Functionalized bismuth quantum dots induced fluorescence resonance energy transfer with target-driven loop-mediated isothermal amplification for visual African swine fever detection

Sensitive, simple and visual detection methods have become the focus of research because they can realize realtime detection without rely on the various detection instruments, so it is of great significance to apply them to the detection of African swine fever virus (ASFV). In this work, functionalized bismuth quantum dots (Bi QDs) were prepared by hydrothermal method and used in loop-mediated isothermal amplification (LAMP) reaction to replace the fluorescent dyes. Due to the overlap of the spectra of Bi QDs and titanium carbide (Ti3C2) nanosheet, the fluorescence resonance energy transfer (FRET) phenomenon could occurred between the Bi QDs and Ti3C2 nanosheet, and Ti3C2 nanosheets were used as energy acceptor and Bi QDs were used as fluorescence donors, which resulted in the quench of Bi QDs fluorescence signal. When the target ASFV was present, the LAMP reaction was activated due to the specific binding between the primer and the target result the separation of the Bi QDs from the surface of the Ti3C2 nanosheets, which leading to fluorescence recovery. Thus a target-driven fluorescence recovery sensing system for ASFV detection was developed. The detection results of the sensing system showed that the visual blue fluorescence recovered gradually in the range of 5.0 x 10-12-1.0 x 10-6 g/L with the detection limit of 1.5 x 10-12 g/L (2.4 copies/mu L) and satisfactory detection results were obtained in the infected ASFV samples. The proposed fluorescent visual sensing detection strategy opens up a new way for sensitive, simple and visual nucleic acid detection.