Highly sensitive capillary electrophoretic immunoassay of rheumatoid factor in human serum with gold nanoparticles enhanced chemiluminescence detection

Abstract

A new CE-based immunoassay method for the determination of rheumatoid factor was developed using chemiluminescent reaction of luminol and hydrogen peroxide catalyzed by gold nanoparticles (AuNPs). In this method, AuNPs were synthesized and conjugated with anti-RF (antibody, Ab) to form tagged Ab (AuNPs-Ab, Ab*), which subsequently linked to limited amount of RF (antigen, Ag) to produce Ab*-Ag complex by a noncompetitive immunoreaction. AuNPs were used to label antibody and amplify chemiluminescent signal. Under the optimized conditions, the mixture of free Ab* and Ab*-Ag complex was well separated and detected. This method yields a wide linear range of 0.01-20 μg/mL with a correlation coefficient of 0.997, and the detection limit of RF reaches 5.95 ng/mL (ca. 6.0 pmol/L, S/N = 3). The proposed method was successfully applied for the quantification of RF in human sera from patients with rheumatoid arthritis. This highly sensitive and selective method could be developed into a promising and useful technique for biological molecules determination in clinical analysis.