CE immunoassay with enhanced chemiluminescence detection of erythropoietin using silica dioxide nanoparticles as...

The measurement of serum erythropoietin (EPO) is important for the detection of recombinant human EPO misuse in sports. In this paper, we have developed a sensitive and rapid CE immunoassay with enhanced chemiluminescence detection of EPO, in which silica dioxide nanoparticles (SiO2 NPs) were used as the pseudostationary phase to improve the separation efficiency of analytes. By adopting SiO2 NPs in the CE immunoassay, the separation can be successfully performed in neutral running buffer solution. However, running buffer of extreme pH was still necessary for the conventional CZE mode. Neutral phosphate buffer (pH 7.4) containing SiO2 NPs and poly(ethylene oxide) (PEO) was chosen as running buffer. The influences of SiO2 NPs, PEO and buffer concentration on the separation efficiency and EPO detection were investigated. EPO-horse radish peroxidase (HRP) and immunocomplex were baseline separated in a 10 mM phosphate buffer (pH 7.4) consisting of 0.08% PEO and 0.08% SiO2 NPs. The linear range for EPO was 1.8-158.0 ng/mL and the detection limit was 0.9 ng/mL. The assay was successfully applied for the quantification of EPO in human sera and the results correlated well with those obtained using chemiluminescence immunoassay kits, thus demonstrating that the present method was a potential powerful tool for EPO misuse detection and clinical diagnosis.