The cryoprotective properties of hydroxyethyl starch investigated by means of differential thermal analysis

Körber, Christoph; Scheiwe, M.W.

doi:10.1016/0011-2240(80)90008-5

Cited by 33 publications

(17 citation statements)

References 14 publications

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“…7 It is known that HES does not crystallize, and therefore dry HES samples must be in the glassy state. 1,2,11 The air-dried HES-PBS sample, however, did not have an endothermic relaxation peak, and the glass transition was detected at ,130°C (Fig. 2B).…”

Section: Resultsmentioning

confidence: 87%

“…1,2 The difference might be due to the different HES molecular weight, substitution ratio, and high NaCl/HES mass ratio used in those two later studies. Differential enthalpy of ice melting as a function of water content was calculated by taking the first derivative of the fitted quadratic equation (Fig.…”

Section: Unfrozen Water In the Maximally Fcdmentioning

confidence: 94%

“…In order to understand the protective properties of HES, earlier studies investigated the liquidus surface, eutectic line, and waterbinding capacity of the ternary HES-NaCl-H 2 O system. [1][2][3] Attempts were also made to establish an extended phase diagram for the HES solutions by including glass transition and devitrification information. 3,4 However, there were only two reliable data points for glass transition temperatures (T g ) of HES solutions: 217°C for the freeze concentrate of the ternary HES-NaCl-H 2 O system (average molecular weight, 450,000; substitution ratio, 0.70-0.80) 3 and 2110°C for the quenched 56.4% (wt/wt) HES solution (average molecular weight, 67,000; substitution ratio, 0.50-0.55).…”

Section: Introductionmentioning

confidence: 99%

“…Difficulties in measuring the T g of HES samples have been encountered because of the polydispersity of HES samples, sample preparation techniques, and the low sensitivity of differential scanning calorimetry (DSC). [1][2][3][4]6 An alternative approach was recently used to estimate the T g of anhydrous pure HES 6 that involved the application of the Gordon-Taylor equation and the Fox equation. The T g of pure HES (average molecular weight, 200,000; substitution ratio, 0.40-0.55) was estimated to be ,44°C by extrapolating experimental T g data of freeze-dried HES-glucose mixtures and HES-trehalose mixtures.…”

Section: Introductionmentioning

confidence: 99%

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The Glass Transition Behaviors of Hydroxyethyl Starch Solutions

Sun¹,

Wagner²,

Connor³

2004

Cell Preservation Technology

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Despite the increasing use of hydroxyethyl starch (HES) as a cryo-and lyoprotectant, information about its glass transition behavior is scarce. The problem stems from the difficulty in detecting the glass transition of HES samples due to the polydispersity of HES and low sensitivity of calorimetric methods. Using an isothermal desorption (controlled air-drying) method and differential scanning calorimetry (DSC), the present study reports a complete glass state transition diagram of the HES-phosphate-buffered saline (HES-PBS) solution (average molecular weight, 262,600; substitution ratio, 0.46). This state diagram is described by the Gordon-Taylor equation. The glass transition temperature (T g ) of amorphous anhydrous solutes and the plasticization constant of water (k) as defined in the model are 406.3 K (133.1°C) and 4.75, respectively. T g depression of the HES-PBS system is less sensitive to water plasticization than other carbohydrates and biopolymers. Heat capacity change (DC p ) associated with glass transition is also hydration-dependent. The relationship between water content and DC p is defined by five hydration ranges, demonstrating complex hydration-dependent thermal behaviors. The thermal transition profile of the HES-PBS system depends on solute concentration. At solute concentrations .75% (wt/wt), no crystallization or devitrification was observed upon cooling or warming. Between 60% and 75%, the solution vitrified during slow cooling, but devitrified upon warming. Between 45% and 60%, the solution vitrified only at high cooling rates. Below ,45%, complete vitrification was not achieved, even at a cooling rate about 2,200°C/min. Incomplete vitrification and devitrification resulted in the formation of heterogeneous domains that contribute to a complex transition profile upon warming. Devitrification temperatures of the HES-PBS solutions were observed at 23.3 6 2.9°C (mean 6 standard deviation) above T g . Finally, the amount of unfrozen water in the freeze concentrate was calculated to be 0.328 g of water/g of solute in the HES-PBS system (i.e., 24.7%, wt/wt). The methodology described herein may be used to overcome the difficulty in glass transition determination of other cryo-and lyoprotectant systems. 55

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Section: Resultsmentioning

confidence: 87%

Section: Unfrozen Water In the Maximally Fcdmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Glass Transition Behaviors of Hydroxyethyl Starch Solutions

Sun¹,

Wagner²,

Connor³

2004

Cell Preservation Technology

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“…It may be ex pected that HES possesses a comparably weak in fluence on phase transition T° and produces little or no further depression of the freezing point when added to aqueous solutions of NaCl. In this regard, we have studied phase transitions by means of dif ferential thermal analysis (DTA) [7,8] for 57 test solutions, representing concentrations of NaCl and HES ranging between 0-21 and 0-40% (% = weight%), respectively. As would be expected, all eutectic values are located in the region of -21 °C, the eutectic T° for the NaCl-H20 binary system.…”

Section: Physical Sequences Occurring During Freezingmentioning

confidence: 99%

Cryopreservation of Human Erythrocytes with Hydroxyethyl Starch

Mishler¹

1979

Vox Sanguinis

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Synthese und eigenschaften von polymeren hydrogelen

Heitz

Krappitz

Stützel-Bilbao

et al. 1984

Angew. Makromol. Chem.

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Polymere Hydrogele sind aus physikalisch oder chemisch vernetzten, wasserlöslichen Polymeren aufgebaut. Eine physikalische Vernetzung ist durch eine Blockstruktur mit hydrophilen und hydrophoben Segmenten möglich. Die chemische Vernetzung ist durch Vernetzung wasserlöslicher Polymerer oder durch vernetzende Copolymerisation durchzuführen. Die für viele Anwendungen optimale Kugelgestalt der Polymerteilchen wird durch Suspensionspolymerisation erzeugt. Da hydrophile Polymere in der Regel wasserlösliche Monomere als Basis haben, müssen spezielle Techniken der Suspensionspolymerisation eingesetzt werden. Die Anwendung hydrophiler Gele als beliebig dimensionierbares wasserresevoir, als stationäre Phase in der Gel‐ und Affinitätschromatographie, als Träger für Enzyme oder als Wirkstoffdepot erfordert die Variation der Porenstruktur in einem weiten Bereich. Während bei kleinen Poren eine Regelung der Größe über den Vernetzergehalt möglich ist, werden große Poren durch eine heterogene Verteilung der Vernetzungsdichte gebildet. Der Einfluß von Art und Menge des Vernetzers sowie der Inertkomponente werden diskutiert. Die Ursache der Bildung von Hydrogelen mit dichter Hüllstruktur wird an mehreren Beispielen erläutert.

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The cryoprotective properties of hydroxyethyl starch investigated by means of differential thermal analysis

Cited by 33 publications

References 14 publications

The Glass Transition Behaviors of Hydroxyethyl Starch Solutions

The Glass Transition Behaviors of Hydroxyethyl Starch Solutions

Cryopreservation of Human Erythrocytes with Hydroxyethyl Starch

Synthese und eigenschaften von polymeren hydrogelen

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