Nanomaterials in electrochemistry: applications in biosensing

The detection of biological and chemical species is central to many areas of healthcare and the life sciences, ranging from uncovering and diagnosing disease to the discovery and screening of new drug molecules. Hence, the development of new devices that enable direct, sensitive, and rapid analysis of these species could impact humankind in significant ways. Devices based on nanomaterials are emerging as a powerful and general class of ultrasensitive sensors for the direct detection of biological and chemical species. Central to detection is the signal transduction associated with selective recognition of a biological or chemical species. Nanostructures offer new and sometimes unique opportunities in this rich and interdisciplinary area of science and technology. The diameters of these nanostructures are comparable to the size sof biological and chemical species being sensed, thus intuitively represent excellent primary transducers for producing signals that ultimately interface with macroscopic instruments. Metallic nanowires and nanostructured materials exhibit interesting properties that can be exploited for sensing. The investigation of biosensitive materials is a rapidly expanding field of research, dedicated for various applications in health-care industry, food quality control and environmental monitoring. The development of reliable electrochemical biosensors is a field of great importance in nowadays technology since they are very promising to replace a wide range of analytical techniques thanks to their properties and characteristics. A crucial problem in the commercial development of such biosensors is the ability to immobilize an enzyme on an electrode without any loss of its biological activity. Many methods have been proposed to overcome this problem, among which the use of self-assembling monolayer as anchor layers for the enzyme molecules has been extensively studied. However, if monolayers are used, only a very small amount of enzyme is immobilized and this will turn to a very low amperometric response of the biosensor. On the contrary, the use of nanomaterials as electrode provides a huge surface area per unit volume allowing the immobilization of a larger amount of enzyme. In this work we report the preparation and the fully characterization of gold nanowires arrays to be used for assembling of electrochemical biosensors. The immobilization of single or clustered molecules of enzymes such as glucose oxidase (GOD) and choline oxidase (ChOx) on the nano-structured surfaces could be an important step towards the development of biosensors based on direct electrochemistry.