Dr. Robert Curl
Development of a Whole Chip Imager for Biological Applications
At present, scanning imagers are used to monitor gene activity
by hybridization of dye-labeled c-DNA (or possibly RNA)
to complementary strands on the chip. This is approach is
also used to detect anomalies in nuclear or mitochondrial
DNA such as single nucleotide polymorphisms. Such anomalies
can also be detected by addition using polymerase of dye-labeled
terminator to the complementary strand on the chip.
These commercial scanning chip imagers operate by moving
the chip under the focused light from a laser collecting
the dye fluorescence into a microscope objective and at
each scanner step detecting the fluorescence typically with
an avalanche photodiode. The instrument under construction
differs in a fundamental way from these commercial instruments
that exist for the purpose of reading chips.
Work is underway at present to develop a DNA sequencing
methodology called sequencing-by-synthesis. In this approach,
a DNA fragment is hybridized to a complementary primer at
a site on the chip, then a variant form of polymerase adds
one uniquely dye-labeled terminating base of special structure.
The special structure allows the dye to be eliminated by
ultraviolet radiation and flushed away while converting
the terminator into a normal base ready to add the next
base in the sequence. The ability of the imager to monitor
the status of this photolysis process continually and rapidly
is essential for making the process work in a reasonable
amount of time. In contrast to scanning imagers, with the
new instrument the whole chip can be rapidly observed, which
can be a significant advantage in case something is amiss
with the chip.
Contact Information
|
