First Direct Observation of Impurity Effects on the Growth Rate of Tetragonal Lysozyme Crystals under Microgravity as Measured by Interferometry
Suzuki, Yoshihisa, et al. (2015). "First Direct Observation of Impurity Effects on the Growth Rate of Tetragonal Lysozyme Crystals under Microgravity as Measured by Interferometry." Crystal Growth & Design 15 10: 4787-4794
The normal growth rates R and apparent step velocities (lateral growth rates of a spiral hillock) V of tetragonal hen egg-white lysozyme (HEWL) crystals were for the first time measured by Michelson interferometry in the international space station (as part of the NanoStep project) using commercialized HEWL samples containing 1.5% impurities. A significant increase in V under microgravity was confirmed compared to step velocities Vstep on the ground, while a decrease in R was also confirmed compared to that in the purified solution under microgravity as expected. Because of exact measurement of growth rates, kinetic analyses of R were conducted as a function of supersaturation, σ (σ ≡ ln(C/Ce), where C is the concentration; Ce is the solubility), using a spiral growth model and a two-dimensional (2D) nucleation growth model. For both models over a wide range of σ, R in the impure solution was significantly lower than that in the purified solution. The degree of the suppression of impurity effects was also evaluated using the difference in Vp and Vi, where Vp is the apparent step velocity in the purified solution, and Vi is that in the impure solution. The difference between Vp and Vi was smaller than the difference in step velocities on the ground, Vstep,p and Vstep,i, where Vstep,p is the step velocity in the purified solution, and Vstep,i is the step velocity in the impure solution.
ISSN: 1528-7483 1528-7505