Copper nanocluster based cascade amplified DNA electrochemical detection combining with bio-barcode assay and surface-initiated enzyme polymerization.

Early cancer diagnosis is paramount for enhancing treatment efficacy, extending patient survival, and improving the quality of life. We developed a highly sensitive electrochemical biosensor for the detection of target DNA (tDNA) associated with gastric cancer. This advancement integrates dual signal amplification strategies: bio-barcode amplification (BCA) and surface-initiated enzyme polymerization (SIEP), with copper nanoclusters (CuNCs) serving as signal labels. Silica nanoparticles (SiO) were covalently linked with polythymine (poly T) and complementary DNA to create bio-barcode probes. These probes, through hybridization, were immobilized on the reduced graphene oxide and Au nanoparticle (rGO-AuNPs) modified interface and marking the first amplification of the electrical signal. Subsequently, the extended poly T prompted by SIEP bound additional CuNCs through the combination of T-Cu, leading to a second round of signal amplification. The biosensor demonstrated a minimum detection limit of 0.13 fmol/L over a linear response range from 1 fmol/L to 1 nmol/L. It also showcased excellent specificity, repeatability, and stability, making it a promising tool for the sensitive detection of gastric cancer biomarkers.