The Research On Piezoelectric Immunosensors Based On Novel Immobilization Material

Piezoelectric acoustic wave immunosensing technique, which incorporates high sensitivity of piezoelectric response and high specificity of antibody-antigen immunoreactions, is sensitive to multiple signals such as the surface mass, and the density, viscosity, conductivity, and dielectric effect of the test solution. It shows some outstanding advantages including simple-design, rapid response, high sensitivity, wide detection range, real-time digital output, and free from tracer labeling and sample purification etc. This kind technique may breakthrough some bottlenecks of the traditional analytical methodologies, showing an attractive future of potential applications in the biochemical diagnosis of clinical diseases. In the past few years, nanomaterials have been widely researched and used. Applying nanomaterials for the fabrication of biosensors will greatly improve the performance of the resulting biosensor. This research prepared many nanomaterials with different morphology, taking advantage of the good physical, chemical, electrocatalytic and biocompatibility of these nanomaterials and using them for the preparation of sensors. A series of piezoelectric immunosensoes for the determination of some tumor marker including CA15-3, CA125, AFP etc. is developed. The detailed materials are shown as follows:(1) A biomolecular immobilization strategy based on the adsorption of GNP- CaCO3 hybrid material has been proposed (Chapter 2). Gold nanoparticles (GNP) were assembled on the surface of porous calcium carbonate microparticles (CaCO3) in a neutral aqueous solution through electrostatic interaction. The GNP- CaCO3 has been characterized by the SEM and TEM measurements. The resulting GNP- CaCO3 hybrid material was used to offer a template for CA15-3 antibody immobilization. Comparing with those with antibodies immobilized by using GNP alone, that the developed sensing interface has some advantages such as high-sensitivity. good-reusability. The as-prepared immunosensor can allow for the determination of CA15-3 in the concentration range of 8.0～266.0 U mL-1.(2) An antibody immobilization strategy based on the nanogold-hydroxyapatite (GNP-HA) hybrid material has been proposed for the fabrication of piezoelectric immunosensor (Chapter 3).The detection performances of the resulting immunosensor were investigated by use of the antibody-antigen model system ofα-Fetoprotein (AFP). The hybrid material was characterized by the UV-vis spectroscopy,the scanning electronic microscope (SEM) and transmission electric microscope (TEM) measurements. Compared with immobilization procedures using only GNP or HA, the new GNP/HA hybrid material-based one can exhibit better performances for the immunosensor including specificity, reusability, and detection range of detection. The AFP can be linearly determined in the range of 15.3～600.0 ng mL-1.(3) A reversible piezoelectric immunosensing diagnosis technique has been proposed for the detection of tumor maker of CA125 (Chapter 4). The hydroxyapatite /chitosan nanocomposite(HA/CS)has been synthesized and characterized. The piezoelectric crystals were modified with the HA/CS nanocomposite and further assembled nanogold for removable adsorption of CA125 antibody. The assembly process and conditions were studied using the real-time-output device. The immunosensor with the proposed immobilization procedure shows some advantages, such as improved sensitivity due to the well-retained antibody activity and the significantly extended detection range, linear detection range of 15.3～440.0 U mL-1 for CA 125 detection.(4) A simple piezoelectric immunoagglutination assay has been proposed for rapid detection of human serum immunoglobulin G (Chapter5). Nanogold particles were used as replacements for the traditional latex to be labeled with sheep anti-human diagnosis serum (anti-IgG), the specific agglutination of the labeled nanogold particles in the presence of corresponding IgG was monitored by the sensing probe modified with BSA. It is found that the developed immunoaglutination assay is sensitive to IgG of the concentration as low as ~ 0.38μg mL–1, without need of immobilization of immunoactive entities. Results indicated that the analytical ability of the proposed piezoelectric technique is comparable to that of the ELISA method.