| Biosensors represent a most plausible and exciting application area for nanobiotechnology. Nanosensors based on advanced nanomaterials are expected to emerge in the marketplace in significant volumes over circa the next ten years. Sensors constructed at the molecular scale are promising and have proved to be extremely sensitive, selective and responsive. For example, the US Defense Department has been interested in such sensors for rapidly and accurately detecting small amounts of chemical or biological agents to allow soldiers to defend against chemical or biological attacks. Using Sensors in Medical Diagnostics In the medical diagnostics arena, nanotechnology-based biosensors could be used, for example, to replace more costly and tedious laboratory methods for monitoring a patient's blood for proteins, chemicals, and pathogens. Our goal is to build an interdisciplinary team based on the expertise developed on carbon nanotubes, to develop novel, rapid-response biochemical sensors selective for targeted chemical and biological molecules. Using Multi-Walled Carbon Nanotubes (MWNTs) and Substrates in Sensor Production At the National University of Singapore, We have utilized high-density well-aligned carbon nanotubes, which are multi-walled and vertically aligned on a large area of substrates, such as Ta, that can be readily synthesized. In particular, Ta plate was used as a substrate and a thin cobalt (Co) layer of 8 to 50 nm was coated onto the substrate as a catalyst by magnetron sputtering for the synthesis of MWNTs. The nanotubes prepared by this method have diameters of 200 nm to 400 nm and a length of about 10 µm, depending on the Co layer thickness and growth time. The Benefits of Using Multi-Walled Carbon Nanotubes (MWNTs) in Biosensors MWNTs and Ta substrates can be easily attached to the surface of a planar electrode using conductive silver paint as a biosensing electrode. Firstly, these MWNTs have a high electrochemically accessible surface area, high electrical conductivity, and useful mechanical properties for developing electrochemical sensors in selectively detecting uric acid (UA) in the presence of L-ascorbic acid (L-AA). Secondly, MWNTs can be used as a nonenzymatic sensor to detect glucose with high sensitivity and stability in alkaline medium. Thirdly, we have successfully constructed a hemin-modified MWNT electrode in the development of a novel oxygen sensor for working at a relatively low potential. Future Plans for Using Multi-Walled Carbon Nanotubes (MWNTs) in Making Biochemical and Contaminant Sensors In summary, we have developed a unique expertise in electrochemical bio-sensing using multi-walled nanotubes as electrodes. We have started to collaborate with Massachusetts Institute of Technology (MIT) researchers who have developed ordered nanotube arrays, chemically functionalized nanotubes, and sensors based on conjugated polymers. Hence, we will show how the combination of this expertise and these capabilities will make it possible to produce novel, state-of-the-art biochemical and contaminant sensors, based on an original concept of being able to selectively detect, in real time, a single chemical species down to nanomole concentrations. |