DNA Tetrahedron-Mediated Sensing Platform on a Single Gold Nanowire: Special Signal Amplification, Self-Referencing...

Exosomes have emerged as promising biomarkers for noninvasive cancer diagnosis, while highly sensitive, reliable, and convenient assays remain challenging, particularly with conventional single-signal approaches. Herein, we report an exosome-tailored dual-mode self-referencing biosensing platform on a single gold nanowire (AuNW) substrate for the accurate and sensitive quantification of HepG2-derived exosomes, integrating surface-enhanced Raman scattering (SERS) and electrochemical readouts on a AuNW substrate with dual-functional Au nanotag amplification. The platform features three exosome-specific design strategies: CD63 aptamer-functionalized DNA tetrahedrons (AD-NTH) with well-controlled probe orientation, spacing, and accessibility to enhance exosome capture efficiency and mitigate interfacial steric hindrance; dual recognition via CD63-mediated capture and AFP-mediated signal tagging for improved specificity toward HepG2-derived exosomes; and a ratiometric SERS/electrochemical dual-mode readout on a unified substrate to enhance signal reliability. This self-referencing mechanism effectively suppresses nonspecific interference and signal fluctuation, while the dual-functional Au nanotags provide amplified signal outputs. The platform achieves detection limits of 8.41 × 10² particles mL^-1 (SERS) and 1.07 × 10³ particles mL^-1 (electrochemical). Clinical evaluation using serum samples from 10 liver cancer patients and 10 healthy volunteers shows statistically significant differentiation (P < 0.0001), supporting its promising application in noninvasive early screening and diagnosis of liver cancer.