Handheld Aptamer-Magnetic Bead-Quantum Dot Sensor for Leishmania

Operational Technologies Corporation (OpTech) has completed a successful Phase I SBIR contract in which 72 new candidate DNA aptamer sequences against Leishmania major were developed and screened by ELISA-like plate assay. Several pilot assays were developed from the highest affinity candidate aptamers using a commercially available handheld and battery-operated fluorometer. In Phase II, OpTech plans to fully develop and deliver to the DoD two or more rapid (15 minute) ultrasensitive one-step plastic-adherent DNA aptamer-magnetic bead (MB) fluorescent sandwich assays (Bruno et al., J. Fluorescence 19:427-435, 2009) for L. major and L. infantum and a visceral leishmaniasis (39 kD kinesin) aptamer assay. In Phase I, this assay format demonstrated detection of Campylobacter and Listeria to<10 cfu/mL and between 10-100 Leishmania promastigotes. OpTech will optimize its lyophilized assay performance with respect to specificity, sensitivity and shelf life of>2 years at 35oC by systematic study of DNA aptamer, magnetic bead, and fluorescent nanoparticle reagent concentrations. OpTech will also evaluate trehalose or other excipient level effects along with innovative vacuum or air-tight packaging of the lyophilized assays. Finally, OpTech will test the assays against various species of live Leishmania and compare to gold standard ELISA and PCR assays.