A universal electrochemical biosensor using nick-HCR nanostructure as molecular gate of nanochannel for detecting Chromium (III) ions and microRNA

Solid-state nanochannels demonstrating excellent mechanical properties and chemical stability combined with programmable DNA provide an opportunity to control on-demand ion transport. However, poor functionalization of the nanochannels limits the types of detected targets, as well as its universality in the sensing field. To solve these issues, a universal nanochannel sensing platform was developed by employing a nick hybridization chain reaction (nHCR) nanostructure as a molecular gate, which could generally respond to the universal sequence Y. Metal ion-dependent DNAzyme cleavage was used to transfer the chromium(III) (Cr3+) ions into nucleic acid X, which was further amplified and converted into universal sequence Y. Upon adding sequence Y into the nHCR nanostructure-functionalized nanochannel, the disassembly of the nHCR molecular gate turned on the ionic current signal inside the nanochannel. The ON–OFF ratio displayed a linear relationship with the Cr3+ concentration in the range from 200 fM to 20 n...