Use of DNA nanosensors based on upconverting nanoparticles for detection of Nosema bombycis by fluorescence resonance energy transfer

In this study, NaYF4:20%Yb, 2%Er upconverting nanoparticles (UCNPs) were synthesized by solvothermal method and characterized by transmission electron microscopy and upconversion fluorescence spectrometry. The results showed that the UCNP particles present good dispersion and uniform spherical shape with a size of 29 similar to 42 nm. Hydroxyl UCNPs were converted to hydrophilic carboxylic acid-functionalized ones by ligand exchange, and the streptavidin was attached on the surface of carboxylic acid-functionalized UCNPs via amide bond. The DNA nanosensors based on UCNPs with DNA probes have been successfully developed. Only the genomic DNA of Nosema bombycis can be specifically detected by the DNA nanosensors when the DNA of Bombyx mori and its pathogens was used as target DNA. When the DNA nanosensors were used to detect the DNA of N. bombycis, a broad emission peak signal appeared at 580 nm. There is linear relationship between the signal intensity and DNA concentration of N. bombycis, I-580/I-5(45) (R-2 = 0.820) and I-545/I-6(54) (R-2 = 0.901). The detectable minimum concentration of genomic DNA of N. bombycis was 100 ng/mu L while the tested concentrations of N. bombycis genomic DNA were 3000 ng/mu L, 1500 ng/mu L, 1000 ng/mu L, 500 ng/mu L, 250 ng/mu L, and 100 ng/mu L, respectively. The whole detection process for target DNA takes less than 60 min.