Construction of broom-like Ag@N,O-C sensing interface for electrochemical detection of circulating tumor DNA using entropy-driven DNA walker

In human peripheral blood, circulating tumor DNA (ctDNA) is an excellent tumor biomarker for noninvasive diagnosis, therapy and prognosis of cancer. Herein, an innovative enzyme-free electrochemical sensor sensitized with broom-like Ag@N,O-C hierarchical nanomaterials and entropy-driven DNA walker was designed for PIK3CA E545K ctDNA assay. In this work, N, O-doped carbon layers were used to completely coat Ag nanoparticles, and then were assembled into three-dimensional broom-like nanomaterials with hierarchical structure. The application of Ag@N,O-C broom-like hierarchical nanomaterials (Ag@N,O-C BLHS) as electrode material not only facilitated electron transfer, but also increased functional active sites for a high-density assembly of DNA walking substrates. Via the entropy-driven catalytic reaction of DNA walker, one target ctDNA initiated the dissociation of abundant electroactive tags from the electrode surface, achieving a one-to-multiple amplification effect. By measuring electrochemical responses, PIK3CA E545K ctDNA was quantified with 10 aM detection limit. Additionally, the enzyme-free amplified sensing interface achieved the direct detection of ctDNA in plasma samples from breast cancer patients and healthy human. Overall, the good selectivity, reproducibility and practical application ability confirmed a promising potential of the sensor for disease diagnosis.

Automated summary

An innovative enzyme-free electrochemical sensor was designed using broom-like Ag@N,O-C hierarchical nanomaterials and entropy-driven DNA walker to analyze PIK3CA E545K ctDNA. The sensor demonstrated good selectivity, reproducibility, and practical application ability, making it a promising tool for disease diagnosis.