Genosensors fabrication

Physical or electrochemical adsorption uses non-covalent forces to affix the nucleic acid to the solid support and represents a relatively simple mechanism for attachment that is easy to automate. Adsorption was favoured and described in some chapters as suitable immobilization technique when multisite attachment of DNA is needed to exploit the intrinsic DNA oxidation signal in hybridization reactions. Dendrimers such as polyamidoamine with a high density of terminal amino groups have been reported to increase the surface coverage of physically adsorbed DNA to the surface. Furthermore, electrochemical adsorption is described as a useful immobihzation strategy for electrochemical genosensor fabrication. 

One crucial and hence central step in the design, fabrication and operation of DNA chips, DNA microarrays, genosensors and further DNA-based systems described here (e.g. nanometer-sized DNA crafted beads in microfluidic networks) is the immobilization of DNA on different soHd supports. Therefore, the main focus of these two volumes is on the immobilization chemistry, considering the various aspects of the immobihzation process itself, since different types of nucleic acids, support materials, surface activation chemistries and patterning tools are of key concern. 

There are numerous film-fabrication methods available, depending on the film material. The two most common materials used for the fabrication of thick- and thin-film electrodes used as support/detector in genosensor devices found in the literature are gold and carbon,... 

As it has been shown in previous sections, the use of thick- and thin-film electrodes as supports for genosensor devices offers enormous opportunities for their application in molecular diagnosis. The technologies used in the fabrication of both thick- and thin-film electrodes allow the mass production of reproducible, inexpensive and mechanically robust strip solid electrodes. Other important advantages of these electrodes are the possibility of miniaturisation as well as their ease of manipulation in a disposable manner and therefore the use of small volumes. This is an important issue that makes this methodology for detection of DNA more attractive. 

Electrochemical genosensors are based on electrochemical transduction to detect the hybridization event. The immobilization of DNA onto the electrodes plays an important role in the fabrication of DNA electrochemical biosensors. 

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