Label-free and direct detection of C-reactive protein using reduced graphene oxide-nanoparticle hybrid impedimetric sensor

For label-free and direct detection of C-reactive protein (CRP), an impedimetric sensor based on an indium tin oxide (ITO) electrode array functionalized with reduced graphene oxide-nanoparticle (rGO-NP) hybrid was fabricated and evaluated. Analytical measurements were performed to examine the properties of rGO-NP-modified ITO microelectrodes and to determine the influence upon sensory performance of using nanostructures modified for antibody immobilization and for recognition of CRP binding events. Impedimetric measurements in the presence of the redox couple [Fe(CN)₆]^3-/4- showed significant changes in charge transfer resistance upon binding of CRP. The impedance measurements were highly target specific, linear with logarithmic CRP concentrations in PBS and human serum across a 1ngmL^-1 and 1000ngmL^-1 range and associated with a detection limits of 0.06 and 0.08ngmL^-1 respectively.