Development Of Biosensors Based On Novel Nanomaterials And Their Applications In Biological Analysis

Biosensor is an analysis device which could be used to identification, signal conversion and detection for biologically active substances (such as enzyme, antibody, antigen). It is typically part in the fields of sensor, and it’s always regarded as a new comprehensive technology which combines with biology, chemistry, physics, computer science, etc. Compared with general chemical analysis method, the biosensor has advantages of high selectivity and sensitivity, fast data acquisition, and simplicity in use, so it has been widely used in biosciences, food, medicine and many other fields.The development of new materials and technology continuously improve the biosensor performance. Because nanomaterials have special advantages including quantum effect, small size effect and interface effect, they show remarkable application prospect in the field of biosensors. The appropriate use of nano-materials can not only solve the problem of immobolization of sensitive materials and regeneration of sensors, but also can enhance the sensitivity and selectivity of biosensors. Nano-materials have many important applications in electrochemical biosensor and fluorescent biosensor, which is the focus of this paper.The biosensors of this paper were constructed with silica nano-particles, gold nano-particles, and carbon nano-tubes. The nano-materials and biosensors were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), atomic force microscope (AFM) and Fourier transform infrared spectrometer (FTIR) on morphology. And the sensor modification process was characterized with impedance and cyclic voltammetry. Electrochemical method or fluorescence were used to realize the detection of several important biological samples and satisfactory results were obtained. The work furnishes new experimental basis for clinical research of related diseases such as Parkinson’s, cancer and so on, it also provides new methods for the biological analysis and clinic practice. Specific contents are as follows:Chapter1. Introduction In this part, the structure, principle, characteristics and classification of biosensor were introduced at first to give an outline of it. Then we gave a brief review of electrochemical and fluorescent biosensor, which are the main emphasis of our research. The classification, characteristics, preparation methods of nanomaterials were introduced briefly. We also summarized its application in the above two kinds of biosensors. Then we expounded the research significance of several important biological samples which are closely related with our research. At last, we point out the main work and meanings of this research paper.Chapter2. Three-Dimensional Ordered Macroporous (3DOM) Composite for Electrochemical Study on Acetylcholinesterase Inhibition Induced by Endogenous NeurotoxinIn this chapter, a novel electrochemical biosensor based on three-dimensional ordered macroporous composite was developed and used for acetylcholinesterase (AChE) inhibition assay. The composite was fabricated by electropolymerization of aniline in the presence of ionic liquid (IL) on a sacrificial silica nanospheres template to form IL-doped polyaniline (IL-PANI) film at first. After that, AuNPs were decorated on the IL-PANI film and the3DOM composite could be got (AuNPs/IL-PANI). The electrochemical biosensor presented effective immobilization for AChE and showed good electrochemical performance at the catalytic effect of AChE on the hydrolysis of acetylthiocholine (ATCh).(R)-NMSal is a kind of endogenous neurotoxins which can affect the activity of AChE. The biosensor was used to study the mechanism of this inhibition process and obtained satisfactory results.Chapter3. Functionalized Au-quantum Dot Biocomposite for Glycan Expression Assay on Living Cancer CellsIn this paper, a functionalized Au-quantum dot biocomposite (QDs-BSA-Au-mannose) was synthetized and used for glycan expression assay on living cancer cells. The{QDs-BSA-Au-mannose} biocomposite was fabricated by applying the bovine serum albumin (BSA) protected Au nanoparticles (AuNPs) as matrixes to load quantum dots (QDs) firstly. Then thiomannosyl dimer (thiol-derivatized mannose:[mannose-S]2) synthesized was then anchored to the Au-BSA matrix to get the composite. It can have competitive binding with cell surface mannose to concanavalin A (Con A), which was immobilized on the glassy carbon electrode (GCE). The detection of glycan expression on living cancer cells could be achieved through the determination of fluorescence in the solution after competitive reaction. The GCE used in the method could combine both the advantage of electrochemical characterization and high fluorescence efficiency of QDs. The average amount of mannose on each single cell surface was detected for QGY-7701and A549. The biosensor could be successfully applied to analyze glycan expression on living cells.Chapter4. Construction of a Novel Immunosensor for Calmodulin Based on Electrochemical Signal Amplification StategyWe report a novel electrochemical immunosensor for quantitative detection of calmodulin (CaM) in this chapter. First PDDA, AuNRs and Ab1were coated on the electrode in turn to obtain Abi modified GCE.{MWNT-Au-PAMAM-HRP-Ab,} composite was synthesized by modification of dentritic high-molecular compound-polyamidoamine(PAMAM) and AuNRs on MWCNT. The abundant amino of PAMAM and AuNRs played a crucial role in the immobilization of protein. The composite could also accelerate electron transition in the electrochemical detection. A sandwich format was used in the composite-based electrochemical immunosensor. The result presented a good linear relationship between CaM concertrations and current signals and a wide dynamic response range and low detection limit was exhibited in the immunoassay. The biosensor shows high sensitivity and good stability in the detection, it provides a new method for the biological sample detection.