DNA tweezer-assembled, regenerated nanosensor for one-step and sustainable detection of viral RNA and Hg2+

Abstract

Transcription-polymerase chain reaction (RT-qPCR) is the golden standard to detect viral RNA. However, it suffers from several inherent defects such as high false-negative rates, time-consuming and expensive. To exploit better analytical methods for future global pandemics, it is vital to develop rapid, sustainable, and environmentally-friendly sensing methods. Here, a one-step, regenerated nanosensor assembled by DNA tweezers is developed for rapid and sustainable detection of viral RNA. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA is selected as model analyte. The DNA tweezer is designed with a central strand and two arm strands containing overhangs complementary to SARS-CoV-2 RNA. The SARS-CoV-2 RNA hybridizes with the two arm overhangs and strains the DNA tweezer to closed conformation, resulting in the close proximity of the donor and acceptor fluorophores. With the addition of an anti-strand complementary to the SARS-CoV-2 RNA, the closed DNA tweezer is relaxed to open conformation through a strand displacement process, leading to the separation of the dual fluorophores. Thus, the DNA tweezer is revived for fresh SARS-CoV-2 RNA. The proposed nanosensor can be regenerated for three cycles with the same performance. Moreover, the viral RNA can be detected within 30 min with a detection limit of 0.04 nM. By altering the sequences of the DNA tweezer, rapid, sensitive, and sustainable detection of Hg2+ is achieved. The proposed nanosensor provides a novel approach for rapid, flexible, and sustainable detection of viral RNA and Hg2+, exhibiting great potential for routine preliminary coronavirus disease tests, epidemic control, and environmental monitoring.