title: A Novel Europium Chelate Coated Nanosphere for Time-Resolved Fluorescence Immunoassay.
abstract: A novel europium ligand 2,2',2'',2'''-(4,7-diphenyl-1,10-phenanthroline-2,9-diyl) bis (methylene) bis (azanetriyl) tetra acetic acid (BC-EDTA) was synthesized and characterized. It shows an emission spectrum peak at 610 nm when it is excited at 360 nm, with a large Stock shift (250 nm). It is covalently coated on the surface of a bare silica nanosphere containi free amino groups, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-Hydroxysuccinimide. We also observed an interesting phenomenon that when BC-EDTA is labeled with a silica nanosphere, the chelate shows different excitation spectrum peaks of about 295 nm. We speculate that the carboxyl has a significant influence on its excitation spectrum. The BC-EDTA/Eu3+coated nanosphere could be used as a fluorescent probe for time-resolved fluorescence immunoassay. We labeled the antibody with the fluorescent nanosphere to develop a nanosphere based hepatitis B surface antigen as a time-resolved fluorescence immunoassay reagent, which is very easy to operate and eliminates potential contamination of Eu3+ contained in the environment. The analytical and functional sensitivities are 0.0037 μg/L and 0.08 μg/L (S/N≥2.0) respectively. The detection range is 0.08-166.67 μg/L, which is much wider than that of ELISA (0.2-5 μg/L). It is comparable to the commercial dissociation-enhanced lanthanide fluoro-immunoassay system (DELFIA) reagents (0.2-145 μg/L). We propose that it can fulfill clinical applications.
authors.affiliation: Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China; Triplex International Bioscience (China) CO., Ltd., Xiamen, Fujian, China.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Shen
authors.affiliation: The First Affiliate Hospital of Fujian Medical University, Fuzhou, Fujian, China.
authors.forename: Shaohan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Triplex International Bioscience (China) CO., Ltd., Xiamen, Fujian, China.
authors.forename: Donghua
authors.initials: D
authors.lastname: He
mesh_terms: D000906:Antibodies / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000138:chemical synthesis / Q000737:chemistry; D005063:Europium / Q000737:chemistry*; D015200:Fluoroimmunoassay / Q000379:methods*; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D054118:Nanospheres / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013194:Staining and Labeling; D013997:Time Factors
chemical_list: D000906:Antibodies; D002614:Chelating Agents; D006514:Hepatitis B Surface Antigens; D005063:Europium; D012822:Silicon Dioxide; D004492:Edetic Acid