A novel chemiluminescence signal amplification strategy based on a capillary electrophoresis platform for highly sensitive competitive immunoassay of biomolecules

Abstract

Capillary electrophoresis (CE) is currently one of the most important separation and analysis techniques for application in biology and medicine. However, an extremely small sample size poses a challenge for achieving high detection sensitivity in CE. In this work, we developed a novel chemiluminescence (CL) signal amplification strategy based on luminophore and antigen co-loaded gold nanoparticles (AuNPs) to improve the sensitivity of CE-CL assay. AuNPs have a large surface area, which can increase the loading quantity of the luminophore and the antigen (Ag). Based on competitive immunoreactions on the AuNP surface and CE separation, the detection of the target was transformed for the detection of AuNPs loaded with the luminophore and the Ag. Thus, AuNPs were used as carriers of the luminophore to achieve amplification of the CL signal by increasing the loading. Testosterone (Te) was used as a model analyte in the current proof-of-concept experiments, and the peak height (CL intensity) of AuNPs loaded with the luminophore and the Ag showed a good linearity with the concentrations of Te ranging from 0.20 pg mL⁻¹ to 10 pg mL⁻¹. The limit of detection (S/N = 3) was estimated to be 0.11 pg mL⁻¹ (3.8 × 10⁻¹³ M). The present method has been applied for the detection of trace Te in female serum samples. Moreover, the proposed strategy for enhancing the sensitivity of CE-CL-IA appears to be a universal approach for the detection of various trace biomolecules by simply changing the target Ag and antibody (Ab).