Nanoscale Inhomogeneities in Thermoresponsive Polymers

Kurzbach, Dennis; Junk, Matthias J. N.; Hinderberger, Dariush

doi:10.1002/marc.201200617

Cited by 73 publications

(115 citation statements)

References 87 publications

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“…37 The rationale behind our approach is that 16-DSA is likely to interact strongly with desolvated aggregates of ELPs above their LCST. We also performed a scouting study using a frequently used more hydrophilic probe, TEMPO ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) 3 but as it does not show significant interactions with ELPs due to diminishing hydrophobic attraction, we did not use it further (see the Supporting Information Figure S6). The ELP concentration was 1 wt% and the 16-DSA concentration was 1 mM in all the experiments reported herein.…”

Section: Side Chain Hydrophobicity and Backbone Chain Length Affect Tmentioning

confidence: 99%

“…The parameter a iso of species B increases with temperature for ELPs A 5 V 5 /A 2 V 8 /V-y (Figure 2b), which is a consequence of increasing probe-site exchange frequencies between ELP aggregates and solvent within the regime of slow exchange 35 due to increasing diffusional displacement with temperature (see Figure 3). 3 Hence, in aggregates of longer and more hydrophobic ELPs, the probes sense less water in their immediate vicinity (probably through residual backbone- or side-chain hydration) than in shorter and more hydrophilic ELP aggregates. This deduction is further corroborated by the T c,Turbidimetry s and T c,EPR s, which indicate decreasing stability of bound hydration shells with increasing main chain length and side chain hydrophobicity (see Table 1).…”

Section: Side Chain Hydrophobicity and Backbone Chain Length Affect Tmentioning

confidence: 99%

“…For synthetic LCST polymers, one often observes that the onset of the phase transition (proceeding via local collapse and nanoscale inhomogeneities), 3 detectable by spin probing CW EPR, is located at lower temperatures than the macroscopic LCST typically detected by methods like turbidimetry. 34 In contrast, we observe that the macroscopic LCST 21,39 of ELPs, T c,Turbidimetry , generally coincides with the onset of nanoscopic collapse, T c,EPR (see Table 1).…”

Section: Cooperativity Of the Inverse Phase Transitionmentioning

confidence: 99%

“…CW EPR is an underutilized but powerful spectroscopic method that can report the polarity and hydrophilicity/hydrophobicity in complex aggregates of soft matter systems (like collapsed LCST polymers) on a nanoscopic length scale. 3 Although CW EPR offers a potent and simple methodology to examine the solvation of polymers, it has only been used to study ELPs in one previous study. Covalent conjugation of an EPR-active nitroxide spin label to an ELP was employed with the goal of using this conjugate as a “molecular thermometer” to monitor mild clinical hyperthermia in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Hydration Layer Coupling and Cooperativity in Phase Behavior of Stimulus Responsive Peptide Polymers

et al. 2013

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It is shown that hydrophilic (backbone) and hydrophobic (side chain) hydration layers of elastin-like polypeptides (ELPs), a class of stimulus responsive peptide polymers that exhibit lower critical solution temperature (LCST) phase transition behavior, can exist in a coupled and decoupled state. The decoupled hydration state consists of hydrophobic and hydrophilic hydration layers that respond independently to temperature while the coupled hydration state is characterized by a common, cooperative dehydration of both hydration layers. It is further shown that the primary sequence of an ELP can be tuned to exhibit either of the hydration layer coupling modes. Charged side chains lead to decoupling, while strongly hydrophobic side chains trigger stronger interaction between hydrophilic and hydrophobic hydration, leading to coupling of both layers. Further, for aprotic residues this coupling is fostered by decreasing bulkiness of hydrophobic side chains due to larger hydration numbers and water molecules mediating coupling between side chain and backbone hydration shells. For coupled hydration shells, the LCST phase transition characterized by spin probing continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy is reminiscent of a first order process even on nanoscopic length scales. In contrast, analogous synthetic polymers exhibit nanoscale phase transitions over a broad temperature range, indicating that their nanoscale phase behavior is not of first order. Hence, our results indicate that ELPs are the first identified class of polymers that exhibit a first-order inverse phase transition on nanoscopic length scales. These results may also provide insights into the role of hydration layers in governing the structure-function relationship of intrinsically disordered proteins.

