DISSERTATION
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_____________________________________________________________ Results and Discussion<br />
3.4.2 DNA microchip fabrication<br />
DNA chips are becoming tremendously important in diagnostics 2,3 . They allow for a<br />
simultaneous analysis of a large number of target molecules and have become a crucial tool in<br />
genomic analysis. The development of an electrochemically produced DNA microarrays may<br />
provide highly controlled surfaces complemented with low production costs and time.<br />
Therefore, the applicability of the developed potential-assisted immobilization technique for<br />
the production of DNA microarrays was investigated using a 32-electrode chip comprising of<br />
(70 × 70) µm 2 gold electrodes (Figure 3.49) by modifying the chip with two different DNA<br />
sequences.<br />
Figure 3.49. a-e) Schemes of the chip modification sequence: a) bare chip; b) after<br />
potential-assisted immobilization of columns (C) 1 and 2 with the FRIZ sequence; c)<br />
potential-assisted MCU passivation of C1 and C2; d) potential-assisted immobilization of<br />
C5 and C6 with an E. coli sequence performed after the potential-assisted cleaning; e)<br />
potential-assisted cleaning of C3 and C4 and subsequent potential-assisted MCU<br />
passivation of C3-C8; during each step the whole chip was exposed to each solution; f)<br />
scheme of the final chip modification with the region (a) representing ssFRIZ/MCUmodified<br />
electrodes, region (b) representing MCU-modified electrodes, region (c)<br />
representing E. coli/MCU-modified electrodes and region (d) representing ssFRIZ/E.<br />
coli/MCU-modified electrodes; picture of the chip with the zoomed picture of the 32<br />
electrodes (taken from ref. 100 ).<br />
3.4 Potential-assisted preparation of DNA sensors 91