A facile visualized solid-phase detection of virus-specific nucleic acid sequences through an upconversion activated linear luminescence recovery process.

The development of portable solid-phase biosensors is of great significance for point-of-care testing (POCT). In this work, we constructed a simple visualized solid-phase biosensor based on luminescence resonance energy transfer (LRET) from upconversion nanoparticles (UCNPs) to gold nanoparticles (AuNPs) for quantitative detection of virus-specific nucleic acid sequences. The detection data showed that there was a linear relationship between the luminescence recovery of UCNPs and the concentrations of the target within the range of 5-100 nM, and the limit of detection (LOD) was 0.326 nM. Additionally, the luminescence recovery of UCNPs was visualized and quantitatively analyzed using a home-built luminescence image capture device and an open-source ImageJ software that can analyze and process images. Compared with conventional liquid-phase biosensors, the solid-phase analysis method we constructed not only has advantages in cost, portability and stability, but also is more conducive to the rapid acquisition and storage of the detected sample, which is expected to become a fast, efficient and reliable detection platform for POCT.