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PNA Microcontact Printing
case the signals are weaker, and this may be due to the steric hindrance of the surface, which
might be an important factor for long DNA sequences and could be more relevant if even
longer sequences are used.
5.2.4 PNA Microarrays fabrication by microcontact printing
The good results obtained by derivatizing surfaces using this technique, the short time
necessary to fabricate the devices, and the quality of the recognition process when PNAs were
linked to surface, led us to explore the possibility to couple µCP with an existing technology
in order to fabricate microarrays.
Figure 5-10: Fluorescence image (fluorescein dye) of PNA microarray fabricated via printing with a
flat PDMS stamp onto which a PNA array was spotted; aside the fluorescence intensity after 8
printing is reported.
As previously reported 5 , in fact, the application of microcontact printing in the fabrication of
microarray devices can make the process cheaper, more reproducible and less time
consuming. The system used to fabricate these devices is a commercial piezoelectric arrayer;
the fabrication of the device took place producing PDMS stamps having the same size of a
microarray slide without any pattern on the surface and gluing the oxidized stamp onto glass
slides in order to fit in the arrayer system. The stamps so modified were used as substrate for
PNA spotting. The stamp was inked with a PNA solution, dried for 15 minutes and printed
over glass slides derivatized with the aldehyde monolayer using 3 weights of 15gr each. The
slides were printed for 15 minutes and the same stamp was used to repeat the printing on
other slides without any further modification of the PDMS. The printing was repeated eight
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