Synergistic signal amplification of a 3D Dual-Core DNA nanomachine and PCNs@AuPdCe hybrid nanozymes for ultrasensitive electrochemical detection of Cell-free DNA

The potential for early cancer detection through cell-free DNA (cfDNA) analysis is hindered by the low abundance and susceptibility to chemical damage of cfDNA, presenting a formidable challenge for precision analysis. In this study, we introduce an innovative electrochemical biosensor that leverages a three-dimensional (3D) dual-core DNA nanomachine driven by exonuclease III (EXO III) and trimetallic-deposited porous coordination network-224 hybrid nanozymes (PCNs@AuPdCe). The DNA nanomachine is designed with target cfDNA and 8-legged polyamidoamine-ssDNA (octopus-like) as dual dynamic cores, while magnetic beads serve as the 3D orbit, enabling highly stable cascade amplification from 1 to 8 to N. The newly synthesized PCNs@AuPdCe exhibits remarkable superoxide dismutase-, catalase-, and peroxidase-like activity and serves as a signal tag. The synergistic amplification resulting from the dual-core DNA nanomachine and PCNs@AuPdCe enables the biosensor to detect cfDNA levels as low as "a" M with a broad detection range from 1 fM to 1 nM. Analysis of real plasma samples demonstrates the robust anti-interference ability and promising clinical applications of the biosensor. Therefore, the construction of this electrochemical biosensor is of great significance to promote the development of in vitro diagnostic technology for early cancer screening.