The Construction And Application Of Biosensors Based On The Water-soluble Conjugated Polymer And Aptamer

Conjugated polymers are characterized by their π-π conjugated system and delocalized electronic structures. These unique structure allow them strong ability to capture light. Conjugated polymers are described as “molecular wire”, which make them posses superior signal amplication. Compared to other fluorescent probes, such as small molecule and dyes quantums dots, watersolube fluorescent conjugated polymers have some advantages, such as good water-solubility, fine biological compatibility and low toxicity. Meanwhile, they can interact electrostatically with other opposite charged biological molecules owing to the modified side chain with cationic groups,, which makes it sensitively fluorescence quenching. According to these advantages, conjugated polymers are widely applied to biological detection, biological imaging, medical diagnosis and treatment. In this paper, different biosensors were designed by choosing appropriate cationic conjugated polymers as sensing materials and taking the negatively charged biomolecules(nucleic acid aptamer or adenosine triphosphate, etc.) as molecular recognition element to realize the sensitive, rapid and unmarked detection of different biomolecules.The main research work includes the following aspects:In the chapter 1, an aptamer biosensor has been developed based on the cationic conjugated polymers and aptamers to detect tumor markers. We Choose cationic conjugated polymers as fluorescent sensing materials and take the nucleic acid aptamer as molecular recognition element. When aptamer combines with polymer by electrostatic interaction, conjugated polymer occurs efficiently fluorescence quenching. When aptamer combines with its special tumor marker, making the aptamer be far from the cationic polymer, the polymer’s fluorescence turn on and the tumor markers are detected. The proposed sensor does not need any labeled probes, which can simplify the construction of the probes and detect the tumor markers rapidly and selectively.In the chapter 2, an aptamer biosensor has been developed based on the cationic conjugated polymers and aptamer to detect thrombin. It takes advantage of the feature of polymer “molecular wire” and the specific effect between aptamer and thrombin. When aptamer combines with polymer by electrostatic interaction, conjugated polymer occurs efficiently fluorescence quenching. When aptamer combines with thrombin, making the aptamer construction change from freedom state into G-quadruplex structure, which makes the aptamer be far from the cationic polymers, the polymers’ fluorescence turn on and thrombin is detected. The proposed sensor does not need any labeled probes, which can simplify the construction of the probes. This study offers a rapid, simple and selective method to detect thrombin.In the chapter 3, a simple and lable-free biosensor was designed to detect adenosine triphosphate(ATP) and acid phosphatase(ACP), which was based on the cationic water-soluble conjugated polymers. ATP could efficiently quench the fluorescence intensity of polymer due to the electrostatic interaction, so the designed method was successfully applied to the detection of ATP. In addition, ATP could be hydrolyzed by acid phosphatase(ACP) and lead to the recovery of the polymers’ fluorescence. The ACP can be detected through the fluorescence recovery degree.