Abstract: Europium nanoparticles were prepared using tannic acid as the reductive agent in sodium dodecylbenzene sulfonate solution searching for a novel fluorimetric method of proteins determination. Nanoeuropium OMP conjugates were synthesized by the method of lipoic acid modification on the nanoparticles surface. The fluorescence changes, mechanisms of europium nanoparticles and the conjugates of europium nanoparticles with OMP were analyzed by fluorophotometer. The relationship between fluorescence changes and the concentration of OMP was also studied. The fluorescence intensity of nanoeuropium OMP conjugates was significantly increased compared with that of europium nanoparticles，which was linearly proportional to the concentration of OMP in the range of 0.020～8.0mg/L, and the detection limit was 0.012mg/L under optimum conditions. The relative standard deviation (n=11) was 2.4% for 5.0mg/L OMP. The effect of an olfactory marker protein on the fluorescence enhancement of europium nanoparticles can be attributed to the result of the energy transfer of OMP among molecules. This method can be used to determine the concentration of OMP.

Key words: fluorescence , olfactory marker protein, lipoic acid, sodium dodecylbenzene sulfonate, europium nanoparticles