Micromagnetic resonance relaxometry for rapid label-free malaria diagnosis

Abstract

We report a new technique for sensitive, quantitative and rapid detection of Plasmodium spp.-infected red blood cells (RBCs) by means of magnetic resonance relaxometry (MRR). During the intraerythrocytic cycle, malaria parasites metabolize large amounts of cellular hemoglobin and convert it into hemozoin crystallites. We exploit the relatively large paramagnetic susceptibility of these hemozoin particles, which induce substantial changes in the transverse relaxation rate of proton nuclear magnetic resonance of RBCs, to infer the 'parasite load' in blood. Using an inexpensive benchtop 0.5-Tesla MRR system, we show that with minimal sample preparatory steps and without any chemical or immunolabeling, a parasitemia level of fewer than ten parasites per microliter in a volume below 10 μl of whole blood is detected in a few minutes. We demonstrate this method both for cultured Plasmodium falciparum parasites and in vivo with Plasmodium berghei-infected mice.

Malaria diagnosis for malaria elimination

“…A number of recent studies have reported on strategies to exploit physical and/or electromagnetic features of hemozoin crystals to detect infection by malaria parasites [54,[80][81][82][83][84][85][86]. Generally, the LOD of these methods is between 1 and 30 iRBCs/ml and, therefore, not as sensitive as NAA strategies.…”

Novel techniques and future directions in molecular diagnosis of malaria in resource-limited settings

“…The technologies under development take advantage of unique properties of hemozoin such as its optical properties, hemozoin crystals scatter and depolarize light in a unique way and differently than red blood cells; and its magnetic properties, it is slightly magnetic due to its derivation from iron-containing hemoglobin [11]. Several novel platforms such as magneto-optical detection, magnetic resonance relaxometry and biosensing [36][37][38] have been explored to detect the hemozoin pigment in Plasmodium genus infections. Transdermal laser detection of hemozoingenerated vapor nanobubbles has also been reported recently [39].…”

Recently Developed New, Sensitive, Time-Effective and Cost-Effective Diagnostic Tests of Malaria

“…Presently, the most reliable malaria diagnosis depends on PCR tests which also identify the Plasmodium species causal of malaria. Recently, Juul et al (2012) and Peng et al (2014) have respectively developed the quantitative Plasmodium detection procedures. Rolling-circle Enhanced Enzyme Activity Detection (REEAD)-on-chip test and the Micromagnetic resonance Relaxometry (MMR) malaria test.…”