Amperometric magnetoimmunoassay for the determination of lipoprotein(a)

AbstractA highly sensitive amperometric magnetoimmunoassay for rapid determination of lipoprotein(a) (Lp(a)), an important predictor of cardiovascular disease risk, in human serum, is described. It uses a sandwich configuration involving selective capture antibody [antiLp(a)] and biotinylated detector antibody [biotin-antiLp(a)], and a streptavidin-HRP conjugate on carboxy-modified magnetic beads (HOOC-MBs). The resulting MBs bearing the sandwiched immunoconjugates were captured by a magnet placed under the working electrode surface of a disposable screen-printed carbon electrode and the extent of the affinity reaction was monitored amperometrically at −0.20 V (vs a silver pseudo-reference electrode) in the presence of hydroquinone as an electron transfer mediator and upon addition of H2O2 as the enzyme substrate. The method exhibited a wide linear response range (from 0.01 to 0.5 μg mL−1), a detection limit of 4 ng mL−1, and an excellent selectivity over other serum components. The utility of the immunoassay was demonstrated by analyzing a reference serum containing a certified quantity of Lp(a). The performance of this magnetoimmunoassay compares favorably to that of an integrated amperometric immunoassay described earlier. Graphical AbstractThe article describes the first disposable and highly sensitive amperometric magnetoimmunoassay for lipoprotein(a), an important predictor of cardiovascular disease risk, in human serum. It is  based on a sandwich configuration involving selective capture antibody and biotinylated secondary antibody, and a streptavidin-HRP conjugate on magnetic beads.