Development of Specific Immobilization Method on Gold Surface and Its Application for Determining Cardiac Risk

C-reactive protein (CRP) has been regarded as a most valuable marker of inflammation that had been shown in prediction of multiple prospective blood vascular studies such as an incident myocardial infarction, stroke, peripheral arterial disease, and sudden cardiac death. A CRP detection system on a solid surface was developed using dual-antibody binding, which first antibody was immobilized by specific binding with Protein A via a fusion form with streptavidin. Second antibody bound with CRP was used for an electrochemical analysis on the gold chip surface. The fusion protein and antibodies could be successfully immobilized on the gold surface by strong biotip-streptavidin interaction as examined by surface plasmon resonance analysis. The result showed that the limit of detection has reached at 2 pg/mL. Precision is adequate, and the wide-range response was shown with the concentration of CRP between 0.01 pg/mL to 1 mg/mL. Signal difference for the same sample among different established chips is very low. Besides, the stable electrical signal was apparently maintained (similar to 88% of initial response) for 35 days after storage at 4 degrees C. This study provided a possibility for the development of portable chips for CRP detection, especially in the point-of-care use.