Biomedical Engineering Reference
In-Depth Information
Fig. 5.5.
Self-self hybridization of Cy3 and Cy5 labelled total RNA from MDA
breast cancer cells on a Corning 4K cancer array. The composite image combining
both colors of one of the 4 sub-arrays is shown on the left. Empty spots are from
channels that were either not used or filled with a DNA free solution to control for
channel cross-contamination. A correlation analysis of all spots in the array is shown
on the right
with the amount of mRNA present in the RNA sample for a given gene, which
can vary by up to 4 logs. A good array should be able to reflect this variation
in gene expression and reveal at least 2.5-3 logs of dynamic range.
5.7 Conclusion
The successful development of the microarray platform required a merging of
the latest technologies in chemistry and biology with those from physics and
engineering. At the basis was the classical robot equipped with novel pin-
tools to enable the significant growth and popularity of this new technology.
Whether DNA, protein, lipids, whole cells or small molecules, the pin-printer
has provided a platform from which new miniaturized assay chemistries, sur-
face treatments and detection systems could be developed. While definitely
not the most economic mode of printing large quantities of high density ar-
rays, it is still one of the most accessible technologies to researchers all over
the world to perform array-based experiments with relatively low capital in-
vestment.
Believing that an e
cient printing system is the key to success in high
density arraying, as many as twenty different companies emerged early on
to develop and commercialize array-printing instrumentation, varying from
manual tools and desktop spotters all the way to sophisticated clean room
sized industrial printing presses. Given the typical cost of several hundred
U.S. dollars for a commercial expression microarray, for example, there ap-
pears to be a significant 'home-brew' arraying market. Yet, the recent wave
of consolidations, buy-outs and even business closures of printer (as well as
array) manufacturers may suggest otherwise. Given that the microarray field
is still growing, it will be interesting to see whether the array printer will
