Electrochemical Impedimetric Biosensors For Detection Of Liver Tumor Cells

Circulating Tumor Cells (CTCs) detach from the solid primary tumor into thebloodstream and may travel to different tissues of the body giving rise to metastasis.Although CTCs are very rare in the early stage of cancer patients, precise detectionof CTCs has been proven to significantly aid supervisory control of the patient’scondition and increase the possibility of positive prognosis. However, owing to therarity of CTCs in peripheral blood, detecting these cells requires methods combinedwith high sensitivity and specificity, which sets tremendous challenges for theimplementation of these assays into clinical routine. Recently, the development ofthe nanotechnology supplys a new opportunity for the CTCs detection. Among manydetection methods, the impedance-based biosensor exhibits many interestingfeatures such as label-free, direct detection of target through detecting the change ofimpedance. In this thesis, two types of impedance-based biosensors for the detectionof tumor cells were constructured based on the unique properties of nanomaterialsand antibody-antigen specific reaction:We presented a fast and simple impedimetric sensing approach for CTCsdetection. This device is based on a nanostructured architecture of carbon nanotubes(CNTs), which are assembled on ITO electrode surface. The binding of tumor cellsto anti-EpCAM causes the change of the resistance and the increase of resistancevalues is log-linear in the range of10to10~5cells per mL. The proposedimpedimetric sensing device allows for the sensitive and fast detection of cancercells from whole-blood samples without any further sample preparation steps.In addition, we developed a field effect transistor (FET) array immunosensorbased on gold nanorods (AuNRs). The use of DEP method make AuNRs withantibody molcules connected with each other in sequence between gold electrodes.In this paper, the influence factors of DEP are discussed in detaisl, and the FETarray are prepared and optimized successfully. The capture of tumor cells can lead tothe significant change of sensor resistance, and the resistance increase isproportional to the CTCs number. The array we proposed is high throughput andsensitive.