Figure 7.

(a) Schematic of an electrochemical genosensor based on cobalt porphyrin with an efficient “signal-off” detection of the target sequence in the femtomolar range.⁶¹ (b) DNA bundle consisting of six DNA helices with two porphyrins as lipophilic anchors to create artificial nanopores with a 2 nm inner pore diameter, Reprinted by permission of John Wiley & Sons, Inc. from ref (63). (c) A minimal porphyrin–DNA pore where the current is induced through a flow of ions along the DNA backbone (left).⁶⁴ This is compared to a two-porphyrin-DNA with longer linkers and elongated distance between the porphyrin attachment sites (right), embedding the porphyrins in the membrane while keeping the underlying DNA scaffold in the aqueous environment. Reproduced from ref (66) with permission from the Royal Society of Chemistry.