disordered proteins (IDPs).…”