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>>Lu: We are actually very interested in the
interface between chemistry and biology and also the application of such interest
development in terms of fundamental research.
So on one hand we really want to take advantage of the chemical tools that are available
so we can actually look into biological targets.
At the same time we wanted to take advantage of recent technology and developments and
concepts from biology; inspired from the biology and do better chemistry.
What we really have been interested in doing is using DNA as a starting material.
where we have been able to utilize that to make all kinds of structures.
And then we can decorate that structure with different kinds of nano-materials.
The most important advantage of using DNA as a sensor is that they can actually
cover a wide range of targets.
For example, small molecules like metal ions, some toxic targets, and, obviously,
DNA is biocompatible biodegradable.
So it is actually non-polluting to the environment. It is very environmentally friendly.
So far our applications have focused mainly on environmental monitoring;
particularly toxic metal ion detection. Also the detection of organic contaminants
in the environment.
>>Wang: What we can detect is a variety of targets.
For example lead, uranium, as well as the small molecules such as cocaine or adenosine.
It is quite a powerful technology.
Here is a solution of gold nano-particles. This is made of nano scale sized
gold nano-particles.
It shows a red color.
We combine these nano-particles with the functional DNA and I want to make a
sensor out of it.
We're going to show the addition of some targets.
Here it gives an instant color-change.
So, by seeing this color change, we will know how many targets are in it and we can
make a biosensor out of it.
Here is the comparison.
Before and after the addition of the targets.
We see this huge color transition.
Biosensor detection by seeing color-change.
Lu: So what we have in here, although it is
colorless right now, is we have placed the DNA with gold particles right here.
So you dip this into a solution.
If there are no such targets, these DNA gold nano-particles will not have any reaction,
there is no change of color, and they stay in this particular place.
But, if there is a target in here, there will be specific changes. A chemical reaction occurs.
The DNA gold nano-particles will be disrupted, and will migrate through it and then there
will be a change of color.
So that something like this occurs.
And there be color changes in there.
And, based on whether the color changes, where it migrates through it,
in the few minutes, one can actually have side by side quantifiable information
about whether the food is safe to eat, the water is safe to drink,
or whether one has a disease in their urine or blood or not.
Most people are very familiar with the double helix.
When two DNA are put together they form a double helix in the process called hybridization.
So, in the absence of the target, those two pieces of DNA will be
hybridized together and then there would be minimal or no fluorescent signal.
In the presence of a target like lead or uranium, the metal comes in and then cleaves,
like a scissors, cuts the DNA into two pieces and one piece flies off
and then gives you the increase of fluorescent signals.
>>Xiang: What I will show is using fluorescence
to detect a target by DNA.
So here I have a few samples. So we can first start with a sample without lead.
And you will see the fluorescent signal is very weak.
We put it in the fluorometer.
The sample is in. We just need to operate The software to detect it.
This is the intensity for our blank sample.
It's like 400,000.
Okay, remember its value.
Now we do another sample with some lead.
We put this back in the fluorometer. Pretty simple, right?
Now for the sample with some lead. We get a similar curve, but the intensity is
much, much higher. It is now about 4 million.
So, in this sample, the fluorescence intensity is ten times that of our blank sample.
So, with some lead, you will see a ten times increasing of fluorescence.
>>Lu: This is the latest product that has been
developed based on our technology from Beckman and the University of Illinois
that we worked on together with a local start-up company called ANDalyze.
So this is a portable fluorometer.
This is the cartridge that contains inside the sensor that we developed.
And then, all you do is put it in here...
and then put in a sample of a solution of interest...
and push through here...
and then take it off...
and close it...
and push start.
And then, in about two minutes, you can get a reading of the sample
and its concentration. In this case it is lead.
The principle behind this particular meter is based on fluorescence.
Where the DNA will be, in the presence of the target,
it will cleave the DNA, release the fluorofor,
and then you have an increase in fluorescent signals.
This same technology can be applied; with just a simple change of the software behind it
we can develop this same product for detection of organic contaminants such as
diseases, bacteria, viruses, and so on and so forth.
We have already demonstrated that we can detect simple metal ions, toxic metals like mercury
and uranium and copper.
And also we can detect many other things like recreational drugs and pharmaceutical drugs
and also diseases; many of kinds of cancer and other diseases.
So the potential is huge because not only is it
very simple, very accurate, but also
it can be applied for many different varieties of targets that interest a lot of people.
Every day there is a new discovery happening,
and then new ideas,
and then being able to see your idea, being able to realize it in your own lab,
and with a really fantastic group of students and post docs, so really, I think, both the
education as well as the research products, that is what really excites me.
I think with the interface of more than one field, mostly chemistry and biology, but also
materials science and engineering, so what we really want to do is to
get inspiration from each area and we want to
have a combined benefit of all the fields
that we will be able to take advantage of.
So the end result is not only the new advances in each of the fields, in terms of fundamental
knowledge. But, more importantly, at the new applications and new products coming out
of this that actually people can use to be able to change their lives.
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