Gold nanostructured surfaces for amperometric biosensors

Electrochemical sensors and biosensors attract the interest of scientific community due to the low cost and easy use. In many cases the electrochemical transducer consists of gold surfaces, chosen thanks to the high affinity toward many functional groups, such as thiol groups, which allows stable anchoring of suitable recognition elements. Hence, functionalisation of probe molecules with thiol terminal groups has become a fundamental step in the development of many sensors. In the present communication, we check the capability of amino terminal groups in achieving stable interactions with Au surfaces. With this aim, amino derivatives bearing a ferrocene terminal group as the redox probe have been employed. The stability of the adsorbed molecules on the surface and the reproducibility of the deposition procedure have been checked through electrochemical investigations. In order to maximise the number of recognition elements anchored on the transducer, the electrode surface can be nanostructured. For this purpose, electrochemical approaches, consisting of an electrochemical reduction of AuCl4- salt at a suitable potential, are generally followed. Here we report the advantages of using chemically synthesised Au nanoparticles for the construction of nanostructured surfaces. Au nanoparticles have been stably fixed on Au planar surfaces through dithiol Self Assembled Monolayer. The physico-chemical characteristics of the resulting Au nanostructure have been characterised by varying the deposition parameters, through electrochemical and impedance spectroscopy investigations.