Voltammetric aptasensor combined with magnetic beads assay developed for detection of human activated protein C

A sensitive and selective label free voltammetric aptasensor based on magnetic beads assay was performed for the first time in our study for monitoring of human activated protein C (APC), which is a serine protease (i.e., key enzyme of the protein C pathway). An amino modified DNA aptamer (DNA APT) was covalently immobilized onto the surface of carboxylated magnetic beads (MBs), and then, the specific interaction between DNA APT and its cognate protein, APC, was performed at the surface of MBs. Similarly a biotinylated DNA APT was immobilized onto the surface of streptavidin coated MBs. Before and after interaction process, the oxidation signal of guanine was measured at disposable pencil graphite electrode (PGE) surface in combination with differential pulse voltammetry (DPV) technique and accordingly, the decrease at the guanine signal was evaluated. The biomolecular recognition of APC was successfully achieved with a low detection limit found as 2.35 µg mL−1 by using MB-COOH based assay. Moreover, the selectivity of this aptasensor assay was tested in the presence of numerous proteins and other biomolecules: protein C (PC), thrombin (THR), bovine serum albumin (BSA), factor Va (FVa) and chromogenic substrate (KS).