Fig. 3: Validating the advantages of the Self-confined Tetrahedral DNA Circuit (SCTD) regarding signal amplification, enhanced mechanical stability, antifouling capability, and long-term stability.

a Schematic illustration of the sensing mechanism with and without SCTD. b PAGE analysis showing the self-assembly of TDNA and various combinations of TDNA sequences. lane 1: marker (20–500 bp), lane 2: P1, lane 3: P2, lane 4: P3, lane 5: P4, lane 6: P1 + P2, lane 7: P1 + P2 + P3, lane 8: P1 + P2 + P3 + P4. This experiment was repeated three times independently with similar results. Fluorescent (c) and electrochemical (d) characterization of the feasibility of the biosensing strategy. e Calibration curve for the detection of IL-6 in the absence and presence of an amplification circuit (n = 5 independent experiments). Data are presented as mean ± SD. f–i Comparison of mechanical stability between ssDNA- and TDNA-based biosensing electrodes: schematic illustrations of structural deformation (f, h) and corresponding electrochemical signal variations (g, i) during 1000 bending cycles. Radius of bending curvature, 3 cm. j The schematic diagram illustrating the antifouling performance of TDNA against BSA. CLSM images (k) and corresponding fluorescence intensity (l) of different electrodes fouled in BSA-FITC for 3 h (n = 3 independent experiments). The experiment was independently repeated three times with similar results. Data are presented as mean ± SD. Scale bar, 500 μm. m Comparison of the BSA adhesion ratios by different electrodes measured by BCA assay (n = 3 independent experiments). Data are presented as mean ± SD. n Comparison of the water contact angles between different electrodes (n = 4 independent experiments). Data are presented as mean ± SD. o Radar plot demonstrating the superior performance of TDNA-based biosensors over ssDNA-based biosensors in LOD, antifouling, anti-bending, and antidegradation capabilities. Source data from (b–e, g, i, l–o) are provided as a Source Data file.