Thermophoresis in self-associating systems: probing poloxamer micellization by opto-thermal excitation

Lattuada, Enrico; Buzzaccaro, Stefano; Piazza, Roberto

doi:10.1039/c8sm02386g

Cited by 9 publications

(7 citation statements)

References 53 publications

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“…We therefore conclude that the thermophoretic behaviour of micelles also follows the empirical correlation with logP. In a very recent study Lattuada et al [186] investigated an industrially used block copolymer, poloxamer P407, which shows a complex phase behaviour including multi phases. For this system they observed a double sign change behaviour at the cmt as it has also been observed for simple salts [155,156].…”

Section: Non-ionic and Ionic Micellar Systemsmentioning

confidence: 56%

“…There are only a few studies of micellar system [158][159][160][183][184][185][186] by thermal lens experiments and by TDFRS. Typically, instruments like optical beam deflection technique and thermogravitational columns are not suitable since those experimental techniques require temperature differences of a couple of degrees so that, depending on the phase diagram, the shape and/or size of the micelles might be different at the warm and cold side.…”

Section: Non-ionic and Ionic Micellar Systemsmentioning

confidence: 99%

“…Three studies investigated the thermophoretic behaviour in the vicinity of the critical micelle concentration (cmc) and temperature (cmt) [183,184,186]. In all studies it was observed that the thermophoretic behaviour shows a pronounced change at the cmc or cmt.…”

Section: Non-ionic and Ionic Micellar Systemsmentioning

confidence: 99%

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Thermophoresis of biological and biocompatible compounds in aqueous solution

Niether

Wiegand

2019

J. Phys.: Condens. Matter

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With rising popularity of microscale thermophoresis for the characterisation of protein-ligand binding reactions and possible applications in microfluidic devices, there is a growing interest in considering thermodiffusion in the context of life sciences. But although the understanding of thermodiffusion in non-polar mixtures has grown rapidly in recent years, predictions for associated mixtures like aqueous solutions remain challenging. This review aims to give an overview of the literature on thermodiffusion in aqueous systems, show the difficulties in theoretical description that arise from the non-ideal behaviour of water-mixtures, and highlight the relevance of thermodiffusion in a biological context. We find that the thermodiffusion in aqueous systems is dominated by contributions from heat of transfer, hydrogen bond interactions and charge effects. However, the separation of these effects is often difficult, especially in case of biological systems where a systematic exclusion of contributions may not be feasible.

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Section: Non-ionic and Ionic Micellar Systemsmentioning

confidence: 56%

Section: Non-ionic and Ionic Micellar Systemsmentioning

confidence: 99%

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Thermophoresis of biological and biocompatible compounds in aqueous solution

Niether

Wiegand

2019

J. Phys.: Condens. Matter

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“…Unless otherwise stated, all measurements were performed with a laser power P = 40 mW. As the temperature increase on the beam axis could be estimated as ∆T 0.3Pb/κ [25], for this value of P we had ∆T 1 • C. More detailed information on the TL setup can be found in [32]. A typical TL signal from a suspension of PniPAM microgel particles is shown in Figure 2.…”

Section: Thermal Lens Principle and Thermal Expansivity Measurementsmentioning

confidence: 99%

Thermal Lens Measurements of Thermal Expansivity in Thermosensitive Polymer Solutions

2023

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The weak absorption of a laser beam generates in a fluid an inhomogeneous refractive index profile acting as a negative lens. This self-effect on beam propagation, known as Thermal Lensing (TL), is extensively exploited in sensitive spectroscopic techniques, and in several all-optical methods for the assessment of thermo-optical properties of simple and complex fluids. Using the Lorentz–Lorenz equation, we show that the TL signal is directly proportional to the sample thermal expansivity α, a feature allowing minute density changes to be detected with high sensitivity in a tiny sample volume, using a simple optical scheme. We took advantage of this key result to investigate the compaction of PniPAM microgels occurring around their volume phase transition temperature, and the temperature-driven formation of poloxamer micelles. For both these different kinds of structural transitions, we observed a significant peak in the solute contribution to α, indicating a decrease in the overall solution density—rather counterintuitive evidence that can nevertheless be attributed to the dehydration of the polymer chains. Finally, we compare the novel method we propose with other techniques currently used to obtain specific volume changes.

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“…Thermophoresis is a sophisticated phenomenon influenced by various factors (e.g. temperature, pH, ion concentration, solvent expansivity, particle shape and surface chemistry) that is yet to be fully understood [ 39 – 41 ]. Nonetheless, negative S T values—demonstrating accumulation at warmer regions—have been reported for microparticles and bacterial (and other) cells in aqueous solutions in several recent studies [ 37 , 42 – 45 ], including a small number of investigations using fiber-optic devices [ 24 , 46 , 47 ].…”

Section: Introductionmentioning

confidence: 99%

Plasmonic optical fiber for bacteria manipulation—characterization and visualization of accumulation behavior under plasmo-thermal trapping

Kim

Yeatman

Thompson

2021

Biomed. Opt. Express

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In this article, we demonstrate a plasmo-thermal bacterial accumulation effect using a miniature plasmonic optical fiber. The combined action of far-field convection and a near-field trapping force (referred to as thermophoresis)—induced by highly localized plasmonic heating—enabled the large-area accumulation of Escherichia coli . The estimated thermophoretic trapping force agreed with previous reports, and we applied speckle imaging analysis to map the in-plane bacterial velocities over large areas. This is the first time that spatial mapping of bacterial velocities has been achieved in this setting. Thus, this analysis technique provides opportunities to better understand this phenomenon and to drive it towards in vivo applications.

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Thermophoresis in self-associating systems: probing poloxamer micellization by opto-thermal excitation

Abstract: Thermophoresis in a self-associating system displays surprising features predicted by a simple local balance approach to temperature-dependent association processes.

Cited by 9 publications

References 53 publications

Thermophoresis of biological and biocompatible compounds in aqueous solution

Thermophoresis of biological and biocompatible compounds in aqueous solution

Thermal Lens Measurements of Thermal Expansivity in Thermosensitive Polymer Solutions

Plasmonic optical fiber for bacteria manipulation—characterization and visualization of accumulation behavior under plasmo-thermal trapping

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