Single-particle thermal diffusion of charged colloids: Double-layer theory in a temperature gradient

Dhont, Jan K. G.; Briels, Willem J.

doi:10.1140/epje/i2007-10264-6

Cited by 58 publications

(66 citation statements)

References 18 publications

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“…Further confirmation of the approach was found from the study of quartz beads [16]. Extensions of the theory were reported in [17]. Subsequent experiments on polystyrene beads [18] came to different conclusions concerning the size dependence.…”

Section: Basics Of Thermophoresismentioning

confidence: 76%

Thermophoresis of single stranded DNA

2010

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The manipulation and analysis of biomolecules in native bulk solution is highly desired; however, few methods are available. In thermophoresis, the thermal analog to electrophoresis, molecules are moved along a microscopic temperature gradient. Its theoretical foundation is still under debate, but practical applications for analytics in biology show considerable potential. Here we measured the thermophoresis of highly diluted single stranded DNA using an all-optical capillary approach. Temperature gradients were created locally by an infrared laser. The thermal depletion of oligonucleotides of between 5 and 50 bases in length were investigated by fluorescence at various salt concentrations. To a good approximation, the previously tested capacitor model describes thermophoresis: the Soret coefficient linearly depends on the Debye length and is proportional to the DNA length to the power of 0.35, dictated by the conformation-based size scaling of the diffusion coefficient. The results form the basis for quantitative DNA analytics using thermophoresis.

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Section: Basics Of Thermophoresismentioning

confidence: 76%

Thermophoresis of single stranded DNA

2010

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“…Several theoretical approaches exist to describe thermodiffusion (or thermophoresis) of liquid mixtures, polymer solutions, and colloidal suspensions (10)(11)(12)(13). The review by Würger (11) introduces theoretical concepts for colloids, and the book chapter by Wiegand (13) gives an overview on the basic physics of the effect.…”

Section: Significancementioning

confidence: 99%

Accumulation of formamide in hydrothermal pores to form prebiotic nucleobases

Niether

Afanasenkau

Dhont

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Formamide is one of the important compounds from which prebiotic molecules can be synthesized, provided that its concentration is sufficiently high. For nucleotides and short DNA strands, it has been shown that a high degree of accumulation in hydrothermal pores occurs, so that temperature gradients might play a role in the origin of life [Baaske P, et al. (2007) Proc Natl Acad Sci USA 104(22): 9346−9351]. We show that the same combination of thermophoresis and convection in hydrothermal pores leads to accumulation of formamide up to concentrations where nucleobases are formed. The thermophoretic properties of aqueous formamide solutions are studied by means of Infrared Thermal Diffusion Forced Rayleigh Scattering. These data are used in numerical finite element calculations in hydrothermal pores for various initial concentrations, ambient temperatures, and pore sizes. The high degree of formamide accumulation is due to an unusual temperature and concentration dependence of the thermophoretic behavior of formamide. The accumulation fold in part of the pores increases strongly with increasing aspect ratio of the pores, and saturates to highly concentrated aqueous formamide solutions of ∼85 wt% at large aspect ratios. Time-dependent studies show that these high concentrations are reached after 45-90 d, starting with an initial formamide weight fraction of 10 −3 wt % that is typical for concentrations in shallow lakes on early Earth.concentration problem | hydrothermal vents | molecular evolution | origin-of-life problem | thermophoresis T hermophoresis has been suggested as an active transport mechanism to reach high concentrations of prebiotic molecules to culminate in the formation of RNA (1). A still open question is whether thermophoresis can also be a possible mechanism to form prebiotic nucleobases from simple molecules such as hydrogen cyanide (HCN) and formamide (FA). Already for almost 50 years, FA has been discussed as an important compound from which prebiotic molecules originate (2-7). It has been shown that all known nucleobases can be synthesized from aqueous FA solutions (4). In diluted HCN solutions, polymerization of HCN to form nucleobases becomes favored over hydrolysis of HCN at concentrations of 0.03-0.3 wt % (8). To our knowledge, there are no similar studies of diluted FA solutions. Taking into account the faster hydrolysis of FA (3), we estimated that a 100-timeshigher concentration between 3 wt % and 33 wt % should be sufficient for the synthesis of prebiotic molecules in aqueous solutions. In the ocean during the early stages of Earth, the natural occurring concentrations at a low temperature (10°C) and a pH between 6 and 8 are estimated to be only on the order of 10 −9 wt %, whereas, in shallow lakes (depth 10 m), due to vaporization and FA input from the atmosphere, higher concentrations of about 10 −3 wt % are possible (3). Still, these natural concentrations are far too small compared with those required for the formation of nucleobases.In this work, we perform numerical calculations ...

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“…7,8 Only specific aspects as the interaction contribution or charge effects in highly diluted solutions of colloidal dispersions have been considered so far. [9][10][11][12][13][14] The Ludwig-Soret effect for a binary fluid mixture is described by the flux J 1 of component 1 contains contributions of the concentration and the temperature gradient as follows 15…”

Section: Introductionmentioning

confidence: 99%