Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing dibromofluorescein luminescent molecules Original Research Article

Luminescent silicon dioxide nano-particles with size of 20 nm, which containing dibromofluorescein (D) were synthesized by sol–gel method (symbolized by D–SiO2).The particles can emit intense and stable room temperature phosphorescence signal on polyamide membrane when Pb(Ac)2 was used as a heavy atom perturber. The λexmax/λemmax was 457/622 nm. Our research indicated that the specific immune reaction between goat-anti-human IgG antibody labeled with D–SiO2 and human IgG could be carried out on polyamide membrane quantitatively, and the phosphorescence intensity of the particle was enhanced after the immunoreactions. Thus a new method of solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human IgG was established basing on antibody labeled with the D–SiO2 nanoparticles. The linear range of this method was 0.0624–20.0 pg human IgG spot−1 (corresponding concentration: 0.156–50.0 ng ml−1, the sample volume: 0.40 μl spot−1) with a limit of detection (LD) as 0.018 pg spot−1, and the regression equation of working curve was ΔIp = 7.201 mIgG (pg spot−1) + 82.57. Samples containing 0.156 and 50.0 ng ml−1 of IgG were measured repeatedly for 11 times and R.S.D.s were 4.1 and 3.4%, respectively. Results showed that this method had the merits as sensitive, accurate and precise.