Studies On The Ultrasensitive Electrochemiluminescence Immunosensors Based On TiO₂Nanotube Arrays

1gG is a kind of immune active globulin of the human body, the content of1gG is related to the body’s own autoimmune diseases and chronic diseases, so its detection has a strong clinical significance. The traditional immunoassays cannot undertake rapid and accurate quantitative determination. Therefore, it is necessary to develop sensitive, reliable, and low-cost sensing methods for clinical diagnosis. This paper will combine nanotechnology, immune analysis techniques and electrochemiluminescence technology to develop a series of novel, rapid, sensitive and high specific electrochemiluminescence immunosensor.In chapter1, a review is given to the principle and classification of immunosensor and the method of fixing biological molecules, the principle and characteristics of electrochemiluminescence and electrochemiluminescence immunosensor, the applications of the nanomaterials in immunosensor were summarized.In chapter2, we have developed for the first time a sensitive ECL immunosensor based on CdS NCs decorated TiO2nanotube arrays. Under the anodization in the experiment section a0.8μm-thick layer of aligned TiNT with openings of150±10nm was obtained. CdS nanocrystals (NCs) are decorated homogeneously on the T1O2nanotube arrays (TiNT) by chemical bath deposition method. The resultant CdS/TiNT composite shows largely amplified electrochemiluminescence (ECL) signals due to the vertically aligned nanotubular structure. The ECL intensity first increases with CdS film thickness, and the highest ECL intensity is observed on TiNT loading with CdS by10CBD cycles (CdS10/TiNT). The ECL intensity from CdS10/TiNT is about5-fold higher than that observed from the compact TiO2layer The ultrasensitive antigen detection is achieved on the composites via an efficient ECL quenching process introduced by sandwiched immunoreaction, and shows a detection limit of1.0fg mL-1. The results show that TiNT layers provide a convenient, low-cost, and sensitive platform for ECL immunosensing.In chapter3, a versatile electrochemical immunosensor based on TiO2nanotube arrays using a CdTe quantum dots (QDs) coated TiO2nanoparticle (TiNP/QDs) as a label was developed and it have been successfully used in the construction of signal amplification electrochemiluminescence immunosensor. In this strategy, TiO2nanoparticles were employed as the carriers for immobilization of CdTe QDs. Goat antirabbit IgG antibody was covalently bound to CdTe QDs coated TiO2nanoparticle (TiNP/QDs). TiNP/QDs as the immunosensing labels were attached onto the TiNT electrode surface through a subsequent "sandwich" immunoreaction. Due to signal amplification from the high loading of CdTe QDs,10.3and15-fold enhancements in electrochemiluminescent (ECL) and square-wave voltammetric (SWV) signals for IgG detection were achieved compared to the unamplified method. The detection limits for IgG were0.05and0.005pg mL"1for ECL and SWV measurements, respectively. The resulting versatile immunosensor realized the amplification of immune signal and possesses high sensitivity, satisfactory reproducibility and regeneration, and good precision.