Copyright 2011 Vista Therapeutics, Inc. | All Rights Reserved
The technology underlying Vista's NanoBioSensor could be
summed up this way: Microscopic nanowires are embedded into a
"chip" about an inch square. The chip is then "functionalized" by
attaching antibodies or other "capture" molecules to the various wires
within the chip. The chip is placed in the NanoBioSensor reader unit
(shown above), and a solution containing "target" molecules is then
pumped automatically or pipetted manually into and across the chip.
When the target molecules flow over nanowires coated with their
complementary molecule, they bind to the wire, changing the
conductivity of the wire. Changes in conductivity induce more or less
electrical current to flow through the wire (in correlation with the
concentration of the particular target molecule within the fluid). The
amount of current flowing through each wire is measured in real time
and displayed on a PC attached to the NanoBioSensor.
It should be noted that a typical molecular binding only lasts about seven seconds, but as more target molecules float by, they replace the previous ones, maintaining the same electrical flow through the wire. The only factor that changes the current and its subsequent measurement and display would be a change in concentration of the target molecule within the incoming solution. Thus, real-time monitoring is possible, given a fluid containing the molecule whose concentration one is interested in measuring (and possibly acting upon).
It should be noted that a typical molecular binding only lasts about seven seconds, but as more target molecules float by, they replace the previous ones, maintaining the same electrical flow through the wire. The only factor that changes the current and its subsequent measurement and display would be a change in concentration of the target molecule within the incoming solution. Thus, real-time monitoring is possible, given a fluid containing the molecule whose concentration one is interested in measuring (and possibly acting upon).
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Nanowires are microscopic electric wires whose
diameter can be as small as 10 nanometers or
less. The wires act as a Field Effect Transistor
(FET), a tiny "switch" with two circuits, one with a
small current flow (the gate), and the other with a
much greater flow. Electrical current changes in
the gate produce concomitant, amplified current
changes in the more powerful detector circuit.
That's what our NanoBioSensor measures in real
time.
The above micro-photo
actually shows a single virus
binding (and unbinding) from a
nanowire during
experimentation.
A single nanowire is a marvel (Nobel prize
nominated in fact), but a chip with hundreds of
wires is much more useful. The photo on the
right shows one of Vista's chips (which would be
functionalized with capture molecules of interest
and inserted into the NanoBioSensor). The red
boxes represent the approximate working area of
the chip. Vista will functionalize different chips for
different sets of molecules of interest.
The above schematic shows a
chip's structure, including its
inlet and outlet ports.
As a solution containing target molecules of interest flows
over the nanowires in the chip, the NanoBioSensor in which
the chip has been inserted records the electrical data and
sends it to our custom software, running on an ordinary PC.
The output on the left shows the results when wires,
functionalized with antibodies to prostate specific antigen
(PSA) responded to solutions containing various
concentrations of PSA. Bovine serum albumin (BSA) was
introduced as a control, and had no effect. (Relative rather
than absolute values count.) On the right are test results from
a 5-month old chip, which apparently still works.