Universal ratiometric electrochemical biosensing platform based on mesoporous platinum nanocomposite and nicking endonuclease assisted DNA walking strategy.

The occurrence and development of many complex diseases are associated with various molecules, whose contents are rarely in the early stage of the disease. Thus a universal platform for the ultrasensitive detection of multilevel biomarkers should be developed. In this study, we introduced an electrochemical biosensing system based on nicking endonuclease (Nt.BbvCI) assisted DNA walking strategy. We successfully constructed a universal signal-off-on ratiometric electrochemical biosensor for various biomolecules, including small molecules, nucleic acids, and proteins, by progressively optimizing the schematics (schemes 1, 2, and 3). The MB-hairpin probes (MB-HPs) acted as a signal-off probe, and nanocomposites (MPNs@DOX@DNA2) acted as a conventional signal-on probe (scheme 3). With the aid of the MPNs@DOX@DNA2 and Nt.BbvCI assisted DNA walking mechanism, the designed ratiometric electrochemical biosensor showed a high sensitivity and broad detection range. In addition, the proposed method can be utilized to detect diverse targets quantitatively by changing the sequence of aptamers under optimum experimental conditions. Furthermore, it has been widely proved to realize well-accepted signal response in identifying complex samples, thereby resulting in an wide prospect for bioanalysis and clinical diagnosis.