The Applications Of Chemiluminescence Functionalized Nanomaterials In Novel Biosensors

In this dissertation, the state of arts in the field of chemiluminescence (CL), CL biosensors, and the applications of CL functionalized nanomaterials in biosensors were reviewed. In recent years, chemiluminescence (CL) functionalized nanomaterials have received more and more attention because a single functionalized nanoparticle could bind thousands of CL reagent molecules, leading to excellent signal amplification. In our research group, a series of novel methods was developed for the preparation of various CL functionalized nanomaterials and nanocomposites including luminol and its derivatives functionalized gold nanomaterials, luminol functionalized silver nanoparticles, luminol functionalized silver/graphene oxide composite(Ag/GO), N-(Aminobutyl)-N-(ethylisoluminol) and hemin dual-functionalized graphene hybrids. This new type of various CL functionalized nanomaterials and nanocomposites would be used as signal reporters for nucleic acid analysis and immunoassays with excellent signal amplification, improving the sensitivity of the bioassays. The aim of this dissertation is to explore the applications of chemiluminescence functionalized nanomaterials in novel DNA sensors and immunosensors. Based on N-(Aminobutyl)-N-(ethylisoluminol) functionalized gold nanomaterials, a sandwich-type electrochemiluminescence (ECL) DNA sensor and a label-free ECL aptamer sensor were developed for tuberculosis diagnosis and thrombin determination; Using luminol functionalized silver nanoparticles as labeling, a novel immunoassay based on competitive reaction was developed for sensitive detection of small molecules chloramphenicol; Based on luminol functionalized silver/graphene oxide composite (Ag/GO) and N-(Aminobutyl)-N-(ethylisoluminol) and hemin dual-functionalized graphene hybrids, a novel label-free aptasensor for2,4,6-trinitrotoluene (TNT) detection was developed. The main results are as follows:1. An effective sensor for detecting sequence-specific DNA from MTB was developed based on ABEI-AuNPs labeling. The DNA sensor exhibited excellent ECL response with a double step potential in CBS containing1.75x10-3M of H2O2. The sequence-specific DNA from MTB in range of1.0x10-15-1.0x10-12M can be detected by use of the ECL intensity with a considerably low detection limit of3.3x10-16M, which is superior to the previously reported methods without PCR amplification for the determination of MTB. Being challenged in real serum samples, this proposed method also shows an excellent capability for the determination of the target DNA from MTB. The proposed sensor is simple, rapid and reliable. It is also of a great advantage in terms of sensitivity and cost because of great signal amplification of ABEI functionalized gold nanoparticles, simple labeling procedure, and easy construction of the sensor. It is of great application potential for rapid diagnosis of TB in clinical fields.2. A competitive immunoassay for sensitive detection of small molecules CHL was developed using the luminol functionalized silver nanoparticles as nanoprobe for the first time. CHL in a range of1.0x10-8-1.0x10-6g mL-1could be detected by use of the CL intensity with a low detection limit of7.6x10-9mL-1.The labeling procedure is simple and fast, superior to all the previously reported labeling procedures. Since the labeling of small molecules is very difficult work, the present work provides a novel and effective labeling strategy for CHL. The immunoassay is simple, fast, cost-effective, sensitive and selective.3. An ECL bioassay based on dynamic interaction of aptamer, thrombin and ABEI-AuNPs for the detection of thrombin has been developed. The presented ECL bioassay is sensitive, specific, simple and fast. It exhibits a wide dynamic range from1.0x10-12-1.0x10-9M with a low detection limit of3.8x10-13M, which is superior to most previously reported label-free aptamer-based bioassays for thrombin. Moreover, the interfering species in the matrix can be well separated from the detection system by simply washing the electrode during the dynamic interaction. Thus the method is of high sensitivity and small matrix effects since many substances in the matrix could enhance and inhibit the CL of luminol and analogues leading to the interference. It has been successfully applied to the detectionof thrombin in real human serums. This work provides a new way to design aptamer-based protocols for the determination of bio-logically important substances. In principle, the proposed strategy might also be applicable for the determination of other biologically important substances by using corresponding aptamer.4. A label-free electrochemiluminescence aptasensor for2,4,6-trinitrotoluene detection was proposed based on an assembly strategy of luminol functionalized silver/graphene oxide composite(Ag/GO) and N-(Aminobutyl)-N-(ethylisoluminol) and hemin dual-functionalized graphene hybrids. It exhibits a wide dynamic range from1.0x10-12-1.0x10-9g/mL with a low detection limit of6.3x10-13g/mL, which is superior to most previously reported bioassays for TNT. The proposed aptasensor has some advantages such as simple operation, high sensitivity, no need of complex labeling and purification steps, making this methods time-saving and easy automation. Due to the wide target recognition range of aptamer, this strategy provides a promising way to develop new aptasensor for other analytes.