Electrochemical paper-based immunosensor for biomarkers detection

This dissertation focused on the development of electrochemical paper-based immunosensor for determining essential biomarkers by using a label-free immunoassay. This dissertation can be divided into four main parts. In the first part, an origami paper-based analytical device (oPAD) was developed for c-reactive protein (CRP) detection. oPAD was designed to combine the preparation of immunosensor and detection step into a single device. A gold nanoparticle modified graphene screen-printed carbon electrode (AuNPs/G/SPCE) was utilized to enhance the sensitivity of the electrode. The developed sensor was successfully applied to determine CRP in a certified serum sample. For the second part, an electrochemical paper-based analytical device (ePAD) was created for simultaneous determination of three crucial cardiovascular disease (CVD) biomarkers including CRP, troponin I (cTnI), and procalcitonin (PCT). The proposed ePAD has multiple detection zones and multiple working electrodes, which could enable simultaneous three biomarkers in a single sample with high sensitivity and selectivity. For the third part, a simple and low-cost ePAD immunosensor for ferritin determination was reported. The ePAD was custom designed on the filter paper to successfully fabricate an immunosensor. The working electrode was first modified with graphene oxide (GO) using an inkjet-printing technique to enhance the reproducibility of the electrode. The ePAD was finally applied in a practical sample, giving results that are in agreement with the standard method. Lastly, an ePAD was architecturally designed for simultaneous detection of hepatitis B (HBV) and hepatitis C core antigen (HCV). The fast-flow and delayed channels were created to control the flow velocity on an ePAD device. To validate the sensor performance, the developed immunosensor was applied to measure the known amount of HBV and HCV in the serum samples. All developed immunosensors provided good performances for biological and clinical diagnosis and allowed for further development of an advanced platform.