Study On The Recognition For Some Saccharides And Hydrogen Peroxide By The Prussian Blue Analogue Nanoparticles Modified Electrode

Prussian blue (PB) is an inorganic polycrystal and has been widely used as an electron transfer mediator in the amperometric biosensors since its deposition on the surface of electrodes in 1978. However, the traditional PB modified electrodes are not stable in neutral and alkaline pH and the PB films resolve easily, which greatly limit their application. To solve this problem, a large number of PB nanoparticles have been synthesized with the stabilizers, such as PVP, PSS, PVA, and so on. These protective polymers could not only improve the stability of PB modified electrode in alkaline solutions, but also bring attractive properties to the nanoparticles. In addition, the cubic PB structure is not limited to the iron ion and combinations of several transition metal ions in different oxidation states such as Co, Ni, Cu, etc.. In this paper, FeCl3 and K4[Fe(CN)6] were used to synthesize PB nanoparticles protected by chitosan (CS) and poly(diallyldimethylammonium chloride) (PDDA). Furthermore, PB analogue nanoparticles also protected by both CS and PDDA were synthesized using Ce(NO3)3 and K4[Fe(CN)6]. Transmission electron microscopy (TEM), UV-Vis absorption spectroscopy and resonance Rayleigh scattering (RRS) technique were employed to characterize the PB and PB analogue nanoparticles.The main content and some conclusions of the thesis are as follows:1. Electrochemical recognition for sugars on the chitosan-poly(diallyldimethylammonium chloride)-Prussian blue /nano-Au/4-mercaptophenylboronic acid modified glassy carbon electrodeA new amperometric biosensor for the detection of sugars was prepared. A glassy carbon electrode was modified with PB nanoparticles protected by CS and PDDA and then gold nanoparticles were assembled onto the electrode followed by the assembly of 4-mercaptophenylboronic acid (MPBA) onto the surface of gold nanoparticles through a sulfur-Au bond to fabricate a self-assembled biosensor. The PB nanoparticles protected by CS and PDDA were characterized using TEM and UV-vis absorption spectroscopy. The characterization of the self-assembled electrode was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The pKa values of the MPBA monolayer before and after combining with sugars were determined. The fabricated electrode exhibited excellent performances for determining D(+)-glucose, D(+)-mannose and D(-)-fructose on the basis of the change in ip of the Fe(CN)63-/4- ion in the presence of sugars.2. Multilayer structured amperometric biosensor based on the self-assembling technique for recognition of sugarsPB nanoparticles protected by CS and PDDA were cast onto a glassy carbon electrode surface directly. And gold nanoparticles were then assembled onto the electrode through strong binding interaction between gold nanoparticles and amino groups of CS and electrostatic interaction between oppositely charged gold nanoparticles and PDDA. Following this, cysteamine hydrochloride (Cys) was assembled onto the gold nanoparticles through a sulfur-Au bond, further reacted with glutaraldehyde (Glu) via Schiff s base formation. Finally,3-aminophenylboronic acid (APBA) was immobilized to the surface of upper modified electrode. TEM was employed to characterize CS and PDDA protected PB nanoparticles (CS-PDDA-nano-PB). The properties of the modified electrode were characterized by CV and EIS. The pKa values of the APBA monolayer before and after combining with sugars were determined. The fabricated electrode exhibited excellent performances for determining D(+)-galactose, D(+)-mannose and D(-)-fructose on the basis of the change in ip of the Fe(CN)63-/4-ion in the presence of sugars. Based on this, a new biosensor for determining sugars has been developed.3. A new material based on nanostructured Prussian blue analogue film doped with Ce(III) for development of hydrogen peroxide sensorPB analogue nanoparticles doped with Ce3+, have been synthesized using CS and PDDA as protective matrix, which were cast onto a glassy carbon electrode surface directly. TEM, UV-vis absorption spectroscopy and resonance Rayleigh scattering (RRS) technique were employed to characterize CS and PDDA protected PB analogue nanoparticles. And the properties of this modified electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Compared with the bare glassy carbon electrode, the modified electrode exhibited excellent performances for determining H2O2 And the electrochemical behavior of H2O2 at the modified electrode was investigated by CV and differential pulse voltammetry (DPV). A good linearity was obtained in the concentration range of 5.0×10-5～1.4～10-2M with a detection limit of 8.21 x 10-6M under the optimum conditions.