Malaria quantitative POC testing using magnetic particles, a paper microfluidic device and a hand-held fluorescence reader

A point-of-care (POC) device is reported for highly sensitive and selective detection of Plasmodium falciparum lactate dehydrogenase (Pf-LDH), a biomarker of malaria infection, based on a single-step magneto-immunoassay, a single-use microfluidic paper device and a customized hand-held fluorescence reader. The single-step magneto -immunoassay consists in a single 5-min incubation of immuno-modified magnetic particles (c-MAb-MPs), bio-tinylated detection antibody (bd-MAb), and an enzymatic signal amplifier (Poly-HRP). After on-chip MP con-centration and washing, signal generation is achieved by adding a fluorescent enzymatic substrate (QuantaRed). Fluorescence signal is measured using a low-cost customized, portable, and sensible fluorescent detector. The POC affords quantitative Pf-LDH detection in <20 min, with a detection limit of 0.92 ng mL-1 (equivalent to 4.6 parasites mu L-1). Furthermore, Pf-LDH quantitation in clinical samples correlates with that provided by the reference ELISA, is more sensitive than a commercial rapid diagnostic test (RDT) and entails little user inter-vention. These results show that fluorescent paper-based microfluidic devices can be exploited to simplify magneto-immunoassay handling, taking this type of test closer to the requirements of POC testing.

Automated summary

A point-of-care device for sensitive and selective detection of malaria infection biomarker using a single-step magneto-immunoassay has been reported, providing quantitative results in less than 20 minutes with high sensitivity. This device shows great potential to simplify testing procedures and improve detection accuracy.