Freezing surface-induced

Chang, B.S. Kendrick, B.S. Carptenter, J.F. Surface-induced denaturation of proteins during freezing and its inhibition by surfactants. J. Pharm. Sci. 1996,85,1325-1330. 

Figure 4. The relationship between temperature, water content, and stability (after Franks, F.f In a dilute aqueous suspension, a biochemically active molecule is structural stabile but is vulnerable to a wide range of environmental degradative forces such as hydrolysis, oxidation and racemization. In a surface immobilized or dehydrated state, a biochemically active molecule achieves peater kinetic stability at a cost of thermodynamic instability. From a dilute state (A) through supersaturation (S) with progressive water loss on the way to a solid glassy state (B), a biochemcially active molecule passes through a thermodynamically defined (entropic loss of water and enthalpy of adsorption) transition zone (stippled) where irreversible conformational changes may occur. We have observed that the disaccharides used to fabricate Aquasomes appear to stabilize biochemically active molecules in this zone during surface-induced dehydration. The dashed line represent the freeze-drying pathway between the eutectic point and Tg.

Pluis, B., Denier van der Gon, A. W. and van der Veen J. F. (1990). Surface-induced melting and freezing. I. Medium-energy ion scattering investigation of the melting of Ph hkl] crystal faces. Surface Science, Vol. 239, p.265-281, ISSN 00396028... 

B. Pluis, D. Frenkel, J.F. Vanderveen, Surface-induced melting and freezing IL A semi-empirical landau-type model. Surf. Sci. 239(3), 282-300 (1990)... 

The implication for experiments is clearly that crystallization of suspensions of hard-sphere colloids should proceed heterogeneously, whenever a sufficiently flat surface is available. Yet, somewhat surprisingly, there are, to our knowledge, no systematic experimental observations of surface-induced freezing in hard sphere colloids, even though most bulk crystallization studies are performed in contain-... 

Although fusion between SFV and the plasma membrane normally does not occur, cell surface-bound viruses can be induced to fuse simply by decreasing the extracellular pH below 6 for a few seconds (White et al., 1980 Vaananen et al., 1981). As a result of its fusion activity SFV can hemolyze red blood cells at pH 5.8 (VaanSnen and Kaari inen, 1979, 1980). However, the lysis occurs only with virus damaged by freezing and thawing. Cells can also be made to fuse with each other using SFV at low pH (White et al., 1981). 

Cryoinjury to the specimen is caused directly by extra- or intracellular ice crystal formation as well as by ice-induced solution effects during cryopreservation. Ice crystals seriously deform cell components. Another disadvantage of the formation of ice crystals near the specimen surface is slowing the cooling rate in areas below the surface because their thermal conductivity is about half that of solid water in a noncrystalline state. Furthermore, ice crystal formation is accompanied by the generation of latent heat, which also slows down the freezing rate. 

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