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Enhancing malaria diagnosis through microfluidic cell enrichment and magnetic resonance relaxometry detection.

Kong TF, Ye W, Peng WK, Hou HW - Sci Rep (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore [2] BioSystems and Micromechanics (BioSyM) IRG, Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 Create Way, #03 Enterprise Wing, Singapore.

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.

No MeSH data available.


Related in: MedlinePlus

RBC R2 measurements.(a) Weekly R2 measurement of a healthy blood sample for up to three weeks of post storage. As the hRBCs age, the R2 value increased as much as 16.7% from day two to day 21. (b) The normalized spin-down R2 values of hRBCs and iRBCs for the blood samples collected at inlet, middle, and side outlets. However, for hRBCs, the side outlet R2 value is significantly higher than the inlet and middle R2. For healthy blood sample, the margination device also separates the stiffer old RBCs from the more flexible young RBCs. When the hRBCs are spiked with the presence of 0.0005% iRBCs, the R2 value of the side outlet increases further since the iRBCs are marginated towards the sidewalls.
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f4: RBC R2 measurements.(a) Weekly R2 measurement of a healthy blood sample for up to three weeks of post storage. As the hRBCs age, the R2 value increased as much as 16.7% from day two to day 21. (b) The normalized spin-down R2 values of hRBCs and iRBCs for the blood samples collected at inlet, middle, and side outlets. However, for hRBCs, the side outlet R2 value is significantly higher than the inlet and middle R2. For healthy blood sample, the margination device also separates the stiffer old RBCs from the more flexible young RBCs. When the hRBCs are spiked with the presence of 0.0005% iRBCs, the R2 value of the side outlet increases further since the iRBCs are marginated towards the sidewalls.

Mentions: Recently, we have shown that micro magnetic resonance relaxometry can be used as a new approach for malaria diagnostics20. The malaria infected iRBCs have higher transverse relaxation rate, R2 than the healthy hRBCs due to the presence of paramagnetic hemozoin crystallites in the infected blood20. These paramagnetic crystallites increase the bulk magnetic susceptibility of the iRBCs and induce a considerable increase in the R2 relaxation rate. Hence, the detection of the subtle increase in the R2 due to the presence of malaria parasites forms the basis of MRR malaria detection. However, MRR detection method measures the absolute R2 value of the blood sample instead of a relative change in the R2 value. The healthy absolute R2 value varies from individual to individual depending on numerous factors such as age, diet, genetic variation, and hematocrit number, and methemoglobin content. Furthermore, the R2 value of hRBCs increases with the number of post storage days when stored under hypothermic condition at 4 °C (Fig. 4(a)). The R2 value of that healthy blood sample increased from 6.80 ± 0.04 s−1 on day two to 7.94 ± 0.13 s−1 on day 21, an increment of 16.7%. Since the R2 value of the hRBCs increases as the RBCs age, establishing a universal healthy baseline R2 value for all individuals is rather impractical. Therefore, the malaria detection method based on the measurement of absolute R2 value needs to overcome the problem of the variation in the healthy baseline to be fully effective.


Enhancing malaria diagnosis through microfluidic cell enrichment and magnetic resonance relaxometry detection.

Kong TF, Ye W, Peng WK, Hou HW - Sci Rep (2015)

RBC R2 measurements.(a) Weekly R2 measurement of a healthy blood sample for up to three weeks of post storage. As the hRBCs age, the R2 value increased as much as 16.7% from day two to day 21. (b) The normalized spin-down R2 values of hRBCs and iRBCs for the blood samples collected at inlet, middle, and side outlets. However, for hRBCs, the side outlet R2 value is significantly higher than the inlet and middle R2. For healthy blood sample, the margination device also separates the stiffer old RBCs from the more flexible young RBCs. When the hRBCs are spiked with the presence of 0.0005% iRBCs, the R2 value of the side outlet increases further since the iRBCs are marginated towards the sidewalls.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4469967&req=5

f4: RBC R2 measurements.(a) Weekly R2 measurement of a healthy blood sample for up to three weeks of post storage. As the hRBCs age, the R2 value increased as much as 16.7% from day two to day 21. (b) The normalized spin-down R2 values of hRBCs and iRBCs for the blood samples collected at inlet, middle, and side outlets. However, for hRBCs, the side outlet R2 value is significantly higher than the inlet and middle R2. For healthy blood sample, the margination device also separates the stiffer old RBCs from the more flexible young RBCs. When the hRBCs are spiked with the presence of 0.0005% iRBCs, the R2 value of the side outlet increases further since the iRBCs are marginated towards the sidewalls.
Mentions: Recently, we have shown that micro magnetic resonance relaxometry can be used as a new approach for malaria diagnostics20. The malaria infected iRBCs have higher transverse relaxation rate, R2 than the healthy hRBCs due to the presence of paramagnetic hemozoin crystallites in the infected blood20. These paramagnetic crystallites increase the bulk magnetic susceptibility of the iRBCs and induce a considerable increase in the R2 relaxation rate. Hence, the detection of the subtle increase in the R2 due to the presence of malaria parasites forms the basis of MRR malaria detection. However, MRR detection method measures the absolute R2 value of the blood sample instead of a relative change in the R2 value. The healthy absolute R2 value varies from individual to individual depending on numerous factors such as age, diet, genetic variation, and hematocrit number, and methemoglobin content. Furthermore, the R2 value of hRBCs increases with the number of post storage days when stored under hypothermic condition at 4 °C (Fig. 4(a)). The R2 value of that healthy blood sample increased from 6.80 ± 0.04 s−1 on day two to 7.94 ± 0.13 s−1 on day 21, an increment of 16.7%. Since the R2 value of the hRBCs increases as the RBCs age, establishing a universal healthy baseline R2 value for all individuals is rather impractical. Therefore, the malaria detection method based on the measurement of absolute R2 value needs to overcome the problem of the variation in the healthy baseline to be fully effective.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore [2] BioSystems and Micromechanics (BioSyM) IRG, Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 Create Way, #03 Enterprise Wing, Singapore.

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.

No MeSH data available.


Related in: MedlinePlus