Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker

Siva Krishna Mohan Nalluri, Jelle B. Bultema, Egbert J. Boekema, Bart Jan Ravoo

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

This contribution describes the metal ion responsive adhesion of vesicles induced by a conformational switch of a non-covalent linker molecule. A p-tert-butylbenzyl dimer with a flexible N,N[prime or minute]-bis(3-aminopropyl)ethylenediamine spacer was used as a non-covalent linker, which induces aggregation and adhesion (but not fusion) of host bilayer vesicles composed of amphiphilic [small beta]-cyclodextrins by the formation of hydrophobic inclusion complexes. The aggregation and adhesion of the vesicles in dilute aqueous solution was confirmed by isothermal titration calorimetry (ITC), optical density measurements at 600 nm (OD600), dynamic light scattering (DLS), [small zeta]-potential measurements, cryogenic transmission electron microscopy (cryo-TEM) and fluorescence spectroscopy. However, in the presence of a divalent metal ion like Cu2+, the tetra-amine linker molecule forms a stable metal coordination complex and dramatically switches its conformation from linear to bent, which results in the dissociation of intervesicular complexes, and leads to the dispersion of vesicle clusters. This process is reversible in the presence of a strong metal ion chelator, such as EDTA, that scavenges the Cu2+ ion complexed by the linker. The linker molecule regains its linear conformation and triggers the re-aggregation of the vesicles. In contrast, conformational switching was inhibited by introducing a rigid N,N[prime or minute]-bis(3-aminopropyl)piperazine spacer in the non-covalent linker molecule and vesicles do not aggregate in the presence of a cyclic guest that can only bind intravesicularly. Thus, a metal ion regulated molecular switch can control the aggregation state of an organic colloidal solution.
LanguageEnglish
Pages2383-2391
Number of pages9
JournalChemical Science
Volume2
Issue number12
Early online date5 Sep 2011
DOIs
Publication statusPublished - 2011

Fingerprint

Metal ions
Adhesion
Agglomeration
ethylenediamine
Molecules
Switches
Conformations
beta-Cyclodextrins
Regain
Density (optical)
Coordination Complexes
Fluorescence spectroscopy
Calorimetry
Dynamic light scattering
Zeta potential
Chelating Agents
Titration
Edetic Acid
Dimers
Cryogenics

Keywords

  • metal ion
  • responsive adhesion
  • vesicles
  • conformational switching
  • non-covalent linker

Cite this

Mohan Nalluri, S. K., Bultema, J. B., Boekema, E. J., & Ravoo, B. J. (2011). Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker. Chemical Science, 2(12), 2383-2391. https://doi.org/10.1039/C1SC00422K
Mohan Nalluri, Siva Krishna ; Bultema, Jelle B. ; Boekema, Egbert J. ; Ravoo, Bart Jan. / Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker. In: Chemical Science. 2011 ; Vol. 2, No. 12. pp. 2383-2391.
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Mohan Nalluri, SK, Bultema, JB, Boekema, EJ & Ravoo, BJ 2011, 'Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker' Chemical Science, vol. 2, no. 12, pp. 2383-2391. https://doi.org/10.1039/C1SC00422K

Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker. / Mohan Nalluri, Siva Krishna; Bultema, Jelle B.; Boekema, Egbert J.; Ravoo, Bart Jan.

In: Chemical Science, Vol. 2, No. 12, 2011, p. 2383-2391.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Metal ion responsive adhesion of vesicles by conformational switching of a non-covalent linker

AU - Mohan Nalluri, Siva Krishna

AU - Bultema, Jelle B.

AU - Boekema, Egbert J.

AU - Ravoo, Bart Jan

PY - 2011

Y1 - 2011

N2 - This contribution describes the metal ion responsive adhesion of vesicles induced by a conformational switch of a non-covalent linker molecule. A p-tert-butylbenzyl dimer with a flexible N,N[prime or minute]-bis(3-aminopropyl)ethylenediamine spacer was used as a non-covalent linker, which induces aggregation and adhesion (but not fusion) of host bilayer vesicles composed of amphiphilic [small beta]-cyclodextrins by the formation of hydrophobic inclusion complexes. The aggregation and adhesion of the vesicles in dilute aqueous solution was confirmed by isothermal titration calorimetry (ITC), optical density measurements at 600 nm (OD600), dynamic light scattering (DLS), [small zeta]-potential measurements, cryogenic transmission electron microscopy (cryo-TEM) and fluorescence spectroscopy. However, in the presence of a divalent metal ion like Cu2+, the tetra-amine linker molecule forms a stable metal coordination complex and dramatically switches its conformation from linear to bent, which results in the dissociation of intervesicular complexes, and leads to the dispersion of vesicle clusters. This process is reversible in the presence of a strong metal ion chelator, such as EDTA, that scavenges the Cu2+ ion complexed by the linker. The linker molecule regains its linear conformation and triggers the re-aggregation of the vesicles. In contrast, conformational switching was inhibited by introducing a rigid N,N[prime or minute]-bis(3-aminopropyl)piperazine spacer in the non-covalent linker molecule and vesicles do not aggregate in the presence of a cyclic guest that can only bind intravesicularly. Thus, a metal ion regulated molecular switch can control the aggregation state of an organic colloidal solution.

AB - This contribution describes the metal ion responsive adhesion of vesicles induced by a conformational switch of a non-covalent linker molecule. A p-tert-butylbenzyl dimer with a flexible N,N[prime or minute]-bis(3-aminopropyl)ethylenediamine spacer was used as a non-covalent linker, which induces aggregation and adhesion (but not fusion) of host bilayer vesicles composed of amphiphilic [small beta]-cyclodextrins by the formation of hydrophobic inclusion complexes. The aggregation and adhesion of the vesicles in dilute aqueous solution was confirmed by isothermal titration calorimetry (ITC), optical density measurements at 600 nm (OD600), dynamic light scattering (DLS), [small zeta]-potential measurements, cryogenic transmission electron microscopy (cryo-TEM) and fluorescence spectroscopy. However, in the presence of a divalent metal ion like Cu2+, the tetra-amine linker molecule forms a stable metal coordination complex and dramatically switches its conformation from linear to bent, which results in the dissociation of intervesicular complexes, and leads to the dispersion of vesicle clusters. This process is reversible in the presence of a strong metal ion chelator, such as EDTA, that scavenges the Cu2+ ion complexed by the linker. The linker molecule regains its linear conformation and triggers the re-aggregation of the vesicles. In contrast, conformational switching was inhibited by introducing a rigid N,N[prime or minute]-bis(3-aminopropyl)piperazine spacer in the non-covalent linker molecule and vesicles do not aggregate in the presence of a cyclic guest that can only bind intravesicularly. Thus, a metal ion regulated molecular switch can control the aggregation state of an organic colloidal solution.

KW - metal ion

KW - responsive adhesion

KW - vesicles

KW - conformational switching

KW - non-covalent linker

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DO - 10.1039/C1SC00422K

M3 - Article

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SN - 2041-6520

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