Application of Polydopamine Functionalized Zinc Oxide for Glucose Biosensor Design

Zinc oxide (ZnO) nanostructures are widely used in optical sensors and biosensors. Functionalization of these nanostructures with polymers enables optical properties of ZnO to be tailored. Polydopamine (PDA) is a highly biocompatible polymer, which can be used as a versatile coating suitable for application in sensor and biosensor design. In this research, we have grown ZnO-based nanorods on the surface of ITO-modified glass-plated optically transparent electrodes (glass/ITO). Then the deposition of the PDA polymer layer on the surface of ZnO nanorods was performed from an aqueous PDA solution in such a way glass/ITO/ZnO-PDA structure was formed. The ZnO-PDA composite was characterized by SEM, TEM, and FTIR spectroscopy. Then glucose oxidase (GOx) was immobilized using crosslinking by glutaraldehyde on the surface of the ZnO-PDA composite, and glass/ITO/ZnO-PDA/GOx-based biosensing structure was designed. This structure was applied for the photo-electrochemical determination of glucose (Glc) in aqueous solutions. Photo-electrochemical determination of glucose by cyclic voltammetry and amperometry has been performed by glass/ITO/ZnO-PDA/GOx-based biosensor. Here reported modification/functionalization of ZnO nanorods with PDA enhances the photo-electrochemical performance of ZnO nanorods, which is well suited for the design of photo-electrochemical sensors and biosensors.

The Photoelectrochemistry of Assemblies of Semiconductor Nanoparticles at Interfaces

The application of photoelectrochemical methods presents the researcher with a powerful set of versatile tools by which photoactive materials, such as semiconductor quantum dots, at conductive interfaces may be interrogated. While the range of photoelectrochemical techniques available is quite large, it is surprising that very few have found their way into common usage within the nanoparticle community. Here a number of photoelectrochemical techniques and the principles upon which they are based are introduced. A short discussion on the criticality of ensuring the nanoparticles are reliably anchored to the substrate is followed by an introduction to the basic set of equipment required in order to enable the investigator to undertake such experiments. Subsequently the four techniques of transient photocurrent response to square wave illumination, photocurrent spectroscopy, intensity modulated photocurrent spectroscopy and intensity modulated photovoltage spectroscopy are introduced. Finally, the information that can be acquired using such techniques is provided with emphasis being placed on a number of case studies exemplifying the application of photoelectrochemical techniques to nanoparticles at interfaces, in particular optically transparent electrodes.