How Far Are Single-Chain Polymer Nanoparticles in Solution from the Globular State?

Pomposo, José A.; Perez-Baena, Irma; Verso, Federica Lo; Moreno, Angel J.; Arbe, Arantxa; Colmenero, Juan

doi:10.1021/mz500354q

Cited by 171 publications

(284 citation statements)

References 58 publications

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“…In fact, Pomposo et al recently reported that apart from our previously reported BTA-based SCPNs 23,27,47 many SCPNs adopt open, sparse morphologies resembling those of intrinsically disordered proteins, instead of globular conformations. 61 Thus, we performed SAXS measurements on p0%, p5%, and p10% to study the effect of BiPy-BTA incorporation and solvent composition on the shape and internal structure of the BiPy-BTA-based SCPNs.…”

Section: ■ Resultsmentioning

confidence: 99%

The Coil-to-Globule Transition of Single-Chain Polymeric Nanoparticles with a Chiral Internal Secondary Structure

et al. 2015

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The intramolecular folding of chiral single polymeric chains into single-chain polymeric nanoparticles (SCPNs) via π-stacking was investigated. To this end, hydrophilic polymers grafted with structuring, chiral 3,3′-bis(acylamino)-2,2′-bipyridine-substituted benzene-1,3,5-tricarboxamides (BiPy-BTAs) units were prepared via ring-opening metathesis polymerization (ROMP). A combination of spectroscopic and scattering techniques was employed to obtain a better understanding of the folding behavior and the chiral internal structure of these systems. Circular dichroism spectroscopy showed that the folding of the polymer is highly dependent on the solvent quality and temperature. The folding process in water was finetuned via the addition of a good cosolvent (tetrahydrofuran), resulting in an optimal balance between the conformational freedom of the polymer's backbone and the stability of the π-stacked units. Small-angle X-ray scattering (SAXS) experiments showed that the shape of the SCPNs is controlled by the formation of a chiral internal secondary structure. ■ INTRODUCTIONReproducing the specific way in which Nature folds its linear polymers into perfectly defined nanostructures by using synthetic systems is a major goal in the field of synthetic macromolecular design. A new route to obtain such structures makes use of precisely engineered polymers to construct singlechain polymeric nanoparticles (SCPNs). 1−6 In this biomimetic approach, linear polymers are folded into nanometer-sized objects via intramolecular cross-links between the polymer's cross-linkable grafts. So far, several types of intramolecular cross-links have been explored, ranging from covalent 7−13 to dynamic covalent 14−17 to noncovalent. 18−27 The structure-forming elements are usually attached as side chains to a linear polymer backbone either via direct copolymerization or by postfunctionalization. 7,15,28−30 The introduction of click chemistry 31,32 and advances in the field of synthetic polymer chemistry, 33−36 introducing robust controlled/living polymerization techniques tolerant toward functional groups, have both been crucial to obtain tailored polymeric chains, which resulted in the flourishing field of SCPNs. The modular nature of the single chain approach allows the design of nanoparticles that have potential in various applications via the implementation of specific active groups. Rudimentary enzyme analogues have already been prepared using SCPNs, by incorporation of catalytically active groups in the foldable polymer chain. 37−42 Furthermore, SCPNs functioning as chemosensors, contrast agents, and drug carriers have been prepared. 13,43−46 Since structure and function are closely related, we studied in detail how a polymer with pendant, hydrogen-bond-based supramolecular motifs folds into a SCPN in organic solvents and in water. 20,23,27,37 In a recent study, we investigated the shape and size of SCPNs in water and assessed the effect of temperature and cosolvent on their formation. 47 In the research presented here, we extend thi...

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Section: ■ Resultsmentioning

confidence: 99%

The Coil-to-Globule Transition of Single-Chain Polymeric Nanoparticles with a Chiral Internal Secondary Structure

et al. 2015

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“…22,50,68,91,98 Pomposo and co-workers analyzed a large number of SCNP in solution using a combination of SAXS and SANS. 95 Polystyrene (PS)-based systems with 30 different precursors and 11 different cross-linking chemistries including covalent, dynamic covalent, and noncovalent were studied in comparison to PS globules of the same molecular weight. Results indicated that the SCNP stray from compact globular proteins and rather take on a nonglobular, noncompact structure resembling intrinsically disordered proteins.…”

Section: ■ the Pressing Challengesmentioning

confidence: 99%

What Is Next in Single-Chain Nanoparticles?

2015

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With the increasing appeal of nanotechnology, there is a demand for development of synthetic techniques for the fabrication of nanosized objects that allow for precise size control and tailored functionalization. To this end, the collapse or folding of single polymer chains into architecturally defined nanostructures is a rapidly growing research topic in polymer science. Many synthetic approaches have been developed for the formation of single-chain nanoparticles (SCNP), and a variety of characterization methods and computational efforts have been utilized to detail their formation and probe their morphological characteristics. Interest in this field continues to grow partially due to the variety of potential applications of SCNP including catalysis, sensors, nanoreactors, and nanomedicine. While numerous developments have been made, the field is continuing to evolve, and there are still many unanswered questions regarding synthesis and characterization of SCNP. This Perspective serves to identify recent accomplishments in the synthesis and characterization of SCNP while distinguishing areas that are in need of advancement and innovation to move forward. This includes exploring more complex synthetic strategies, obtaining folding control, employing nanoparticle functionalization, developing scalable methods, investigating hierarchical self-assembly of SCNP, and exploiting unique characterization techniques and in-depth simulations.

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“…Recent investigations by experiments and simulations have highlighted that, in general, the usual synthesis protocols in good solvent conditions produce SCNPs with open, sparse conformations 8,9,11,12 . As revealed by extensive simulations 11 , this feature originates from a fundamental property: the self-avoiding conformations of the linear precursors in good solvent.…”

Section: Introductionmentioning

confidence: 99%

Tunable slow dynamics in a new class of soft colloids

et al. 2016

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By means of extensive simulations, we investigate concentrated solutions of globular single-chain nanoparticles (SCNPs), an emergent class of synthetic soft nano-objects. By increasing the concentration, the SCNPs show a reentrant behaviour in their structural and dynamical correlations, as well as a soft caging regime and weak dynamic heterogeneity. The latter is confirmed by validation of the Stokes-Einstein relation up to concentrations far beyond the overlap density. Therefore SCNPs arise as a new class of soft colloids, exhibiting slow dynamics and actualizing in a real system structural and dynamical anomalies proposed by models of ultrasoft particles. Quantitative differences in the dynamical behaviour depend on the SCNP deformability, which can be tuned through the degree of internal cross-linking.

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How Far Are Single-Chain Polymer Nanoparticles in Solution from the Globular State?

Cited by 171 publications

References 58 publications

The Coil-to-Globule Transition of Single-Chain Polymeric Nanoparticles with a Chiral Internal Secondary Structure

The Coil-to-Globule Transition of Single-Chain Polymeric Nanoparticles with a Chiral Internal Secondary Structure

What Is Next in Single-Chain Nanoparticles?

Tunable slow dynamics in a new class of soft colloids

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