DISSERTATION

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