P.W.G. Poodt, M.C.R. Heijna, A. Schouten,
P. Gros, W.J.P. van Enckevort, E. Vlieg,
Simple geometry
for diffusion limited protein crystal growth: harnessing gravity to
suppress convection,
Cryst. Growth Des. 9 (2009) 885-888
Abstract
A new upside-down geometry is proposed to achieve the beneficial
effects of microgravity crystal growth by making use of buoyant forces
instead of compensating for them. We show by growth experiments on
sodium chlorate and lysozyme that crystal growth in an upside-down
geometry leads to the formation of a buoyancy assisted depletion zone
where convection is suppressed. The effects on growth rate and
morphology that are observed are all indicative of diffusion limited
growth, just as would happen in the absence of gravity. The optical
quality of the lysozyme crystals clearly improved, but no effects of
the growth method on X-ray diffraction quality could be observed. The
simplicity of the growth geometry offers the possibility to perform
large scale protein crystal growth experiments under microgravity-like
conditions, without the requirement of compensating for gravity.