Steric Constraints Induced Frustrated Growth of Supramolecular Nanorods in Water

Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Appel, R., Fuchs, J., Tyrrell, S. M., Korevaar, P. A., Stuart, M. C. A., Voets, I. K., ... Besenius, P. (2015). Steric constraints induced frustrated growth of supramolecular nanorods in water. Chemistry -A European Journal, 21(52), 19257-19264. DOI: 10.1002/chem.201503616 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Ilja K. Voets, [d, f] Monika Schçnhoff, [c] and Pol Besenius* [a, b] Abstract: Au nique example of supramolecular polymerisation in waterb ased on monomers with nanomolara ffinities, which yield rod-like materials with extraordinarily high thermodynamic stability, yet of finite length, is reported. A small libraryo fc harge-neutral dendritic peptide amphiphiles was prepared,w ith ab ranched nonaphenylalanine-based core that was conjugated to hydrophilic dendrons of variable steric demand. Below ac ritical size of the dendron,the monomers assemble into nanorod-like polymers,w hereas for larger dendritic side chainsf rustratedg rowth into near isotropic particles is observed.T he supramolecular morphologies observed by electron microscopy,X -ray scattering and diffusion NMR spectroscopy studies are in agreement with the mechanistic insights obtained from fitting polymerisationp rofiles:n on-cooperative isodesmic growth leads to degrees of polymerisation that matcht he experimentally determined nanorod contour lengths of close to 70 nm. The reportedd esignsf or aqueous self-assembly into well-defined anisotropic particles has promising potentialf or biomedical applicat...

Tuning the pH‐Switch of Supramolecular Polymer Carriers for siRNA to Physiologically Relevant pH

“…This is a good indication that the neutral Phe‐His‐Phe‐His‐Phe based oligopeptide induces the self‐assembly into ordered supramolecular structures, whereas protonation at a pH close to the p K a value of the isolated histidine amino acid side group of 6.0, leads to the disassembly due to Coulomb repulsion between the assembled aromatic oligopeptide backbone. In the past, we have been able to use CD spectroscopy in combination with cryogenic transmission electron microscopy (cryo‐TEM), small angle X‐ray scattering (SAXS), and diffusion‐based PFG‐NMR experiments, to correlate spectroscopic changes with a supramolecular monomer to polymer transition . The small difference in the pH‐induced transition of 1 compared to 2 of 0.7 pH units, is an indication that the high surface charge density of cationic 2 leads to a slightly less stable polymer and hence more favorable disassembly at lower H + concentrations.…”

“…These combine high robustness and fidelity in the self‐assembly with stimuli‐responsive properties toward pH‐values of the surrounding medium. We have previously reported C 3 ‐symmetrical nonaphenylalanine supramolecular building monomers equipped with dendritic tetraethylene glycol chains, with binding affinities of up to 7 × 10 7 m −1 in water . In order to introduce pH‐switchable properties into the supramolecular polymerization, we changed the peripheral dendritic tetraethylene glycol chains for dendritic carboxylic acids in the amphiphilic monomers that are highly charged and thus molecularly dissolved at neutral pH and self‐assemble into anisotropic supramolecular polymers by acidifying the aqueous medium .…”

Tuneable Transient Thermogels Mediated by a pH‐ and Redox‐Regulated Supramolecular Polymerization

“…This highlights the high robustness of the oxidation damage repair and substrate promiscuity of this class of reductases. [12,18] We further relied on their steric demand and high chain flexibility to introduce repulsive forces in the supramolecular polymerization process,which prevents the formation of infinitely long polymers,aprocess we usually refer to as frustrated growth. [12,18] We further relied on their steric demand and high chain flexibility to introduce repulsive forces in the supramolecular polymerization process,which prevents the formation of infinitely long polymers,aprocess we usually refer to as frustrated growth.…”

Controlling supramolecular polymerization through multicomponent self‐assembly

“…[324][325][326][327][328] Importantly, repulsive contributions in supramolecular systems and polymers can also be based on steric constraints, as reported by Stupp, 329 Lee, 330 Hedrick, 331 Fernandez, Schacher, 332 and Besenius. 333 The lack of charges in hydrophilic dendritic oligoethylene glycol end groups for example simplified mechanistic investigations and thermodynamic characterization of the supramolecular polymers in water. In phenylalanine-rich monomers, the concentration-dependent degree of polymerization and contour length of the nanorod-like polymers was determined from SAXS, PFG-NMR and cryo-TEM experiments and could be correlated with the binding affinities of up to 7 3 10 7 M 21 in phosphate buffer, which were determined using titration experiments.…”

“…In phenylalanine-rich monomers, the concentration-dependent degree of polymerization and contour length of the nanorod-like polymers was determined from SAXS, PFG-NMR and cryo-TEM experiments and could be correlated with the binding affinities of up to 7 3 10 7 M 21 in phosphate buffer, which were determined using titration experiments. 333 More recently, the Besenius group has shown that by using a very hydrophobic hexapeptide, based on phenylalanine alternated with a charged amino acid, in the side arms of either of the comonomers which were further equipped with dendritic tetra(ethylene glycol) chains, a pH-regulated selectivity in the formation of a heterocopolymer and the acidic or basic homopolymer was achieved (Fig. 24).…”