Pd nanoparticles-DNA layered nanoreticulation biosensor based on target-catalytic hairpin assembly for ultrasensitive and selective biosensing of microRNA-21

Herein, a Pd nanoparticles-DNA layered nanoreticulation (Pd NPs-DNA LNR) sensor was assembled to a graphene oxide (GO)-modified electrode by catalytic hairpin assembly (CHA) and a self-assembly process. In this process, GO was modified on the electrode surface to provide -COOH sites for DNA bonding. Moreover, with the CHA circular amplification strategy, many single DNA1 were exposed to be able to be bound with Pd-DNA2 for the formation of the Pd NPs-DNA LNR, which enabled the ultrasensitive detection of microRNA-21 (miR-21) with a low limit of detection 63.1 aM. This strategy combines the amplification technology of CHA and Pd NPs-DNA LNR with Pd NPs. Such a layered nanoreticulation material can support abundant Pd NPs to avoid aggregation and obtain enhanced electrochemical signals. Significantly, this method can be successfully applied in tumor cell lysates and provides a neoteric channel for early disease diagnosis.