Dehydrated native biopolymers - a unique representative of glassy systems

Tsereteli, G. I.; Belopolskaya, T. V.; Grunina, N. A.

doi:10.1007/s10973-008-9023-1

Cited by 13 publications

(10 citation statements)

References 12 publications

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“…Under the influence of heating all studied scaffolds exhibit a broad endothermic peak around 90°C due to an advanced dehydration. The obtained results are in good agreement with those reported for Coll and SS separately investigated 42–45. According to our data, as the SS content increases, this peak is shifted to higher temperatures compared with Coll (from 92°C up to 100°C) probably due to an increased number of hydrogen bonds, established between the Coll and SS molecules, which partially hinders the dehydration of Coll.…”

Section: Resultssupporting

confidence: 92%

Superporous collagen‐sericin scaffolds

Lungu

Kaya

Stancu

et al. 2012

J of Applied Polymer Sci

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Superporous materials based on two proteins, collagen and sericin were synthesized by freeze-drying considering various ratios between the two proteins. To evaluate the influence of sericin content on the structure/properties relationship, the obtained scaffolds were further characterized using spectroscopic analysis, thermal, and mechanical techniques. Scanning electron microscopy was used to investigate the morphological structure of the scaffolds and the swelling properties as well as the stability of the scaffolds were also assessed.

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Section: Resultssupporting

confidence: 92%

Superporous collagen‐sericin scaffolds

Lungu

Kaya

Stancu

et al. 2012

J of Applied Polymer Sci

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“…3. Adsorption was reversible as reported by Tsereteli et al [12], nearly the same adsorption isotherm was obtained in three successive runs. The water vapour effected reversibly DNA molecules.…”

Section: Adsorption Equilibriumsupporting

confidence: 87%

“…System was evacuated to 0.1 Pa pressure. 50°C outgassing temperature was chosen to be lower than the denaturation temperature of calf thymus at low moisture contents [12]. Saturated water vapour having 3.1·10 3 Pa pressure at 25°C was sent to 3 dm 3 adsorption chamber initially under 0.1 Pa pressure at a very slow rate (1.1·10 -3 cm 3 s -1 ) to keep the sample in equilibrium with water vapour.…”

Section: Methodsmentioning

confidence: 99%

Water vapour adsorption on DNA

Balköse

Alp

Ülkü

2008

J Therm Anal Calorim

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DNA is a molecule which is present in the nucleus of each living cell. It is the molecule which synthesizes proteins. DNA conformation [1], electrical conductivity [2] and density [3] depend on the amount of water it contains. The phosphate groups, nitrogen and oxygen atoms of the base pairs in DNA bind to water molecules by hydrogen bonding. DNA adsorbs moisture from atmosphere and it is a water soluble macromolecule. The state of water in DNA has been investigated by X-ray diffraction, by inelastic neutron scattering [4] and melting of frozen water in DNA [5] by previous workers. The bound water in frozen DNA does not show ice melting endotherm. This is due to distribution of electric charges around phosphate groups. Dielectric study on hydration of DNA in water-ethanol solutions showed that 19 and 13 molecules of water per nucleotide are required for B-DNA and A-DNA respectively to keep the double helix. Studies of water vapour adsorption of DNA films by IR spectroscopy have shown that the hydrogen bonded water peak maxima shifted from 3473 to 3583 cm -1 as moisture content increases. This was attributed to the formation of a thin liquid water film on the surface of DNA [6].The interaction between DNA and water were described by quantum mechanical methods [2] and by molecular dynamics [7]. Water network around simulated duplexes was more conformation specific rather than sequence specific [7]. Water influences DNA stability and the contribution of water molecules to the energy of DNA helical structure was found from the energy spectrum of the bound water and enthalpy of helix-coil transformation [8]. Energy change was inversely proportional to amount of bound water per nucleotide.In studying DNA by IR spectroscopy diffuse reflectance The state of the sample could change during sample preparation, handling and measurement stages using these techniques.This research aims studying water vapour adsorption of DNA in situ. Outgassing the samples in vacuum and sending water vapour at controlled rate and pressure prevented any change in state of the sample between outgassing and measuring stages. No change in state of the sample occurs since the sample was not transferred from preparation environment to measuring environment. While water vapour was sent continuously at a low rate in gravimetric system, water vapour at different pressures was sent in steps in FTIR Drift cell and microcalorimeter cell. ExperimentalIn the present study sodium salt DNA obtained from calf tymus (Sigma) was used.The morphology of the fibres was investigated by scanning electron microscopy using Philips VL30 SFEG SEM.Equilibrium and kinetics of water vapour adsorption on calf thymus DNA was studied by Cahn gravimetric adsorption system described in a previous paper [11]. The system has Edwards ultra high vacuum system and all vacuum glass valves were from Scientific Glass Company. Adsorption isotherm of water vapour on DNA at 25°C was determined after Analysis and Calorimetry, Vol. 94 (2008)

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“…As it is known, in reality the amorphous phase in native granules is not completely amorphous since it is connected with the crystalline phase by common molecular chains. This structural peculiarity is reflected both in the ability of native granules to the limited swell (Eliasson & Gudmundsson, 1996) and in the process of vitrification of native starches (Slade & Levine, 1988;Tsereteli et al, 2008;Zeleznak & Hoseney, 1987). Only after the destruction of a native granule its amorphous phase becomes truly amorphous.…”

Section: Melting Heat Of Frozen Water In the Amorphous Starchesmentioning

confidence: 99%