Paper diagnostic device for quantitative electrochemical detection of ricin at picomolar levels

We report a paper-based assay platform for detection of ricin a chain. The paper platform is assembled by simple origami paper folding. The sensor is based on quantitative, electrochemical detection of silver nanoparticle labels linked to a magnetic microbead support via a ricin immunosandwich. Importantly, ricin was detected at concentrations as low as 34 pM. Additionally, the assay is robust, even in the presence of 100-fold excess hoax materials. Finally, the device is easily remediated after use by incineration. The cost of the device, not including reagents, is just $0.30. The total assay time, including formation of the immunosandwich, is 9.5 min.