Abstract:In this work,a sensitive fluorescent bioassay was developed for the detection of gramnegative bacterium Salmonella specific target DNA sequences. The NaYF4 :Yb3 +Er3 +upconversion nanoparticles(UCNPs) was prepared with high green upconversion fluorescent intensity. The biotinylated Salmonella target DNA complementary sequence 2 was attached to the avidin-conjugated UCNPs and served as the fluorescent signal probe. Then,the as-prepared Fe3 O4 magnetic nanoparticles(MNPs) was first surface modified with avidin molecule,and then combined with the biotinylated Salmonella target DNA complementary sequence 1 which served as the magnetic capture probe. The target DNA could be detected based on the DNA hybridization reaction. The fluorescent intensity was proportional to the concentration of target DNA in the range of 0.01 pmol/L to 10 pmol/L with detection limit as low as 3 fmol/L. The presented upconversion fluorescent method is simple,fast,sensitive,specific,and furthermore,it offers another great promise for the application of nanomaterials in biosensor design.
