Chemical Feedback in Templated Reaction-Assembly Networks

Abstract

Chemical feedback between building block synthesis and their subsequent supramolecular self-assembly into nanostructures has profound effects on assembly pathways. Nature harnesses feedback in reaction-assembly networks in a variety of scenarios including virion formation and protein folding. Also in nanomaterial synthesis, reaction-assembly networks have emerged as a promising control strategy to regulate assembly processes. Yet, how chemical feedback affects the fundamental pathways of structure formation remains unclear. Here, we unravel the pathways of a templated reaction-assembly network that couples a covalent polymerization to an electrostatic coassembly process. We show how the supramolecular staging of building blocks at a macromolecular template can accelerate the polymerization reaction and prevent the formation of kinetically trapped structures inherent to the process in the absence of feedback. Finally, we establish a predictive kinetic reaction model that quantitatively describes the pathways underlying these reaction-assembly networks. Our results shed light on the fundamental mechanisms by which chemical feedback can steer self-assembly reactions and can be used to rationally design new nanostructures.

FRET-Based Determination of the Exchange Dynamics of Complex Coacervate Core Micelles

“…Also, in our case, polydispersity probably has played a role, as the donor and acceptor polymer have a dispersity of 1.7 and 1.6, respectively. This is high for polymers synthesized by RAFT polymerization and is probably caused by the fact that the polymerization of SPMA can be prone to termination reactions as we have observed earlier by following the reaction with 1 H NMR spectroscopy . To further discuss the effect that this large polydispersity might have on the exchange, we first need to know more about the exchange mechanisms.…”

“…This is high for polymers synthesized by RAFT polymerization and is probably caused by the fact that the polymerization of SPMA can be prone to termination reactions as we have observed earlier by following the reaction with 1 H NMR spectroscopy. 14 To further discuss the effect that this large polydispersity might have on the exchange, we first need to know more about the exchange mechanisms. Therefore, we will first focus on these mechanisms and come back to the polydispersity effect later in this paper.…”

“…The synthesis of the unlabeled PSPMA homopolymers is described elsewhere. 14 The number average molecular weights (M n ) and weight average molecular weights (M w ) of the PSPMA polymers were determined using an Agilent aqueous gel permeation chromatography (GPC) equipped with a refractive index detector and using PL aquagel Mixed-M as the column. NaNO 3 (0.2 M)−NaH 2 PO 4 (0.01 M) buffer solution (pH = 7.0) with NaN 3 (0.2 wt %) was used as the eluent at a flow rate of 0.6 mL min −1 at 30 °C.…”

“…After all, the exchange dynamics determines the rate at which the cargo is exposed to the surroundings and thus the level of protection that the C3M gives. Furthermore, in some cases, the final structure of the C3Ms is governed by their preparation pathways. − This demonstrates that kinetic effects can determine the C3M properties and thus their encapsulation efficiency.…”

Switchable Electrostatically Templated Polymerization

“…In these socalled polymerization-induced electrostatic self-assembly (PIESA) or electrostatic assembly-directed polymerization (EADP) procedures, neutral-polyelectrolyte block copolymers are being synthesized in the presence of oppositely charged templates. [13][14][15][16][17][18] At a certain block length, the charged components phase separate and become strongly enriched in a condensed state. The neutral block restricts the phase separation to nanoscopic length scales, generating micelles, vesicles and other nanoparticles.…”