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Cystic Fibrosis spin valve based gene chips
By the end of 2005, INESC MN had completed its third generation biochip using 24 spin valve based probe sites. This chip was used in the context of the EC CF Chip project to test CF gene mutations (see Fig.1). A patent was deposed underlying the principle of magnetically assisted hybridization using U-shaped current lines to drag target biomolecules over the sensor site, and U-shaped spin valve sensors to detect hybridized targets aftdsr the proper washing cycles. The chip was tested using 2um and 250nm diameter magnetite particles (Micromod). For the 250nm labels, the chip was able to read from single labels up to about 3200 labels. Biotinilated probes were used (80mers) immobilizred on a silanized SiO2 surface, and targets were labeled with streptavidin coated 250nm diameter magnetic nanoparticles.
Fig.1-24 probe spin valve based biochip using U-shaped current lçines and spin valve sensors.
Fig.2 show results for CF gene mutation detection ( average over 16 probe sites).
Fig.2 Hibridization results for a complementary probe (rp29), a non-complementary probe ( asah), and no probe. Notice more than 10:1 signal between the complementary and non-com,pementaery probes.
The success of this chip was instrumental on the approval of the SNIP2CHIP project where a similar architecture will be used for SNIP detection in Cystic Fibrosis.