Single‐Chain Folding of Synthetic Polymers: A Critical Update

Abstract

The current contribution serves as a critical update to a previous feature article from us (Macromol. Rapid Commun. 2012, 33, 958−971), and highlights the latest advances in the preparation of single chain polymeric nanoparticles and initial—yet promising—attempts towards mimicking the structure of natural biomacromolecules via single‐chain folding of well‐defined linear polymers via so‐called single chain selective point folding and repeat unit folding. The contribution covers selected examples from the literature published up to ca. September 2015. Our aim is not to provide an exhaustive review but rather highlight a selection of new and exciting examples for single‐chain folding based on advanced macromolecular precision chemistry. Initially, the discussion focuses on the synthesis and characterization of single‐chain folded structures via selective point folding. The second part of the feature article addresses the folding of well‐defined single‐chain polymers by means of repeat unit folding. The current state of the art in the field of single‐chain folding indicates that repeat unit folding‐driven nanoparticle preparation is well‐advanced, while initial encouraging steps towards building selective point folding systems have been taken. In addition, a summary of the—in our view—open key questions is provided that may guide future biomimetic design efforts.

Synthesis of Sequence-Controlled Multiblock Single Chain Nanoparticles by a Stepwise Folding–Chain Extension–Folding Process

“…[5][6][7] Inspired by this model of biopolymers, folding a single linear polymer chain into a single chain nanoparticle (SCNP) has been recognized as a robust strategy for the construction of biopolymeric nanoparticles with potential applications in catalysis, sensing or biotechnology. [8][9][10][11][12][13][14] Although the design and synthesis of single chain objects has recently received great attention, 15 the development in this field is still in its initial phase. So far, several types of strategies to mediate the single chain collapse to form SCNPs have been explored, [16][17][18][19][20][21][22] ranging from hydrogen bonding, 23-27, 10, 28-31 covalent bonding, [32][33][34][35][36] to dynamic covalent bonding.…”

Synthesis and functionalization of dextran-based single-chain nanoparticles in aqueous media

“…Consequently, SCPNs have gained interest as potential mimetics of biomacromolecules such as proteins 5,6 and for application in different fields including nanomedicine.…”

“…[2][3][4] SCPNs based on synthetic polymers benefit from the possibility of a controlled construction of the precursors in order to prepare tuned SCPNs with desired size and functionality.3 Additionally, a wide variety of biocompatible, non-toxic and ready-to-use natural polymers are available. Consequently, SCPNs have gained interest as potential mimetics of biomacromolecules such as proteins 5,6 and for application in different fields including nanomedicine. [7][8][9] Among natural polymers, polysaccharides can be envisaged as natural analogues of polyethylene glycol (PEG).…”

Tunable slow dynamics in a new class of soft colloids

“…Among the various techniques employed to these ends, the collapse of single polymer chains (precursors) via purely intramolecular cross-linking, into single-chain nanoparticles (SCNPs), has gained increasing interest over recent years [2][3][4][5] . Significant effort is being devoted to endow SCNPs with useful functions for multiple applications in, e.g., nanomedicine, biosensing, bioimaging or catalysis [6][7][8][9][10] .…”