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

Luminescent silicon dioxide nanoparticles (R-SiO2) 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 λexmax/λemmax=470/635nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R-SiO2 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 ΔIp = 88.16. + 16.79mIgG (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.