_1 3
FREEZE-DRYÏNG
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20',
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—50
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remununr
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FÏGURE 7. Thermal analysis of 1 % dimethyl sulphoxide in 0.9 % sodium chloride. The sudden increase in
resistance on thawing which occurs immediately after an exothermic reaction suggests the crystalsation of a
metastable glass. The decrease in resistance and endothemc reaction which follow correspond to the thaw—
ing of such a crystalh‘ne compound (Greaves & Davies, 1965).
stated that in the case of cells stored in dimethyl sulphoxide at —— 70°C the effective concentration ofthe protective is 55 % and that the cells are present ina liquid phase. By using
very simple experiments the author has recently been able to show that at such concentra—
tions and temperatures the Visoosity of this liquid phase is extremely high and as the temperature is further reduced this sympy mass progressively hardensinto a «glass—like compound which is quite transparent and which can be shatteredlike a window pane.
It
would therefore appear that when cell suspensions in protective media are frozen and stored
at low temperature the cells are present…in glass—like channels:tràpped between the ice
crystals.
«
…
-
…
‘.…
.:
=
&
…
-
Such a theory of glass formation
compounds “would seem to provide a
suitable common …explanation to the diverse theories lof limitation --ofæs alt concentration and
prevention of
However, in the …casé‘opievenüonbf salt concentra—
tion;such a theory could only be: cômeæly…justied if sin factfthe îadditiVe‘ in question was
ableto gain access to the; inside: of the
In this respect
Of int«àres‘t=tondiscuss some
experiments which we
out: using livingcells; ‘
-
…
»,
"f
..
experiments in: the study of: the
; of freeZiiig
yeast:;SâeèharômÿceS
cerevisiaeÿ(as used by… Mazur; 1960)»showed that, -witha slow
IFC
min; toi a temperature of —…35‘$Ç followed
a… rapid
even when the
çWats*suspfäde‘d
FREEZE-DRYÏNG
'
1°
.
1M__
'
f
SOUK
; zoo
=
__
.
==
"
-
. ;
‘.
1
:
,
'
IOO' …
3
t
'
«
“:
_
:
_
,
'
2
se "
"
VB
.
:;
,
-
.
=;
—
a
.
;
20',
-ul°°
-90
-30
-7
—60
—50
-40'
—30
-20
-10
°
remununr
°c
FÏGURE 7. Thermal analysis of 1 % dimethyl sulphoxide in 0.9 % sodium chloride. The sudden increase in
resistance on thawing which occurs immediately after an exothermic reaction suggests the crystalsation of a
metastable glass. The decrease in resistance and endothemc reaction which follow correspond to the thaw—
ing of such a crystalh‘ne compound (Greaves & Davies, 1965).
stated that in the case of cells stored in dimethyl sulphoxide at —— 70°C the effective concentration ofthe protective is 55 % and that the cells are present ina liquid phase. By using
very simple experiments the author has recently been able to show that at such concentra—
tions and temperatures the Visoosity of this liquid phase is extremely high and as the temperature is further reduced this sympy mass progressively hardensinto a «glass—like compound which is quite transparent and which can be shatteredlike a window pane.
It
would therefore appear that when cell suspensions in protective media are frozen and stored
at low temperature the cells are present…in glass—like channels:tràpped between the ice
crystals.
«
…
-
…
‘.…
.:
=
&
…
-
Such a theory of glass formation
compounds “would seem to provide a
suitable common …explanation to the diverse theories lof limitation --ofæs alt concentration and
prevention of
However, in the …casé‘opievenüonbf salt concentra—
tion;such a theory could only be: cômeæly…justied if sin factfthe îadditiVe‘ in question was
ableto gain access to the; inside: of the
In this respect
Of int«àres‘t=tondiscuss some
experiments which we
out: using livingcells; ‘
-
…
»,
"f
..
experiments in: the study of: the
; of freeZiiig
yeast:;SâeèharômÿceS
cerevisiaeÿ(as used by… Mazur; 1960)»showed that, -witha slow
IFC
min; toi a temperature of —…35‘$Ç followed
a… rapid
even when the
çWats*suspfäde‘d