Demonstration and structural basis of a therapeutic DNA aptamer for SARS-CoV-2 spike protein detection.

Publication date: Nov 01, 2025

At the onset of the COVID-19 pandemic, the absence of rapid and precise diagnostic tools hindered early detection and response. To address this challenge, we developed a renewable electrochemical impedance biosensor (aptasensor) using a therapeutic DNA aptamer immobilized on a nanostructured gold nanoparticle/carbon nanotube (AuNP/CNT) electrode to detect the SARS-CoV-2 spike (S) protein receptor-binding domain (RBD). The aptasensor achieved a limit of detection of 0. 19 pg mL and a dynamic range from 1 to 10 pg mL. Following regeneration with a 60-s pH 2. 0 rinse, the sensor retained over 90% of its original signal across five cycles and remained stable after two weeks of ambient storage. Dual-mode readouts, utilizing impedance spectroscopy and surface plasmon resonance (SPR), confirmed binding specificity and reproducibility. Cryogenic electron microscopy (cryoEM) resolved the aptamer-S protein complex in the open conformation, revealing a bridge-like interaction with conserved residues Y489, N487, F486, and S477. These contacts remained functional despite Omicron BA. 2 mutations (S477N, N501Y) and aligned with previously reported mutational data. Specificity was further supported by negative controls and structural consistency with known hACE2 binding footprints. These results establish a robust, low-cost biosensor platform combining reuse, structural insight, and variant tolerance. The aptasensor’s scalability and adaptability make it a strong candidate for future diagnostic applications targeting evolving viral threats.

Semantics

Original Article