Dual-readout autonomous biosensor integrating rolling circle amplification-DNAzyme walker, 3D DNA scaffold, and heterojunction electrode for femtomolar leukemia biomarker detection.

Accurate and early screening of acute myeloid leukemia (AML) is critical for timely intervention and improved patient prognosis. This study presents a self-powered dual-mode biosensing platform for the ultrasensitive detection of AML-associated fusion gene UBA2-WTIP. The platform innovatively integrates a AuNPs/MoS2-graphdiyne (GDY) heterojunction as a high-performance substrate, a structurally stable three-dimensional hexahedral DNA nanopillar as a molecular scaffold, and a cascaded signal amplification strategy driven by target-triggered rolling circle amplification (RCA) and DNAzyme walker-mediated hybridization chain reaction (HCR). The Au/MoS2-GDY heterojunction provides an efficient conductive network that facilitates rapid electron transfer, significantly enhancing the output signal. The engineered hexahedral DNA nanostructure offers abundant binding sites and superior stability for subsequent nucleic acid assembly. Upon target recognition, protect DNA is displaced, activating RCA process to generates long DNA strands containing numerous DNAzyme units. These DNAzymes, in the presence of Mg2+, cleave substrates to release initiator strands, which in turn trigger an autonomous HCR on the electrode. This cascade results in the in situ formation of extended dsDNA polymers, which entrap the electrochromic molecule methylene blue, producing easily measurable electrochemical response and distinct color change. The proposed biosensor demonstrates a wide linear range from 0.1 fM to 10 nM for UBA2-WTIP, with low detection limits of 27.7 aM (electrochemical) and 49.4 aM (colorimetric) (S/N = 3), alongside built-in self-verification and correction for enhanced reliability. This work establishes a powerful and reliable sensing strategy, highlighting the great potential of integrated DNA nanotechnology and bioenzyme-based biofuel cells for the early diagnosis of hematological malignancies.