Cascade-enhanced electrochemical DNA sensing for gastric cancer detection using green-synthesized gold nanoparticles

Gastric cancer remains a major global health burden and still requires sensitive methods for early molecular detection. Herein, we report a cascade-enhanced electrochemical DNA biosensor for the analysis of a p53 mutation sequence associated with gastric cancer. The sensing interface combines Camellia sinensis-mediated gold nanoparticles (AuNPs) with an enzyme-free hybridization chain reaction (HCR) assembled on a screen-printed carbon electrode. UV-Vis spectroscopy, transmission electron microscopy, dynamic light scattering, X-ray diffraction, and Fourier-transform infrared spectroscopy confirmed the formation of stable, predominantly spherical AuNPs with a mean core diameter of 20.4 ± 7.0 nm and a hydrodynamic diameter of about 22 ± 4 nm. Stepwise electrode fabrication was validated by cyclic voltammetry and electrochemical impedance spectroscopy. Under the selected working conditions, the biosensor showed a linear response from 10 fM to 100 pM with a limit of detection of 0.8 fM. The platform also exhibited clear discrimination against a single-base mismatch sequence, acceptable reproducibility (RSD 4.2%), 92% signal retention after 20 days, and satisfactory recovery in spiked serum samples. These data support the feasibility of combining green nanomaterials and enzyme-free nucleic acid amplification for low-level p53 DNA analysis, while further orthogonal validation and clinical testing remain necessary.