The untested empirical medications exacerbated the development of multidrug-resistant Mycobacterium tuberculosis (MDR-TB). Here, we develop a rapid and specific method based on loop-mediated isothermal amplification and duplex-specific nuclease for distinguishing rifampicin-resistant M. tuberculosis. Three probes were designed for the codons 516, 526, and 531 on the RNA polymerase β-subunit (rpoB) gene. These three sites accounted for more than 90% of the total mutations of the ropB gene in the rifampicin-resistant strain. The approach can perform simultaneous and sensitive detection of three mutant sites with the actual detection limit as 10 aM of DNA and 62.5 cfu·mL–1 of bacteria in 67 min under isothermal conditions. Moreover, the positive mode of the approach for MDR-TB can not only deal with the randomness and diversity of mutations but also provide an easier way for medical staff to read the results. Therefore, it is a particularly valuable method to handle major and urgent MDR-TB diagnostics.

The spread of African swine fever virus (ASFV) caused huge economic costs, so early detection is particularly important. Here, we established a fluorescence biosensor based on carbon nanodots (CNDs) and loop-mediated isothermal amplification (LAMP) to ultra-sensitively detect ASFV. LAMP with high efficiency produced a large amount of pyro phosphoric acid and caused pH change in a short time. CNDs with strong light stability had a large fluorescence response at the emission wavelength of 585.5 nm to small pH change by the excitation wavelength of 550 nm. The biosensor realized “turn-off–on” mode for ASFV detection with the detection limit as low as 15.21 copies μL −1 . In addition, the biosensor had high accuracy in the actual sample assay. Therefore, the biosensor achieved rapid, sensitive, low-cost, and simple detection for ASFV. Moreover, the biosensor broadened the detection pathway of LAMP as a tool with great development prospect. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00604-022-05390-7.