Wednesday, March 01, 2006

Detecting Cocaine using DNA?

Saw a really cool story on today about using DNA molecules known as aptamers as sensors to detect cocaine. These "aptamers" are really cool. They are strands of DNA that fold up into specific shapes to bind particular molecules, with high specificity and selectivity. If you can find a way to reliably detect the binding event, then you can use them as sensors. The easiest way to do this seems to be by detecting the DNA folding in some manner.

There are a couple of reasons why aptamers are suited for sensors. 1 - they can be selected to bind specific molecules, and the selection process can be done by directed evolutionary synthesis. 2 - binding is reversible, you can wash away the substrate and repeat the binding many many times, making them suited for reusable sensors (always good for the cost conscious). 3 - you can easily determine the sequence of binding DNA molecules, which means you can easily make more. Once you know the sequence, you can make unlimited copies for use in just about any system you can imagine. 4 - you can couple them to many different types of sensors, electronic, optical or otherwise.

I really liked the story, because I actually did a seminar on using aptamers in sensors last fall, and actually looked at some publications by the same group that published the work. I think it's great to see the work on the front page of a technology news site. The best news is that the group is in licensing talks with companies about creating a commercial product. Hopefully this will pave the way for more applications. If you have access, the original publication is here.

So what's so great about this work? Well, they created a sensitive sensor (detects low levels of cocaine), that works really fast (takes about 4 mins), and can detect cocaine even in mixtures (good when people try to make it seem to be something else). And it's electronic, which makes it really easy to convert the signal and make it really small. Who knows, maybe we'll see more sensors of the same type for other analytes in the near future. Maybe even ones that can specifically analyze more than one analyte on the same chip? That would be cool.

By the way, you can also use aptamers for other things besides sensors. They are also being used as drugs for macular degeneration and cancer. Pretty neat little molecules.Science / Tech News_

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