Figure 7.

Schematic illustration of formation of metalized wires from stretched rolling circle amplification products to generate an electrical signal. A padlock probe, whose ends have been designed to hybridize head-to-tail on a target sequence, is hybridized and ligated to a self-assembled monolayer (SAM) of oligonucleotides containing the target sequence and poly(ethylene glycol) (PEG) alkane backfiller on a gold electrode (A–C); (D) This circle is then used for RCA, creating a long single-stranded product on the electrode; (E) Oligonucleotide-functionalized gold nanoparticles are then hybridized to the product; (F) With the aid of these particles, the single-stranded DNA threads are metalized using either a silver or gold salt solution to form metal wires. Reprinted with permission from [104]. Copyright 2014, American Chemical Society.