Label-free detection of C-reactive protein using a carbon nanofiber based biosensor

We report the sensitive detection of C-reactive protein (CRP), a biomarker for cardiac disease, using a carbon nanofiber based biosensor platform. Vertically aligned carbon nanofibers were grown using plasma enhanced chemical vapor deposition to fabricate nanoelectrode arrays in a 3×3 configuration. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the CRP detection. The CV responses show a 25% reduction in redox current upon the immobilization of anti-CRP on the electrode where as a 30% increase in charge transfer resistance is seen from EIS. Further reduction in redox current and increase in charge transfer resistance result from binding of CRP on anti-CRP immobilized surface, proportional to the concentration of the CRP target. The detection limit of the sensor is found to be ~90 pM or ~11 ng/ml, which is in the clinically relevant range. Control tests using non-specific myoglobin antigen confirmed the specificity of the present approach.