Electrical and magnetic properties of hemozoin nanocrystals

Hemozoin crystals, also known as malaria pigment, are the by-products of hemoglobin degradation by the Plasmodium parasite during its intra-erythrocytic development. Although it is well known that they are responsible for the peculiar paramagnetic behavior of infected red blood cells, their physical properties are not well known. Here, we show that synthetic hemozoin nanocrystals display an insulating and paramagnetic behavior. Conductive atomic force microscopy measurements on crystals dispensed over flat Au films revealed that hemozoin crystals are insulating, with a breakdown field larger than 5 × 10⁷ V m⁻¹. The magnetic susceptibility, measured with a vibrating sample magnetometer, is 4.1 ± 0.6 × 10⁻⁴, compatible with a paramagnetic behavior. These results are confirmed by impedimetric and magnetophoretic measurements on aqueous suspensions of hemozoin crystals.