Enhancing the Sensitivity of Photoelectrochemical DNA Biosensing Using Plasmonic DNA Barcodes and Differential Signal Readout.

Photoelectrochemical biosensors hold great promise for sensitive bioanalysis; however, similar to their electrochemical analogues, they are highly affected by the variable backgrounds caused by biological matrices. We developed a new PEC biosensing strategy that uses differential signal generation, combining signals from two separate but correlated binding events on the biosensor, for improving the limit-of-detection, sensitivity, and specificity of PEC DNA biosensors in biological samples. In this assay, the binding of unlabeled target DNA is followed by the capture of a signal amplification barcode featuring a plasmonic nanoparticle. The interaction of the plasmonic barcode with the semiconductive building blocks of the biosensor results in significant signal amplification, and together with differential signal processing enhances the limit of detection and sensitivity of the assay by up to 15- and three-fold, respectively, compared to the previously-used PEC assays with a single binding event, demonstrating a limit of detection of 3 fM.