Fluorescent Nanoparticle-Aptamer-Magnetic Bead Sensor for Bioterrorism Detection in Water

Some bioterrorism agents cause disease at very low infective doses and their presence can be masked by the environment. Therefore, ultrasensitive detection is required for homeland defense applications. In this Phase I research project, Operational Technologies Corporation (OpTech) proposes to couple DNA aptamers made by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process to commercially available fluorescent nanoparticles (NPs, composed of chelated europium in polystyrene). OpTech will demonstrate aptamer-NP-mediated detection of a bacterial, viral, and toxin simulant at low levels. Fluorescent NPs are nanometer-sized plastic and metallic "beads" that endow superior sensitivity in clinical assays (up to zeptomolar [10-21] detection limits). OpTech also will couple the DNA aptamers to magnetic microbeads and demonstrate magnetic separation and purification of the bioterrorism agent simulants from natural water samples in conjunction with aptamer-fluorescent NP detection (i.e., sandwich bead assay). In Phase II, OpTech will design and build a prototype compact or handheld fluorescence reader. The reader will be equipped with a special magnetically assisted cartridge and employ simple magnetic microbead aptamer-fluorescent NP sandwich assays to probe, capture, and concentrate bioterrorism agents from environmental samples prior to analysis, thereby pushing the limits of sensitivity to unprecedented low levels, even in "dirty" water samples. There is a great demand for ultrasensitive assays and instrumentation in the clinical diagnostic, water monitoring, and food industries. The marriage of well-established magnetic microbead assays, such as those marketed by Dynal, Inc., and IGEN International, Inc., with nascent NP fluorescence assays, should produce incredibly sensitive and useful assays as well as sensors for these industries.