Aptamer-functionalized nanopipettes: a promising approach for viral fragment detection via ion current rectification†

In this report, ion current rectification, an electrochemical phenomenon observed in asymmetric nanopipettes, is used for the label-free detection of SARS-CoV-2 viral fragments in nasopharyngeal samples. Quartz nanopipettes are functionalized with aptamers targeting the spike protein S1 domain, wherein changes to the surface charge magnitude, distribution, and ion transport behavior modulate the current–voltage response upon binding. The aptamer-modified nanopipette provides a selective and sensitive method for detecting SARS-CoV-2, with a limit of detection in the laboratory of 0.05 pg mL⁻¹. The effectiveness of this low-cost platform was demonstrated by sensing SARS-CoV-2 in nasopharyngeal samples, successfully discriminating between positive and negative cases with minimal template preparation, highlighting the platform's potential as a versatile sensing strategy for infectious disease detection in clinical diagnosis.