Screening for cystic fibrosis via a magnetic and microfluidic immunoassay format with electrochemical detection using a copper nanoparticle-modified gold electrode

This article describes a microfluidic electrochemical immunoassay that features two strategies, viz. (a), the incorporation of magnetic nanoparticles (MNPs) into the central microfluidic channel and acting as a bioaffinity support for the immobilization of the antibody against the immunoreactive trypsin (anti-IRT), and (b), the electrodeposition of copper nanoparticles (CuNPs) on a gold electrode. IRT, a marker for cystic fibrosis, is extracted from blood samples onto a disk using ultrasonication, eluted, and then injected into the detection system where it is captured by anti-IRT-loaded nanoparticles (anti-IRT-Ab-MNPs). Bound IRT is electrochemically quantified after addition of HRP-labeled anti-IRT-Ab which, in the presence of H2O2, catalyzes the oxidation of catechol to form o-benzoquinone which is detected at a working potential of -150 mV (vs. Ag/AgCl). The electrochemical response to benzoquinone is proportional to the concentration of IRT in the range from 0 to 580 nga <...mL(-1). The coefficients of variation are < 5 % for within-day assays, and < 6.4 % for between-day assays. The method was compared to a commercial ELISA for IRT where is showed a correlation coefficient of close to 1. In our perception, this approach represents an attractive alternative to existing methods for screening newborns for cystic fibrosis.