Density and Viscosity of Concentrated Aqueous Solutions of Polyethylene Glycol

González-Tello, P.; Camacho, F.; Blázquez, G.

doi:10.1021/je00015a050

Cited by 211 publications

(175 citation statements)

References 6 publications

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“…Fig. 6 c and d shows, respectively, DTLM and fluorescence microscopy images of the same sample held at T ϭ 75°C for 1 h, a time sufficient to thoroughly disperse nDNA LC domains into the SS nDNA background, especially because highly concentrated PEG solutions typically are less viscous than the nDNA mixtures (13). We found that nDNA domains did not dissolve, so that by cooling again, domains formed in the same locations as they were previously, an occurrence never observed in nDNA mixtures.…”

mentioning

confidence: 99%

Phase separation and liquid crystallization of complementary sequences in mixtures of nanoDNA oligomers

Zanchetta

Nakata

Buscaglia

et al. 2008

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

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Using optical microscopy, we have studied the phase behavior of mixtures of 12-to 22-bp-long nanoDNA oligomers. The mixtures are chosen such that only a fraction of the sample is composed of mutually complementary sequences, and hence the solutions are effectively mixtures of single-stranded and double-stranded (duplex) oligomers. When the concentrations are large enough, such mixtures phase-separate via the nucleation of duplex-rich liquid crystalline domains from an isotropic background rich in single strands. We find that the phase separation is approximately complete, thus corresponding to a spontaneous purification of duplexes from the single-strand oligos. We interpret this behavior as the combined result of the energy gain from the end-to-end stacking of duplexes and of depletion-type attractive interactions favoring the segregation of the more rigid duplexes from the flexible single strands. This form of spontaneous partitioning of complementary nDNA offers a route to purification of short duplex oligomers and, if in the presence of ligation, could provide a mode of positive feedback for the preferential synthesis of longer complementary oligomers, a mechanism of possible relevance in prebiotic environments.condensation ͉ nucleation ͉ depletion ͉ prebiotic ͉ PEG M olecular crowding of cellular interior is known to play a role in the spontaneous organization of biological macromolecules (1). Several biochemical and physiological processes are found to be influenced by strong packing constraints (2, 3), and complex ordered arrangements, such as liquid-crystalline mesophases, have been shown to arise from highly packed biomolecules (4). Of particular interest is the ordering of highly concentrated DNA in cell nuclei, which can lead to a variety of mesophases in vivo (5). However, whether such ordering caused by packing constraints had represented an evolutionary advantage remains an open question.Concentrated solutions of fully hybridized nanoDNA (nDNA) exhibit various liquid crystalline forms of supramolecular ordering, promoted by end-to-end adhesion of the paired bases at the terminals of the duplexes. This behavior has been reported recently for a wide set of self-complementary (SC) 6-to 20-bp nDNA sequences and for mutually complementary sequences in the same length range (6). Here we explore the phase behavior of mixtures of nDNA in which only some of the sequences are complementary, thus able to pair in double strands (DSs), and part of the sequences are not, and thus always remain in the solution as single strands (SSs). We have found that in concentrated mixtures of duplex and SS nDNA, the system phaseseparates into duplex-rich liquid crystal (LC) domains coexisting with a duplex-poor isotropic phase, leading to the physical segregation of 4-to 6-nm-long complementary chains from noncomplementary ones. This phase separation is a collective effect of the duplex and SS nDNA because the duplexes alone would not form LCs in such solutions, their concentration being well below that required for LC forma...

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mentioning

confidence: 99%

Phase separation and liquid crystallization of complementary sequences in mixtures of nanoDNA oligomers

Zanchetta

Nakata

Buscaglia

et al. 2008

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

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“…Figure 3b shows air being injected into a mixtureofwater and 10% by weight polyethylene glycol (PEG). PEG is a watersoluble polymer that makes the Newtonian fluidmore viscous, with the viscosity increasing as the PEG concentration increases [50]. Although viscosity was not measured iir this study, Gonzalez-Tello et al [50] indicate the viscosity.…”

Section: X-ray Radiography Imagingmentioning

confidence: 68%

Visualizing Fluid Flows With X-Rays

Heindel

Jensen

Gray

2007

Volume 1: Symposia, Parts a and B

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There are several methods available to visualize fluid flows when one has optical access. However, when optical access is limited to near the boundaries or not available at all, alternative visualization methods are required. This paper will describe flow visualization using an X-ray system that is capable of digital X-ray radiography, digital X-ray stereography, and digital X-ray computed tomography (CT). The unique X-ray flow visualization facility will be briefly described, and then flow visualization of various systems will be shown. Radiographs provide a two-dimensional density map of a three dimensional process or object. Radiographic images of various multiphase flows will be presented. When two X-ray sources and detectors simultaneously acquire images of the same process or object from different orientations, stereographic imaging can be completed; this type of imaging will be demonstrated by trickling water through packed columns and by absorbing water in a porous medium. Finally, local time-averaged phase distributions can be determined from X-ray computed tomography (CT) imaging, and this will be shown by comparing CT images from two different gas-liquid sparged columns.

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“…Viscosity of PEG increases dramatically with concentration as presented in Ref. 8. A minimal voltage of 6 V at 20 kHz was sent to the piezodispenser and PEG 8000 at 15%, 20%, and 25% concentration was dispensed.…”

Section: -2mentioning

confidence: 99%

“…At a temperature of 298 K, 20% PEG 8000 has a viscosity of 20.2 cp according to Ref. 8, while 30% PEG 8000 has a listed viscosity of 50.9 cp. The maximum viscosity that was dispensed was 30% PEG 8000 at 35 psi with a piezoelectric voltage of 75 V. It was impossible to distinguish separate drops with this high viscosity PEG, and there was significant fluid buildup and dripping from the tip during the starting and stopping of dispensing.…”

Section: -2mentioning

confidence: 99%

A novel pressure-driven piezodispenser for nanoliter volumes

McGuire

Fisher

Holl

et al. 2008

Review of Scientific Instruments

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A successful dispensing device has been built for use in biotechnology applications requiring nanoliter volume liquid transfer. Air pressure is used as the primary driving force and is controlled via a high speed miniature solenoid valve as opposed to many existing systems that use a valve in line with constantly pressurized fluid to start and stop the dispensing action. This automated pressure-driven system is used to improve a typical piezodriven microdispenser. The resulting system is much less prone to failures resulting from air entrainment and can dispense much higher viscosity fluids than the microdispenser alone.

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Density and Viscosity of Concentrated Aqueous Solutions of Polyethylene Glycol

Cited by 211 publications

References 6 publications

Phase separation and liquid crystallization of complementary sequences in mixtures of nanoDNA oligomers

Phase separation and liquid crystallization of complementary sequences in mixtures of nanoDNA oligomers

Visualizing Fluid Flows With X-Rays

A novel pressure-driven piezodispenser for nanoliter volumes

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