Objective
We concentrated in an immunosensor for C-reactive protein (CRP). CRP is one of the acute phase proteins that increase during systemic inflammation. It’s been suggested that testing CRP levels in the blood may be a new way to assess cardiovascular disease risk. Elevated CRP level is related to increased risk for heart attack, restenosis of coronary arteries after angioplasty, stroke, and peripheral vascular disease (PVD) .
This work describes the development of an electrochemical immunosensor based on a gold electrode coated with carbon nanotubes (CNT) and Anti-CRP IgG for detection of CRP. Schematic illustration of the sensor is shown in Figure 1. The Anti-CRP IgG were covalently bonded (via polyethyleneimine and glutaraldehyde) to the electrodes surfaces. The electrode was immersed first in a human serum enriched in CRP and afterwards in a buffer containing secondary anti-CRP IgG coupled to a horseradish-peroxidase (HRP) marker. The enzymatic activity was then measured amperometrically. Figure 2 shows the substantial effect of CNT coatings on the performances of the electrodes. This effect is attributes to the catalytic contribution to the electrochemical reaction and the increase in effective electrode area.
Figure 3: Each dot represents 5 independent experiments. The experiments were carried out in 0.1M phosphate buffer pH 5.8 at 1.6mm-diameter gold electrode by applying 0mv vs. SCE.To conclude, We have shown that the sensor was able to detect CRP concentrations of several ng/ml. The range of which will provide clinically relevant diagnostic data (physiological plasma concentration of CRP is 0.8µg/ml). The system is in it's early optimization stage. Factors such as antibody concentration, incubation times, buffers pH are currently being investigated.
