Gold Nanotubes Arrays: application to enzyme biosensors

Recently we developed a new approach to synthesise[1] conductive nanostructured materials, using a template method (Fig. 1). An arrays of gold nanotubules were produced by template chemical synthesis where the metallic constituents grow inside the void spaces of nanoporous host materials. Though, there now exists a huge range of hosts, particle track-etched membranes (PTM) present a significant advantage because they lead to the production of nanomaterials with monodisperse diameters and lengths. With such properties, nanoporous PTM represent excellent templates for the preparation of controlled nanoscale materials. These tubular nanostructures present the potential applications because of their large surface area per unit volume, allowing the immobilisation of a large amount of enzyme. This should leads to an increase of the sensitivity[2] of the biosensors (the detection limit are much lower, 3 order of magnitude than the corresponding detection limits for a conventional macroscopic disk electrode). The aim of the present study is to investigate the possibility of fabricating a highly sensitive amperometric biosensor through the immobilisation of an enzyme within tubular nanostructures. In this work, GOD enzyme was used as a model enzyme system to demonstrate the concept of this new biosensors. We successively report on the different steps in the fabrication of GOD nano-electrodes arrays: ? the electroless synthesis method used for the elaboration of gold nanotubes and the influence of some experimental parameters on the morphology and size of the nanotubes; ? Secondly, the modification procedure of gold surfaces by self-assembling of NH2 -terminated thiols or COOH-terminated thiols and the enzyme immobilisation onto the preformed SAM are presented. ? The systems have been characterised (Fig. 1,2) by different experimental techniques at each step of the fabrication. Finally, the amperometric response to glucose of the different enzyme nano-electrodes has been measured and the effect of some fabrication variables on the electrical response was investigated.