Richard M. Crooks, PhD, Department of Chemistry, UT Austin
November 20, 2014 6 pm (Food starting at 5:30 pm)
Blum Hall B100
Detection of toxins is of particular importance because near real-time detection is essential in cases of imminent threat and because toxins can be modified or otherwise disguised while remaining active. The objective of this project is the creation of new, low-cost, appropriately sensitive paper diagnostic devices for the electrochemical detection of biological weapons. To satisfy this objective, we initiated development of a quantitative ricin sensor using a magnetic microbead supported silver nanoparticle (AgNP) metalloimmunoassay to probe the ricin A chain protein. The sensor integrates picomolar affinity antibodies with our easily handled, but sophisticated, electrochemical detection platform: the oSlip. The oSlip incorporates two simple, but effective, preconcentration steps. The first involves magnetic preconcentration of AgNP labels at a working electrode, followed by the spontaneous oxidation of these labels in the presence of a chemical oxidant stored on the device. Importantly, this oxidizing agent is delivered into the channel at a specific time and location by simply slipping a moveable piece of paper. The resulting Ag ions are then electrodeposited onto the working electrode (the second preconcentration step). Oxidation of this Ag layer leads to detection of the AgNP-labeled target. We have demonstrated quantitative electrochemical detection of ricn A chain at a LOD of 78 pM by means of fast (3.5 minutes) and non-enzymatic signal amplification. Importantly, the custom antibodies can bind to both glycosylated and recombinant ricin, allowing for the detection of genetically modified toxins. This project is sponsored by the Defense Threat Reduction Agency (Contract Number HDTRA-1-13-1-0031).