An electrochemical dual-aptamer biosensor based on metal-organic frameworks MIL-53 decorated with Au@Pt nanoparticles and enzymes for detection of COVID-19 nucleocapsid protein

The development of COVID-19 detection strategies with high sensitivity and selectivity are urgent for early diagnosis. Herein, we constructed an electrochemical dual-aptamer biosensor based on the metal-organic frameworks MIL-53(Al) decorated with Au@Pt nanoparticles and enzymes to determine SARS-CoV-2 nucleocapsid protein (2019-nCoV-NP) via co-catalysis of the nanomaterials, horseradish peroxidase (HRP) and G-quadruplex DNAzyme. First, the two thiol-modified aptamers (N48 and N61), as recognition elements, were immobilized on the surface of gold electrode (GE) to capture the biomarker 2019-nCoV-NP. Then, the nanomaterial composites Au@Pt/MIL-53 (Al) were decorated by HRP and hemin/G-quadruplex DNAzyme as signal nanoprobe. The designed nanoprobe was applied to amplifying the aptasensor signal via co-catalyzing the oxidation of hydroquinone in the presence of hydrogen peroxide. Finally, the aptamer-protein-nanoprobe sandwich electrochemical detection system was fabricated on the GE surface. The results demonstrated that this aptasensor had a wide linear range from 0.025 to 50 ng mL−1 and the detection limit was 8.33 pg mL−1 for 2019-nCoV-NP. This aptasensor has great potential in the early diagnosis of COVID-19 with high sensitivity, selectivity and reliability.