Paramagnetic self‐assembled nanoparticles as supramolecular MRI contrast agents

Besenius, Pol; Heynens, Joeri; Straathof, Roel; Nieuwenhuizen, Marko M. L.; Bomans, Paul H. H.; Terreno, Enzo; Aime, Silvio; Strijkers, Gustav J.; Nicolay, Klaas; Meijer, E. W.

doi:10.1002/cmmi.498

Cited by 60 publications

(66 citation statements)

References 42 publications

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“…[8] Detailed studies of their aggregation process have highlighted the cooperative nature of these self-assemblies. [9,10] Derivatives of BTA have been investigated as MRI contrast agents, [11] metal complexation agents [12] and utilized in drug-delivery systems. [13] Investigations of BTA-based self-assemblies have focused on the effects of the aliphatic chains, [14,15] introduction of elements of chirality [16] and substitutions on the central aromatic moiety.…”

Section: Introductionmentioning

confidence: 99%

Columnar self-assembly of N,N′,N′′-trihexylbenzene-1,3,5-tricarboxamides investigated by means of NMR spectroscopy and computational methods in solution and the solid state

Banach

Invernizzi

Baudin

et al. 2017

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

Columnar self-assembly of N,N′,N′′-trihexylbenzene-1,3,5-tricarboxamides investigated by means of NMR spectroscopy and computational methods in solution and the solid state

Banach

Invernizzi

Baudin

et al. 2017

Phys. Chem. Chem. Phys.

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“…15 Hence, the details of their self-assembling behavior and their stability in different conditions are of critical importance. The combination of spectroscopic (CD and NMR), scattering (SAXS) and microscopy (cryo-TEM) techniques allows visualization of the formed structures and the quantification of their thermodynamic parameters.…”

Section: Discussionmentioning

confidence: 99%

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

Besenius

Feijter

Sommerdijk

et al. 2012

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For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult 1 . At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates 2,3 , end cappers 4 or selective solvent techniques 5 . Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects 6,7 . Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer ( Scheme 1 ). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by π-π stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1 H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length > 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

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“…[6][7][8][9] Some examples of supramolecular polymers include materials based on discotic benzene tricarboxamides, 10 porphyrins, 11 carbohydrate conjugated aromatics, 12 and peptide amphiphiles. 13 However, few examples exist on the use of 1D supramolecular polymers for use in intracellular delivery, [14][15][16] while they can serve as a potentially attractive platform.…”

Section: 5mentioning

confidence: 99%