Novel Biosensors Based On Nanogold Of Seminetwork-type And Hybrid Structure

Biosensors of higher qualitity are needed with the rapid development of science and technology and the expanding application of biosensor in environment, food, medicine, military. Much study have been done on designing biosensors which are simper, sensitive, stabile, with lower detection limit and cost. The introduction of nanomaterials are bringing biosensors a turning point, taking advantage of the good physical, chemical, electrocatalytic property, and biocompatibility. Accordingly, this research prepared some sort of nanomaterials with different morphology, using them for the fabrication of biosensors. Immobilizing pretein such as antibody and enzyme with different methold, the resulting biosensors response well, showing high sensitivity, low detection limit and fast reponse time. The details are as follows:(1) We have investigated a method of producing seminetwork-type Au nanoparticles labled by horseradish peroxidase (seminet-nanogold-HRP) with cross-linkers 1,6-hexananedithiol (HDT), forming seminet structure to increase the immobility of HRP. Compared with HRP labled Au nanoparticles without HDT, the sensitive amperometric sensor of H₂O₂ mediated by seminet-nanogold-HRP, which was successfully immobilized on gold electrode supported by thiol-tailed groups of HDT, was more steady with a better current response in the low H₂O₂ concentration, and the detection limit reached 0.08μM. Characterization of the seminet-nanogold- HRP was carried out using UV-visible spectroscopy and TEM. The study of the film was performed by electrochemical impedence spectroscopy, quartz crystal microbalance and cyclic voltammograms.(2)A biomolecular immobilization strategy based on the adsorption of GNT-CaCO₃ hybrid material has been reported. Gold nanoparticles were assembled on the surface of porous calcium carbonate microparticles(CaCO₃) through electrostatic interaction in the neutral aqueous,forming GNT-CaCO₃ composite. The resulting GNT-CaCO₃ was used to offer a template for CA15-3 antibody immobilization to construct immunsensors for detecting CA15-3 in human serum. Study result indicates that the as-prepared immunsensors response well with a detection range of 8.0～266.0 U mL-1 for CA15-3. (3)A antibody immobilization stragedy based on cells has been proposed. The piezoelectric crystal was modified with cysteamine to deposite yeast cells, on which PSA antibody was immobilized. Compared with the traditional glutaraldhyde immobilization approach, study results indicate the yeast cells could provide appreciate bio-sorroundings for antibody due to its good biocompatibility and"arm"-extended effect, thus the immune activity of PSA can be protected well. The results of the proposed immunoassay and the chemiluminescence immunoassay methold, a conventional method for serum analysis in this county, were in reasonable agreement, which indicate the developed immunoassay is reliable.