Polypyrrole and its nanocomposite based electrochemical immunosensors

• Main Author: Chen, Wei
• Other Authors: Li Changming
• Format: Theses and Dissertations
• Language: English
• Published: 2008
• Subjects: DRNTU::Science::Medicine::Biosensors; DRNTU::Science::Chemistry::Organic chemistry::Heterocyclic compounds
• Online Access: https://hdl.handle.net/10356/12889
• Institution: Nanyang Technological University

The goal of this research is studies of polypyrrole (PPy), polypyrrole propylic acid (PPa) and PPy nanocomposite based electrochemical immunosensors for high sensitivity and good specificity. The nanocomposite was electrochemically one-step synthesized to incorporate gold nanoparticles and PPa into PPy matrix for significantly improving the stability and electroactivity of the film. In situ atomic force microscopy (AFM) associated with simultaneously electrochemical measurements was employed to study the nucleation and growth process and a mechanism is proposed accordingly. An impedimetric immunosensor based on the nanocomposite was designed and fabricated, and a novel data processing method was investigated. Normalized impedance was introduced to present the unit impedance change for reducing the variation of the bulk electronic properties of Ab/PPy films and then improving the signal to noise ratio (S/N). PPa as a component in the sensing composite film provides high porosity and hydrophilicity for sensitivity enhancement, while introducing high density of carboxyl groups of PPa for covalent immobilization of protein probes, leading to significantly improved detection sensitivity compared with conventional entrapment methods. As a model, anti-mouse IgG was covalently immobilized or entrapped in the PPa film and used in a sandwich-type alkaline phosphatase-catalyzing amperometric immunoassay with p-aminophenyl phosphate as the substrate, demonstrating remarkable improvement of the immunoassay sensitivity.