Electrochemical aptamer-based biosensors for biomarker detection assisted by tetrahedral DNA nanostructures

Continuous detection of proteins is crucial for health management and biomedical research. Electrochemical aptamer-based (E-AB) sensors that rely on binding affinity between a recognition oligonucleotide and its specific target provide a versatile platform to fulfill this purpose. Yet, most E-AB sensors are characterized by voltammetric methods, which suffer from signal drifts and low-frequency data acquisition during continuous operations. To overcome these limitations, we developed two novel E-AB sensors empowered by 1) gold nanoparticle-DNA pendulum (GDP), and 2) tetrahedral DNA nanostructure (TDN) pendulum. By integrating with chronoamperometric technic, the developed sensors enabled drift-resistant, high-frequency, and real-time monitoring of two important protein biomarkers, vascular endothelial growth factor (VEGF) and thrombin. In the presence of target molecules, longer and concentration-dependent time decay was observed, because of the reduced motion of the probes in their bound states. After optimizing several decisive parameters, such as probe density and incubation time, the developed E-AB sensors achieve continuous, selective, and reversible monitoring of targets in both phosphates buffered saline (PBS) solutions and artificial urine. Moreover, the developed sensors acquire signals on a millisecond timescale and remain resistant to signal degradation during long-term operation. This study offers a new approach to designing E-AB architectures for continuous biomolecular monitoring.