Abstract
Despite significant advancements over the years, there remains an urgent need for low cost diagnostic approaches that allow for rapid, reliable and sensitive detection of malaria parasites in clinical samples. Our previous work has shown that magnetic resonance relaxometry (MRR) is a potentially highly sensitive tool for malaria diagnosis. A key challenge for making MRR based malaria diagnostics suitable for clinical testing is the fact that MRR baseline fluctuation exists between individuals, making it difficult to detect low level parasitemia. To overcome this problem, it is important to establish the MRR baseline of each individual while having the ability to reliably determine any changes that are caused by the infection of malaria parasite. Here we show that an approach that combines the use of microfluidic cell enrichment with a saponin lysis before MRR detection can overcome these challenges and provide the basis for a highly sensitive and reliable diagnostic approach of malaria parasites. Importantly, as little as 0.0005% of ring stage parasites can be detected reliably, making this ideally suited for the detection of malaria parasites in peripheral blood obtained from patients. The approaches used here are envisaged to provide a new malaria diagnosis solution in the near future.
Highlights
We develop a malaria diagnosis protocol that combines the use of microfluidics for the separation of infected red blood cells (iRBCs) and magnetic resonance relaxometry (MRR) system for the rapid, label-free detection of malaria parasites
The efficient enrichment of iRBC would be of significant benefit for the subsequent diagnostic of malaria, in cases of very low parasitemia levels
We have successfully developed a malaria diagnosis technique that combines the use of microfluidics for the separation of iRBCs and MRR system for a rapid, label-free detection of malaria parasites
Summary
The major challenges in current clinical malaria diagnostics are in obtaining a sensitive, robust, fast, and inexpensive measurement from patients’ blood samples. The miniaturization of magnetic resonance relaxometry (MRR) systems has been attracting considerable interest in recent years due to the promising applications in disease biomarker detection, point-of-care diagnosis, and cancer screening by measuring the transverse relaxation rate, R2 of proton present in the bio-samples[14,15,16,17]. Ribaut et al.[23] and Zimmerman et al.[24] concentrate and purify iRBCs through magnetic columns (MACS) and magnetic deposition microscopy (MDM), respectively Both techniques have a serious limitation in that they were unable to separate ring stage iRBCs, which is important for the human P. falciparum malaria diagnosis. In contrast to the DEP or MDM methods, microfluidic margination offers the convenience of not needing external electrical and magnetic fields for iRBCs separation
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