title: 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.
authors.affiliation: 1] BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. [2].
authors.forename: Weng Kung
authors.initials: WK
authors.lastname: Peng
authors.affiliation: 1] BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. [2] School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore. [3].
authors.forename: Tian Fook
authors.initials: TF
authors.lastname: Kong
authors.affiliation: 1] School of Biological Sciences, Nanyang Technological University, Singapore. [2] Infectious Diseases IRG, SMART Centre, Singapore. [3].
authors.forename: Chee Sheng
authors.identifier: 0000000264742404
authors.initials: CS
authors.lastname: Ng
authors.affiliation: BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore.
authors.forename: Lan
authors.initials: L
authors.lastname: Chen
authors.affiliation: BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore.
authors.forename: Yongxue
authors.initials: Y
authors.lastname: Huang
authors.affiliation: 1] BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. [2].
authors.forename: Ali Asgar S
authors.initials: AA
authors.lastname: Bhagat
authors.affiliation: 1] BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. [2] School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore. [3].
authors.forename: Nam-Trung
authors.identifier: 0000000336265361
authors.initials: NT
authors.lastname: Nguyen
authors.affiliation: 1] School of Biological Sciences, Nanyang Technological University, Singapore. [2] Infectious Diseases IRG, SMART Centre, Singapore.
authors.forename: Peter Rainer
authors.initials: PR
authors.lastname: Preiser
authors.affiliation: 1] BioSystems &Micromechanics Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. [2] Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. [3] Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: Jongyoon
authors.initials: J
authors.lastname: Han
mesh_terms: D000818:Animals; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D008280:Magnetics; D008288:Malaria / Q000175:diagnosis* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D010961:Plasmodium / Q000145:classification / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013045:Species Specificity