Research On Amplification Effect By Nanocomposites Labeled Signaling Molecules And Construction Of Biosensors

The determination of tumor markers in their early development stage plays animportant role in screening for a disease, in diagnosing a disease, and in determining theprognosis of a disease. It also offers opportunities for understanding fundamental biologicalprocesses involved in disease progression and monitoring patient responses to therapymethods. At present, the health departments all over the world have considered the accurateanalysis of cancer markers as the primary task. To achieve an early, accurate and rapiddetection of cancer, countries biologists, medical scientists and technology workers arepaying more attention on developing more effective methods. However, it is often notapplicable to use traditional detection methods in developing countries and resource-poorcountries and regions, because these analytical systems are too expensive, large,complicated, and dependent on specific infrastructures and professional operation personnel.Therefore, it is of considerable interest to the further research for rapid, simple, sensitiveand accurate alternative methodology for determination of tumor markers.In this paper, to reliaze the point-of-care testing, rapid and portable determination ofcancer markers in the body fluid, we combine the applications of biosensors withnanotechnology in the bioanalysis to develop ultrasensitive biosensors. In addition, weintroduced photoelectrochemical (PEC) method into biosensors. And homemade portabletransformers and multi-channel multiplex switch were combined to develop low-cost,high-throughput real-time detection system. The main research is as follows:(1) ZnO nanorods inorganic-organic heterostructured light-emitting diodes have beendemonstrated on a cheap/disposable paper substrate and applied in multiplexed PECimmunoassay. Coupling photoirradiation with electrochemical detection, PEC sensors havethe advantages of both optical methods and electrochemical sensors. Benefiting from thedifferent energy form of the excitation source (light) and detection signal (current), in thePEC detection process, some undesired background signals are reduced and high sensitivityare achieved. The light source with the advantages of portable, low-cost, and easy to fold,will have a broad prospect in future analysis applications. (2) An easy approach was reported to synthesize graphene nanosheets attached to spikyMnO2nanospheres (GS/MnO2) which showed good catalytic activity, electrical conductivity,solubility and processability. After depositing a layer of AuNPs, it was used to immobilizeAb2. With a sandwich-type immunoassay format, the amount of GS/MnO2labeled Ab2wentup with the increased concentration of antigens in the sample. In the experiments, H2O2could be catalyzed by MnO2to generate O2, then O2would react with S2O82-to producelight. Such immunosensor exhibited high sensitivity in the detection of carcinoembryonicantigen in serum samples. Therefore, the proposed method provides a new promisingplatform of clinical immunoassay for other biomolecules.(3) Using carbon quantum dots@SiO2as labels, a novel electrochemiluminescence(ECL) immunosensor array for the sequential detection of multiple tumor markers wasdeveloped by site-selectively immobilizing multiple antigens on different electrodes. TheECL signal from different immunosensors was collected in turn by a photomultiplier withthe aid of a home-made potential transformer equiped with a home-mademultiplexed-switch. The results for real sample analysis demonstrated that the newlyconstructed immunosensor array provided a rapid, simple, simultaneous multi-analyteimmunoassay with high throughput, cost-effective and sufficiently low detection limits forclinical applications.(4) A novel ECL immunosensor for sensitive detection of human chorionicgonadotrophin antigen (HCG-Ag) has been developed by successfully combining Fe3O4/CSMNPs and QDs@PtRu with attractive features. The immunosensor could be convenientlyaggregated and separated through a magnet, which is of great need in clinical fields, sincethe aggregation could be used to gather HCG-Ag for detection, even when the concentrationis low.