Rapid One-Step Detection of Viral Particles Using an Aptamer-Based Thermophoretic Assay

Rapid and sensitive identification of viral pathogens such as SARS-CoV-2 is a critical step to control the pandemic disease. Viral antigen detection can compete with gold-standard PCR-based nucleic acid diagnostics in terms of better reflection of viral infectivity and reduced risk of contamination from enzymatic amplification. Here, we report the development of a one-step thermophoretic assay using an aptamer and polyethylene glycol (PEG) for direct quantitative detection of viral particles. The assay relies on aptamer binding to the spike protein of SARS-CoV-2 and simultaneous accumulation of aptamer-bound viral particles in laser-induced gradients of temperature and PEG concentration. Using a pseudotyped lentivirus model, a limit of detection of similar to 170 particles mu L-1 (26 mu M of the spike protein) is achieved in 15 min without the need of any pretreatment. As a proof of concept, the one-step thermophoretic assay is used to detect synthetic samples by spiking viral particles into oropharyngeal swabs with an accuracy of 100%. The simplicity, speed, and cost-effectiveness of this thermophoretic assay may expand the diagnostic tools for viral pathogens.

Automated summary

The study introduces a one-step thermophoretic assay for rapid and sensitive detection of viral particles, specifically targeting the spike protein of SARS-CoV-2. The assay achieved a low limit of detection in a short time without the need for pretreatment, demonstrating high accuracy when detecting synthetic samples. This thermophoretic assay could potentially enhance diagnostic tools for viral pathogens due to its simplicity, speed, and cost-effectiveness.