Molecular Recognition‐Mediated Transformation of Single‐Chain Polymer Nanoparticles into Crosslinked Polymer Films

Abstract

We describe single‐chain polymer nanoparticles (SCNPs) possessing intramolecular dynamic covalent crosslinks that can transform into polymer films through a molecular recognition‐mediated crosslinking process. The SCNPs utilise molecular recognition with surface‐immobilised proteins to concentrate upon a substrate, bringing the SCNPs into close spatial proximity with one another and allowing their dynamic covalent crosslinkers to undergo intra‐ to interpolymer chain crosslinking leading to the formation of polymeric film. SCNPs must possess both the capacity for specific molecular recognition and a dynamic nature to their intramolecular crosslinkers to form polymer films, and an investigation of the initial phase of film formation indicates it proceeds from features which form upon the surface then grow predominantly in the xy directions. This approach to polymer film formation presents a potential method to “wrap” surfaces displaying molecular recognition motifs—which could potentially include viral, cellular and bacterial surfaces or artificial surfaces displaying multivalent recognition motifs—within a layer of polymer film.

Exploiting the Structural Metamorphosis of Polymers to ‘Wrap’ Micron‐Sized Spherical Objects

“…We chose to intramolecularly crosslink P1 with dynamic covalent acyl hydrazone bonds, which we have previously [16] shown are able to undergo intra-to interchain crosslinking when concentrated. Thus, treatment of dyn-P1-MAN with succinic dihydrazide (SD) (Figure 3b, step ii) induces [17] component exchange through a transimination-type process, resulting in intra-polymer chain crosslinking to yield the desired polymer 'wrapping agent' dyn-SCNP-MAN. The crosslinking process was monitored (Figure 3c) by GPC analysis of aliquots of reactions which were treated with NaBH 3 CN to reduce the dynamic hydrazone bonds (Figure 3b, step iii); this 'fixing' of all dynamic bonds was required to ensure the species cannot undergo any component exchange process during analysis.…”

“…Comparison of MGV values after treatment with polymers indicate (Figure 5e) that all microparticles are of similar brightness (MGV values ~37-51), except the sample treated with dyn-SCNP-MAN (pink bars), which is considerably brighter (MGV ~116 � 21). Previous work has shown [17] that crosslinked films prepared by molecular recognition-mediated film formation are often thicker than a single layer of polymer chains because the initially formed layer is able to recruit further chains from solution into the crosslinked network. This possibility is not available to the control polymers as they lack dynamic crosslinkers, and hence there is less fluorescence associated with their coated microparticles.…”

Carbohydrate inhibitors of cholera toxin

“…They were able to show that in the presence of LTB, the E. coli homologue of CTB, the polymer self-optimised its binding affinity for the protein by increasing the proportion of galactosyl residues in the backbone. In the presence of low concentrations of a dihydrazide cross-linking agent, these polymers can also be used to make crosslinked films on surfaces coated with bacterial toxin lectins [ 72 ].…”

A ‘catch-and-release’ receptor for the cholera toxin

“…The construction of receptors or inhibitors using polymer-based systems allows for convenient access to the large molecular architectures required to bridge recognition sites on the surfaces of proteins, eliminating the need for the demanding synthesis of complex architectures such as dendrimers. 5 The choice of a synthetic polymer scaffold for the construction of receptors also enables the inclusion of secondary functionality, such as compositional adaptivity, 6,7 or the ability to respond to environmental stimuli such as temperature 8 or pH, 9 to produce an adaptive material.…”