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Studies On Amperometric Immunosensor For Carcinoembryonic Antigen And Auman Chorionic Gonadotrophin Based On Nano-materials

Posted on:2012-10-08Degree:MasterType:Thesis
Country:ChinaCandidate:P LvFull Text:PDF
GTID:2178330335956089Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Electrochemical immunosensors, which combined the merits of electrochemical technology and immunoassay, due to their high sensitivity, fast analytical time, and simple measurement, low-cost and high selectivity, have been applied to a wide range of analytical areas, including bioassay, clinical diagnosis and environmental monitoring, As for the construction of an electrochemical immunosensor, the key factor is the method and material used to immobilize biomolecules. Nano-materials, which exhibiting large specific surface area, strong adsorption capacity and good biocompatibility, are favourable for constructing biosensors, which not only retain the biological activities of biomolecules, but also enhance the sensitivity and service life of the sensors. In this paper, we fabricated some immunosensors biomimetic interface combining several nano-materials with gold nanoparticles, platinum nanoparticles, and carbon nanotubes for the immobilization of biomolecules. In this article, the immunosensor assembly processes have been studied, and characterization of the sensor have been evaluated, the results show that the sensitivity and stability of the sensor, in a certain extent, have been improved, and the sensor is simple to prepare and operate. The main works are included as follows:1. A Novel Immunosensor for Carcinoembryonic Antigen Based on Prussian Blue Nanoparticles Composites and Gold NanoparticlesPB nanoparticles, as an electron transfermediator, have been cast onto a glass carbon electrode surface using chitosan (CS) and poly(diallyldimethylammonium chloride)(PDDA) as protective matrix and Carbon nanotube as the carrier. The high surface area is propitious to the immobilization of PB and promotes electron transfer between redox center of PB and electrode surface, which will improve the sensitivity and stability of biosensor. GNPs were then attached onto the electrode through the electrostatic interaction between cationic PDDA and negative GNPs and strong binding interactions between GNPs and the amino groups of CS. Then, the carcinoembryonic antibody (anti-CEA) was adsorbed onto the surface of modified electrode. In this experiment, the immunosensor is simple to prepare, exhibited high selectivity, long-term stability and displayed high sensitivity, broad linear range and low detection limit for CEA determination.2. Amperometric Immunosensor for Carcinoembryonic Antigen Based on Gold Nanoparticles and L-cysteine@ferrocene functionalized chitosan CompositeFerrocene-monocarboxylic and L-cysteine were crosslinked by EDC·and NHS. then L-cysteine@ferrocene functionalized chitosan (Fc@CSSH) could be synthetized by the formation of and the carboxyl of L-cysteine@Fc hybridized materials amide bond between the amino of CS, which formed the functional biomembrane with good redox electrochemical activity and active groups (thiol group and amino group). Nano gold can be adsorbed to the electrode surface by the active groups, and then anti-CEA was adsorbed to prepare carcinoembryonic antigen immunosensor. In addition to GOD was employed as blocking agent instead of BSA, which could amplify the response of antigen-antibody interaction and could result in higher current response because of the electrocatalytic characteristics of GOD for glucose. The change of DPV peak current of the proposed immunosensor was proportional to the CEA concentrations in the linear range from 0.05 to 100 ng/mL with the detection limit of 0.02 ng/mL.3. An Immunosensor for Human chorionic gonadotrophin Based on Horseradish peroxidase-platinum nanoparticles as Label.A highly sensitive amperometric immunosensor for detection of HCG based on PtNPs and enzyme as signal amplified labels to label secondary antibody. Functional multi-walled carbon nanotubes (MWCNTs) and nano-Au were modified on the electrode, which can facilitate to electron transfer and excellent biocompatibility and increased the amount of antibody due to its higher exposed surface area. Then, the electrode was incubated with anti-HCG, HCG and reacted with the secondary antibody which was labeled by HRP and nano-Pt. Nano-Pt and HRP induced catalytic oxidation of H2O2, which could results in the great amplifition of current signal and the increase the of mmunosensor sensitivity. Moreover, the immunosensor exhibited high selectivity, good stability.
Keywords/Search Tags:Carcinoembryonic antigen, immunosensor, gold nanoparticles, Multi-walled carbon nanotube, Human chorionic gonadotrophin
PDF Full Text Request
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