Signal amplification in electrochemical DNA biosensors using target-capturing DNA origami tiles

Electrochemical DNA (e-DNA) biosensors are feasible tools for disease monitoring, with their ability to translate hybridization events between a desired nucleic acid target and a functionalized transducer, into recordable electrical signals. Such an approach provides a powerful method of sample analysis, with a strong potential to generate a rapid time to result in response to low analyte concentrations. Here we report a strategy for the amplification of electrochemical signals associated with DNA hybridization, by harnessing the programmability of the DNA origami method to construct a sandwich assay to boost charge transfer resistance (RCT) associated with target detection. This allowed for an improvement in sensor limit of detection by two-orders of magnitude compared to a conventional label-free e-DNA biosensor design and linearity for target concentrations between 10 pM – 1 nM without the requirement for probe labeling, or enzymatic support. Additionally, this sensor design proved capable of achieving a high degree of strand selectivity in a challenging DNA-rich environment. This approach serves as a practical method for addressing strict sensitivity requirements necessary for a low cost point-of-care (PoC) device.