The remarkable electrocatalytic properties and small size of carbon nanotubes make them ideal for achieving direct electron transfer to proteins, important in understanding their redox properties and in the development of biosensors. Here, we report shortened SWNTs can be aligned normal to an electrode by self-assembly and act as molecular wires to allow electrical communication between the underlying electrode and redox proteins covalently attached to the ends of the SWNTs, in this case, microperoxidase MP-11. The efficiency of the electron transfer through the SWNTs is demonstrated by electrodes modified with tubes cut to different lengths having the same electron-transfer rate constant.

The modification of an interface on a molecular level with more than one molecular −building block× is essentially an example of the −bottom ± up× fabrication principle of nanotechnology. The fabrication of such integrated molecular systems in electrochemistry has seen rapid progress in recent years via the development of sensing interfaces fabricated using self-assembled monolayers (SAMs). This review outlines recent advances and applications of selfassembled monolayers for modifying electrodes with an emphasis on the development of integrated molecular systems. First, some basic issues regarding fabricating integrated molecular systems, such as the role of the surface topography of the electrode and patterning surfaces, are discussed. Subsequently an overview of recent developments in pH, inorganic and bio sensing involving the use of SAMs is given. Finally emerging trends in using molecular building blocks in the fabrication of integrated molecular systems, such as nanotubes, dendrimers and nanoparticles, are reviewed.

Hybridization-induced physical changes of DNA are exploited in the development of DNA switchable surfaces for electrochemical biosensing purposes. Two types of biosensing concepts are explored, both based on the same basic switchable surface. The interface is designed so that the end-tethered DNA is able to switch from a flexible state to a rigid one upon hybridization. The first biosensing concept described is a label-free system that uses air oxidation of the interface, followed by the change in accessibility of the surface upon hybridization to detect complementary target DNA. The second is a ferrocene-labeled system exploiting the change in DNA flexibility alone. Atomic force microscopy studies of the DNA switching surface are described.

A label free electrochemical method of detecting DNA hybridisation is presented based on the change in flexibility between a single strand of DNA and a duplex causing an ion-gating effect where hybridisation opens up the electrode to access of ions.