On‐chip magnetophoretic capture in a model of malaria‐infected red blood cells

The search for new rapid diagnostic tests for malaria is a priority for developing anefficient strategy to fight this endemic disease, which affects more than 3 billionpeople worldwide. In this study, we characterize systematically an easy‐to‐operatelab‐on‐chip, designed for the magnetophoretic capture of malaria‐infected red bloodcells (RBCs). The method relies on the positive magnetic susceptibility of infectedRBCs with respect to blood plasma. A matrix of nickel posts fabricated in a siliconchip placed face down is aimed at attracting infected cells, while healthy cells se-diment on a glass slide under the action of gravity. Using a model of infected RBCs,that is, erythrocytes with methemoglobin, we obtained a capture efficiency of about70% after 10 min in static conditions. By proper agitation, the capture efficiencyreached 85% after just 5 min. Sample preparation requires only a 1:10 volume di-lution of whole blood, previously treated with heparin, in a phosphate‐bufferedsolution. Nonspecific attraction of untreated RBCs was not observed in the sametime interval.