Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing Rhodamine 6G luminescent molecules

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Luminescent silicon dioxide nanoparticles (R–SiO 2) with size of 50 nm containing Rhodamine 6G (R) were synthesized by sol–gel method. In the presence of Pb(Ac) 2 as a heavy atom perturber, the particle can emit intense and stable room temperature phosphorescence signal of R, respectively, on polyamide membrane, with the λ ex max / λ em max = 470 / 635 nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R–SiO 2 and human IgG can be carried on polyamide membrane quantitatively, and the phosphorescence intensity 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 nanoparticles containing binary luminescent molecules. The linear range of this method is 0.0624–20.0 pg spot −1 of human IgG (corresponding concentration, 0.156–50.0 ng mL −1; sample volume, 0.40 μL spot −1). The regression equations of working curves are Δ I p = 88.16. + 16.79m IgG (pg spot −1) (485/646 nm, r = 0.9997). Detection limits calculated by 3Sb/k are 0.017 pg spot −1. For samples containing 0.156 and 50.0 ng mL −1 of IgG, we measured repeatedly for 11 times, RSDs are 3.9 and 2.8%, respectively. This method is sensitive, accurate and of high precision.