The Kinetics of β‐Hematin Crystallization Measured by Depolarized Light Scattering

Abstract

Malaria is caused by Plasmodium sp. parasites transmitted by infected female Anopheles sp. mosquitoes. The survival of the parasites in the host relies on detoxifying free heme by biocrystallization into insoluble crystals called hemozoin. This mechanism of self-preservation is targeted by a certain class of antimalarial drugs, which are screened and selected based on their capacity to inhibit the formation of hemozoin crystals. Therefore, experimental techniques capable of accurately characterizing the kinetics of crystal formation are valuable. Relying on the optical anisotropy of hemozoin, the kinetics of β-hematin crystal formation through the statistical analysis of photon counts of dynamic depolarized light scattering (DDLS), in the absence and presence of an antimalarial drug (chloroquine, CQ), is described. It is found that CQ has an impact on both the nucleation and growth of the crystals.

Pulsed Electron-Electron Double Resonance (PELDOR) and Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy in Bioanalysis

“…The DDLS method quantifies depolarization of the scattered light using additional optical components, e.g. as essentially described before (Schubert et al 2015;Rifaie-Graham et al 2018) as well as illustrated by Fig. 6.4.…”

Revising the Formation of β-Hematin Crystals from Hemin in Aqueous-Acetate Medium Containing Chloroquine: Modeling the Kinetics of Crystallization and Characterizing Their Physicochemical Properties

“…The authors did not propose an equation for modeling this kinetic mechanism; however from the reported results it is possible that the Avrami model could explain the results. Rifaie-Graham et al 29 studied the kinetics of β-hematin crystallization by using depolarized light scattering. The authors reported that the formation of β-hematin follows a process of nucleation and growth, in which initially small clusters form until a seed of specific critical size is reached; then the growth occurs.…”