Label-free detection of cardiac biomarker using aptamer based capacitive biosensor

Official URL: http://dx.doi.org/10.1016/j.proeng.2010.09.236

An aptamer based capacitive label-free biosensor was developed for the detection of a cardiac biomarker (C-reactive protein, CRP), based on charge distribution under the applied frequency by Non-Faradaic Impedance Spectroscopy. This capacitive biosensor is based on reagentless processing and developed using gold-interdigitated (GID) capacitor arrays functionalized with synthetic RNA-aptamers. The change in relative capacitance occurred by formation of RNA-CRP complex on GID-capacitors against the applied AC electrical frequency (50–350 MHz) was measured. The binding affinity (Kd) of the RNA-aptamer with CRP was determined and the results showed that at frequencies of 208 and 306 MHz the strong binding occurred with View the MathML source and View the MathML source, respectively. The dynamic range for CRP was determined to be within 100–500 pg/ml. Our results demonstrate the sensitive detection of RNA-protein complex on GID-capacitors under the applied electric field, which can be extended to other disease protein biomarkers for the development of electrical biosensors.