Developments in Nanobiosensors at ANIDecember 1, 2006 By: Peter Adrian
This content is excerpted from Sensor Technology Alert and Newsletter, a sensor intelligence service published by the Technical Insights unit of Frost & Sullivan.
A core technology developed by Austin, Texas-based Applied Nanotech Inc. (ANI) is the firm's innovative nanobiosensor technology. The sensing elements in this device consist of nanoscale composites: substrates with a nanomaterial, such as carbon nanotubes (CNTs) and other nanoparticles, are combined with a conducting polymer and biological elements, including enzymes, antibodies, and nucleic acids. The developed sensors have a silicon substrate base on top of which layers of chromium and gold are deposited using vacuum deposition techniques; and finally, a paste of carbon nanotubes is dispensed on to the surface of the metal. An electropolymerization process is used to deposit a conducting polymer onto the CNT paste, followed by immobilization of biological enzymes on the surface. According to ANI, each of these processes is novel.
Sensing occurs when a biochemical reaction takes place between the gases being sensed (which may take a variety of forms, ranging from toxic gases to chemical or biological weapons). The sensor then triggers electrons, which are in turn converted into an analog signal. In response to an applied cyclic voltammogram, the oxidation of the analyte species (that is, the gas or pathogen being sensed) at the CNT-conjugated polymer biological enzyme interface would be represented by a peak current, a response that is caused by the electrons generated from a biochemical reaction between the analyte and electrode.
According to ANI executives, their nanobiosensor technology has a number of application-level benefits, which include miniaturization and multiplexity to a degree suitable for applications in defense; a reduced probability of false positives and false negatives; an improvement in sensitivity and selectivity in comparison with current sensors; and rapid recovery times.
As of now, a broad range of applications has been defined for the technology. This includes environmental applications (where they can help detect hazardous chemicals, such as polyphenols, sulphites, peroxides, and formaldehydes); healthcare; biological warfare, where toxic gases and pathogens can be monitored; immunosensors; DNA biosensors; and in the food industry. A number of these applications point to potential uses in the defense and homeland security sectors.
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