Label-free Colormetric And Chemiluminescent Analysis Based On The Interaction Between Aptamer And Silver Nanoparticles

Silver Nanoparticles (AgNPs) has unique physical and chemical properties. In this thesis, colormetric and chemiluminescence detection methods have been studied and developed based on surface plasmon resonance (SPR) property and catalytic activity of AgNPs. The resulting methods have successfully been used for assaying adenosine, thrombin and IgE target biomolecules. The main reaserch contents are as follows:1. Label-free colormetric assay for the detection of biological molecules based on the interaction between aptamer and silver nanoparticlesIn this work, we have developed a colormetric assay method which can be used to determinate the biological molecules based on the aggregation of AgNPs in the high concentration of salt while the aptamer can protect AgNPs from aggregation. The adsorption of highly negatively charged aptamer on AgNPs increased their resistance to salt-induced aggregation due to the increased electrostatic repulsion between the silver nanoparticles. When the target molecule adenosine were added into the solution, however, the aptamer bound with the target and left the surface of AgNPs due to their high affinity for adenosine. In this case, the electrostatic repulsion of the AgNPs would decrease and thus their aggregating would happen when salt was added into the solution. The SPR absorption will significantly changed and could provide the quantitative results, which can be used for the detection of biological molecules. This method shows its more potential advantages such as automation and high-throughput. 2. Label-free chemiluminescent assay for the detection of adenosine based on the interaction between aptamer and silver nanoparticlesIn this work, we use the interaction between the aptamer and the target and the catalysis activity of AgNPs to enhance the chemiluminescence. The presented method was successfully used for the detection of adenosine. The adsorption of aptamer on the surface of AgNPs decrease the catalysis activity due to the catalytic reaction takes place on the surface of AgNPs. When adenosine was added into the solution, aptamer will bind with adenosine and left the surface of AgNPs, the catalysis activity restored, and the CL intensity increased. This method was proved high sensitivity and selectivity. In addition, it can be used for the detection of ions, small molecules, DNA and proteins.