Bio-transistors and bio-sensors

DNA-based polymers are proposed to address the disadvantages of polymer electronics over traditional semiconductors. These new materials maintain the same properties as traditional polymers, but are readily available and environmentally friendly.

Professor S Hall

Over the last fifteen years studies have shown a wide diversity of uses of DNA as polymer with proven abilities for bio-polymer in electronics, wireless receivers and optics. The vast majority of this research has been performed in Japan and the USA. The main focus for the use of DNA as polymer so far has been on its optical properties, with the main emphasis on cladding of optical fibres. Although polymers are inherently soft and flexible, the use of DNA as the polymer allows cross-linkers to fix the position of the DNA inside the polymer fim, creating a solid cladding. Furthermore, double-stranded DNA allows so-called intercalators to be inserted within the helical structure of DNA. These intercalators have various properties for example intercalating dyes will alter the optical properties of the polymer. However, they do not alter the helical structure of the DNA and will not affect the robustness or flexibility of the polymer film. When looking at the electrical properties of the DNA-biopolymer, there is less research to refer to.  

At the moment, the work reported in the literature deals with the resistive properties of the polymer. More relevant is work done on bio-field effect transistors where the transistor characteristics of the DNA-polymer were studied both on its own and also doped with other materials, ranging from nanoparticles to carbon nanotubes to other conducting polymers.  This work showed that apart from using intercalators it is also possible to insert other molecules/polymers into the DNA matrix in order to alter the electrical properties of the DNA-polymer. The current state-of-the-art with respect to electrical properties of DNA-polymer devices is the ability to measure. However, the understanding of what governs the charge transfer in the device is completely unknown. The present project will entail systematic study of the processing parameters, physical and electrical properties of DNA-based bio-polymers, in view of engineering the conductivity of these layers for bio-transistors and bio-sensors applications.

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