Ultrasensitive detection of microRNA using an array of Au nanowires deposited within the channels of a porous anodized alumina membrane

A new nanopore array/Au electrode was fabricated and applied to the detection of microRNA. The electrode was prepared via alternating current electrodeposition of Au nanowires in the nanopores of a porous anodic alumina membrane (without the need to remove aluminum or any barrier layer). The internal surface of the nanopores was then functionalized with an electrically neutral morpholino with a specially designed sequence. The resulting electrode shows excellent sensitivity and selectivity in detection of the target miRNA-155. The detection limit is 10 aM and the linear range 10 aM–1 nM in aqueous solution and the electrode can be reused in 6 M urea solution. In addition, it shows good linearity (100 aM–0.1 nM) in a serum sample. This new biosensor is expected to enhance miRNA detection in clinical diagnosis.