Nanomaterial based biosensors
II-8: Nanomaterial based biosensors |
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Chang Ming Li, |
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Abstract |
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Nanoscale materials are very attractive for the development of biosensors because of its capability to provide strong electrocatalytic activity, stability and minimize surface fouling of the sensors. In our research, different nanomaterials including nanocarbontubes, nanomagnetic beads and nanocomposite were used to develop highly sensitive and robust biosensors.
In one of our research, magnetic nanoscale beads were immobilized by galactosidase, an enzyme label for a highly sensitive and rapid electrochemical immunoassay sensor. The sensor was constructed with coupling redox cycling at interdigitated electrode arrays (IDA). The IDA device were fabricated with 3D structure, in which a 2.4 mm gap allows the nanomagnetic nanoparticle-attached enzymes close to the sensing electrodes and detection took less than 1 min with a limit of detection of 70 amol of b-galactosidase. This is very fast and sensitive sensors in comparison to conventional biosensors.
Nanocarbon particles were used to make composite electrodes for biosensors. Carbon/Teflon composite electrodes modified by glucose oxidase, Nafion and Os(bpy)3+2/+3 for glucose sensors. The sensor has overcome the drawbacks of conventional glucose sensor with problems of enzyme leaching and negative effect of oxygen concentration. The sensor was measured in glucose solution and serum sample with good reproducibility. These nanostructure sensors also demonstrated high sensitivity and wider dynamic range of glucose detection. Nanocarbontubes (NCT) were used electrochemically to fabricate NCT/polymer composite for protein sensors. Experimental results show that the composite significantly improved the polymer stability for improvement of signal to noise ratio. In addition, the nanoscale materials provided high specific surface area that can generate high current density/apparent unit surface area for increase of density of reaction centers. Thus, the nanomaterial based protein sensor shows extremely high sensitivity of 1 fg/ml, which is much greater than conventional ELISA detection limit (10 pg/ml, the most commercially sensitive immunoassay methods). In summary, the experimental results in our research demonstrated that nanoscale materials have unique electronic and physical properties for biosensor applications. The nanosize can also provide perfect approach to make nanoscale sensor device for pervasive system. Most importantly, the nanomaterials can significantly improve the sensor sensitivity. |
