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@INPROCEEDINGS{Heigl:276644,
author = {Heigl, Raimund and Stellbrink, Jörg and Radulescu, Aurel
and Schweins, Ralf and Schrader, Tobias Erich and Richter,
Dieter},
title = {{C}hange of {F}ractal {D}imension during the early stages
of{L}ysozyme {C}rystallization},
reportid = {FZJ-2015-06972},
year = {2015},
abstract = {In this study we focussed on the question of how to grow
crystals as large as possible in light of their use as
samples for neutron protein crystallography. We concentrated
on the early stages of the crystallization process where the
directions are set whether many small crystals grow or few
large ones. We used lysozyme as a model system since it has
been studied well in the past and the phase diagram of its
crystal growth is known. In order to study the crystal
growth process starting from the very beginning we used a
combination of three scattering techniques since the
involved size ranges require a large q-range. Small angle
neutron scattering was used in combination with static light
scattering on the same sample in order to realize this
extended q-range and in order to obtain structural
information on the growing crystal seeds. In situ dynamic
light scattering at the neutron scattering sample cell was
used to obtain an overview of all sizes present in the
crystallisation process. The small angle neutron scattering
technique required a crystallisation in heavy water instead
of normal water. We found that the crystallization
conditions did not differ too much from the ones mentioned
in the literature for light water when using a corrected pD
value of pD=pH+0.4. The crystallization is initiated by
mixing a 60 mg/ml Lysozyme solution with a $6wt\%$ NaCl
acetate buffer solution (both at pD=4.75 and at 298 K) in a
1 :1 ratio. Immediately after mixing, dimers of lysozyme
molecules are formed and the structure factor seen in the
lysozyme stock solution disappears. Under the chosen
conditions we could observe a fractal growth of the crystal
seeds with a change of the fractal dimension from 1.0 to 1.7
in the first 90 min. This can be interpreted as a branched
crystal seed being formed first which grows more in a linear
manner with little branching. Later, the space in between
the branched arms is filled to cross over to a more densely
packed fractal. With these results theoretical models of
crystal growth can be improved. Furthermore, the early
detection of crystal seeds can be used to rapidly change the
crystallization conditions (e. g. temperature) in order to
avoid the production of more crystal seeds.},
month = {Oct},
date = {2015-10-05},
organization = {Neutron Scattering on Nano-Structured
Soft Matter: Synthetic- and
Bio-Materials, Tutzing (Germany), 5 Oct
2015 - 8 Oct 2015},
cin = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
(München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-1-20110106},
pnm = {6215 - Soft Matter, Health and Life Sciences (POF3-621) /
6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6215 / G:(DE-HGF)POF3-6G15 /
G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)KWS2-20140101},
typ = {PUB:(DE-HGF)24},
url = {https://juser.fz-juelich.de/record/276644},
}