The Constructions And Applications Of Biosensors Based On Nanomaterials And Small Molecules

Nanomaterials have special structure, which results in series of interesting physical and chemical properties. So their applications toward electrochemical sensors and biosensors have gained interest. Firstly, this thesis was focused on the new nanocomposites which were developed by combination of multiwalled carbon nanotubes (MWNTs) and nanoparticles. Glucose biosensors were then constructed by these nanocomposites, and their electrochemical properties had been explored. Secondly, the self-assembled nanocomposite was formed by MWNTs and biopolymer, and was used to study the electrochemical properties of NADH. And finally, the modified electrode which was formed by immobilizing small molecular onto electrode surface, was used to detect dsDNA in the solution. The main points of this thesis are summarized as follows:1. A new nanocomposite was developed by combination of prussian blue (PB) nanoparticles and multiwalled carbon nanotubes (MWNTs) in the matrix of biopolymer chitosan (CHIT). The PB and MWNTs had synergistic electrocatalytic effect toward the reduction of hydrogen peroxide. The CHIT/MWNTs/PB nanocomposite modified glassy carbon (GC) electrode could amplified the reduction current of hydrogen peroxide by ~35 times compared with that of CHIT/MWNTs/GC electrode and reduce the response time from ~60 s for CHIT/PB/GC to 3 s. Besides, the CHIT/MWNTs/PB nanocomposite modified GC electrode could reduce hydrogen peroxide at a much low applied potential and inhibit the responses of interferents such as ascorbic acid (AA) uric acid (UA) and acetaminophen (AC). With glucose oxidase (Gox) as an enzyme model, a new glucose biosensor was fabricated. The biosensor exhibited excellent sensitivity (the detection limit is down to 2.5μmol L-1), fast response time (less than 5 s), wide linear range (from 4μmol L-1 to 2 mmol L-1) and good selection.2. A new nanocomposite material for construction of glucose biosensor was proposed. The biosensor was formed by entrapping glucose oxidase in CHIT/nanoporous ZrO2/MWNTs nanocomposite. In this biosensing thin film, MWNTs could effectively catalyze hydrogen peroxide and nanoporous ZrO2 could enhance the stability of the immobilized enzyme. The resulting biosensor provided a very effective matrix for the immobilization of glucose oxidase and...