A highly sensitive aptasensor towards Plasmodium lactate dehydrogenase for the diagnosis of malaria

▸ The ssDNA aptamers for Plasmodium lactate dehydrogenase (pLDH) were discovered. ▸ We designed the pLDH aptasensor using electrochemical impedance spectroscopy. ▸ Both PvLDH and PfLDH were selectively detected with a detection limit of 1pM. ▸ The aptasensor clearly identified malaria-positive blood samples with high sensitivity. Finding a highly sensitive diagnostic technique for malaria has challenged scientists for the last century. In the present study, we identified versatile single-strand DNA aptamers for Plasmodium lactate dehydrogenase (pLDH), a biomarker for malaria, via the Systematic Evolution of Ligands by EXponential enrichment (SELEX). The pLDH aptamers selectively bound to the target proteins with high sensitivity (Kd=16.8–49.6nM). The selected aptamers were characterized using an electrophoretic mobility shift assay, a quartz crystal microbalance, a fluorescence assay, and circular dichroism spectroscopy. We also designed a simple aptasensor using electrochemical impedance spectroscopy; both Plasmodium vivax LDH and Plasmodium falciparum LDH were selectively detected with a detection limit of 1pM. Furthermore, the pLDH aptasensor clearly distinguished between malaria-positive blood samples of two major species (P. vivax and P. falciparum) and a negative control, indicating that it may be a useful tool for the diagnosis, monitoring, and surveillance of malaria.