Electrochemical Immunoassay for Cytomegalovirus Antigen Detection with Multiple Signal Amplification Using HRP and Pt-Pd Nanoparticles Functionalized Single-walled Carbon Nanohorns

Cytomegalovirus is typically associated with immunocompromised hosts, pregnant women and transplant patients, who require a timely diagnosis. In this work, a sensitive and highly specific electrochemical amplification immunosensor was established for detecting Cytomegalovirus pp65 antigen based on Pt-PdNPs@SWCNHs with horseradish peroxidase (HRP) as a signal enhancer and thionine as a signal probe. First, Pt nanoparticle (PtNP) and Pd nanoparticle (PdNP) functionalized single-walled carbon nanohorn (SWCNH) nanocomposites, i.e. Pt-PdNPs@SWCNHs, was used as a carrier for immobilization of antibody through the Pt-N bond and the Pd-N bond. Next, HRP was used to block the rest of the binding-sites. Signal amplification was obtained by the cooperative catalytic activities of Pt-PdNPs and HRP to H2O2. SWCNHs loaded with a large amount of Pt-PdNPs further amplified the signal due to the excellent surface area. The fabricated immunosensor was used to detect different concentrations of Cytomegalovirus pp65 antigen under optimized conditions. The tests showed a linear range from 0.1 to 80 ng mL(-1) with a low detection limit of 30 pg mL(-1), and exhibited excellent selectivity, stability and reproducibility. Therefore, this project presented a potential approach for the early diagnosis of Cytomegalovirus infection in clinical trials.