An aptamer-based sensor for the detection of antimalarial drugs

Artemisinin-based combination therapies (ACTs) have begun to fail as first-line therapies for the treatment of Plasmodium falciparum malaria in Southeast Asia. Preventing the further spread of drug-resistant parasites is a top priority for global malaria elimination campaigns. A low-cost, field-based assay to detect slow clearing ACT compounds from patient samples could allow for improved tracking of antimalarial drug use, monitoring of treatment adherence, and evaluation of therapeutic efficacy and resistance. It could also provide sensitive detection of active components in assessments of tablet quality. This research reports the development of a low-cost, rapid, fluorescent sensor for the specific detection of piperaquine and mefloquine. In order to do this, DNA aptamers were identified that bind and differentiate between small molecule partner drugs. These aptamers were selected from a library of single-stranded DNA molecules for their selectivity and binding affinity. Following their isolation by a capture-SELEX method, a structure-switching aptamer fluorescent sensor was developed. The sensor performance was optimized for the detection of drug from crushed tablets and from human serum, resulting in two fluorescent sensing platforms. The sensors were evaluated for their sensitivity and specificity in relevant sample matrices and the serum sensor was validated against an LC-MS gold standard drug detection method. Feedback from potential assay end-users was collected to inform the assay development and it is believed that these aptamer sensors will be useful tools for monitoring antimalarial drug quality and studying antimalarial drug use.