Nano‐Mechanical DNA Devices Coupled With CRISPR‐Cas12a for CA15‐3 Detection

ABSTRACT Accurate monitoring of cancer markers is crucial for clinical treatment and prognosis. CA15‐3 activity levels are strongly associated with clinical progression of breast cancer, but their monitoring often relies on large instruments and professionals, and the process is time‐consuming and costly. To address these concerns, we proposed an electrochemical biosensing strategy that integrated nano‐mechanical DNA devices coupled with the CRISPR‐Cas12a to drive molecularly gated functionalized substrates for the ultrasensitive detection of CA15‐3. Specifically, Triple helical molecular switch (THMS) as a signal input switch to ensure target recognition specificity and the diffusion‐limited 3D DNA walking machine coupled with CRISPR‐Cas12a technology as signal amplification means. Based on the bimolecular dynamics model, the rate constants k ₁ (1.40 × 10 ⁵ M ⁻¹ sec ⁻¹ ) and k ₂ (2.5 × 10 ⁴ M ⁻¹ sec ⁻¹ ) of the GNP‐PEG(+)/T 3D orbitals modified with positively charged SH‐PEG‐NH ₂ are larger than those of unmodified orbitals, proving that nanointerface diffusion restriction effect can accelerate the toehold‐mediated chain displacement reaction (TMDR). With the assistance of Co‐N/C modified screen‐printed electrode (SPE‐Co‐N/C) sensing interface, the calculated detection limit of CA15‐3 is as low as 7.14 × 10 ⁻⁶ U mL ⁻¹ . The proposed assay, which demonstrated satisfactory selectivity and reproducibility, and correlated highly with ELISA kit results, offered a promising tool for breast cancer early detection and therapeutic monitoring.