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Section: Side Chain Hydrophobicity and Backbone Chain Length Affect Tmentioning

confidence: 99%

Section: Side Chain Hydrophobicity and Backbone Chain Length Affect Tmentioning

confidence: 99%

Section: Cooperativity Of the Inverse Phase Transitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydration Layer Coupling and Cooperativity in Phase Behavior of Stimulus Responsive Peptide Polymers

et al. 2013

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“…Similar molecular scale observations of a broad transition temperature range have recently been reported for thermoresponsive dendronized polymers using EPR spectroscopy. 64,65 The question then remains how CLP and P3TMAHT interact below and above the LCST. 2D 1 H− 1 H NOESY spectra are illustrated in Figure 6b and c, respectively.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Temperature-Regulated Fluorescence and Association of an Oligo(ethyleneglycol)methacrylate-Based Copolymer with a Conjugated Polyelectrolyte—The Effect of Solution Ionic Strength

et al. 2013

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Aqueous mixtures of a dye-labeled non-ionic thermoresponsive copolymer and a conjugated cationic polyelectrolyte are shown to exhibit characteristic changes in fluorescence properties in response to temperature and to the presence of salts, enabling a double-stimuli responsiveness. In such mixtures at room temperature, i.e., well below the lower critical solution temperature (LCST), the emission of the dye is strongly quenched due to energy transfer to the polycation, pointing to supramolecular interactions between the two macromolecules. Increasing the concentration of salts weakens the interpolymer interactions, the extent of which is simultaneously monitored from the change in the relative emission intensity of the components. When the mixture is heated above its LCST, the transfer efficiency is significantly reduced, signaling a structural reorganization process, however, surprisingly only if the mixture contains salt ions. To elucidate the reasons behind such thermo- and ion-sensitive fluorescence characteristics, we investigate the effect of salts of alkali chlorides, in particular of NaCl, on the association behavior of these macromolecules before and after the polymer phase transition by a combination of UV-vis, fluorescence, and (1)H NMR spectroscopy with light scattering and small-angle neutron scattering measurements.

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An Atomistic View on the Mechanism of Diatom Peptide‐Guided Biomimetic Silica Formation

Kozak,

Brandis,

Pötzl

et al. 2024

Advanced Science

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Deciphering nature's remarkable way of encoding functions in its biominerals holds the potential to enable the rational development of nature‐inspired materials with tailored properties. However, the complex processes that convert solution‐state precursors into solid biomaterials remain largely unknown. In this study, an unconventional approach is presented to characterize these precursors for the diatom‐derived peptides R5 and synthetic Silaffin‐1A1 (synSil‐1A1). These molecules can form defined supramolecular assemblies in solution, which act as templates for solid silica structures. Using a tailored structural biology toolbox, the structure‐function relationships of these self‐assemblies are unveiled. NMR‐derived constraints are employed to enable a recently developed fractal‐cluster formalism and then reveal the architecture of the peptide assemblies in atomistic detail. Finally, by monitoring the self‐assembly activities during silica formation at simultaneous high temporal and residue resolution using real‐time spectroscopy, the mechanism is elucidated underlying template‐driven silica formation. Thus, it is demonstrated how to exercise morphology control over bioinorganic solids by manipulating the template architectures. It is found that the morphology of the templates is translated into the shape of bioinorganic particles via a mechanism that includes silica nucleation on the solution‐state complexes’ surfaces followed by complete surface coating and particle precipitation.

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Nanoscale Inhomogeneities in Thermoresponsive Polymers

Cited by 73 publications

References 87 publications

Hydration Layer Coupling and Cooperativity in Phase Behavior of Stimulus Responsive Peptide Polymers

Hydration Layer Coupling and Cooperativity in Phase Behavior of Stimulus Responsive Peptide Polymers

Temperature-Regulated Fluorescence and Association of an Oligo(ethyleneglycol)methacrylate-Based Copolymer with a Conjugated Polyelectrolyte—The Effect of Solution Ionic Strength

An Atomistic View on the Mechanism of Diatom Peptide‐Guided Biomimetic Silica Formation

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