Electrochemiluminescence Immunosensor Based On Zinc Oxide Nanostatic Amplification

Nanomaterials are widely used as biomarkers and biosensors because of their good biocompatibility and unique surface characteristics. Due to the controllable merits of electrochemical method, electrogenerated chemiluminescence (ECL) analysis has the advantages of little background, simply optical setup, high sensitivity, good reproducibility and good selectivity compared with the fluorescence analysis. In this thesis, the preparation and characterization of two kinds of zinc oxide (ZnO) nanoparticles with different morphology, water-soluble CdSe quantum dots (CdSe QDs), gold nanoparticles (AuNPs) and reduced graphene oxide (rGO) were investigated; the ECL sandwich-type immunosensor of the detection of a-fetoprotein (AFP) was developed.1. The water-soluble CdSe QDs and ZnO nanoparticles were synthesized by a simple method. These nanoparticles were characterized by IR, UV and TEM. QDs also could be easily biolabelled and immobilized on the electrode, which were promising for ECL bioassays. Due to their high surface area and high surface reaction activity, the ZnO nanoparticles not only accelerate electron transfer communication between protein and the electrode but also provide a friendly substrate for immobilizing antibodies and retaining their bioactivity. ZnO nanoparticles were employed as the carriers for immobilizing more CdSe QDs to label signal AFP antibody (Ab2), leading to an enhanced ECL signal. Under the optimal detection conditions, the ECL sandwich-type immunosensor had a linear response range of0.5ng mL-1to600ng mL-1. The ECL sandwich-type immunosensor showed a good reproducibility, stability and high sensitivity and could be used to detect AFP in practical samples.2. A simple and sensitive sandwich-type electrochemiluminescence immunosensor with tripropylamine (TPrA) as a coreactant for detection of a-fetoprotein (AFP) was constructed by using ruthenium polypyridyl complex-functionalized zinc oxide mesocrystals as bionanolabels. To design high performance electrochemiluminescence immunosensor, gold nanoparticles (AuNPs) dotted reduced graphene oxide (rGO)-chitosan composite was immobilized on the gold electrodes, which increase the surface area of the working electrode to load more amounts of the capture antibodies (Ab1). The AuNPs and rGO could accelerate electron transfer between the detection probe and the electrode. The large surface area of zinc oxide mesocrystals was beneficial for capturing high content ruthenium polypyridyl complex, leading to an enhanced ECL signal. The sandwich-type electrochemiluminescence immunosensor provided a good linear range from0.04to500ng ml-1with a low detection limit of0.031ng ml-1. The ECL sandwich-type immunosensor showed a good reproducibility, stability and high sensitivity and could be used to detect AFP in practical samples.