The shape of DNA is one of those high school biology facts that is drilled into all student’s heads. Two strands with complementary base pairs will interact to form the long, winding shape of a helix. However, when there isn’t the second strand to form a helix with, single-stranded DNA will fold up in unique shapes (not unlike a protein!). These unnatural molecules of folded-up DNA are referred to as aptamers (from the Latin “aptus”, meaning “to fit”), and can be used to fit, or bind, onto other molecules. This sounds strange, but an example of how it works is shown below.
By folding around itself, a variety of loops and pockets form that can create a region that interacts with a scientist’s target of interest. Think of it as making a lock to fit a key!
What is the point in binding molecules with DNA? Multiple things, but two interesting examples are DNA biosensors and DNA therapeutics.
DNA Biosensors: A Sensible Application for Aptamers
A biosensor is just a fancy word for a sensor that uses a biological component to detect something. One that you undoubtedly know of is the dipstick-style test that analyzes urine to tell if you’re pregnant.
DNA biosensors have quickly moved from futuristic science to a proactive research field in just under three decades from their first proposal. In the past year alone, nearly one thousand scientific publications have been made furthering development and improvement of DNA biosensors!
One interesting use is a DNA biosensor made for cocaine detection: a specific DNA aptamer that glows normally, will go dark when mixed with extremely small concentrations of cocaine. This may sound like nothing more than a novelty, but the technology has been pushed further, with a dipstick-style test able to detect the presence of cocaine, even in blood, in under five minutes. While it’s hard to imagine scenarios where you yourself need to make a snap call that someone is using cocaine, with the incredibly short half-life of cocaine in the body, this could improve technology used by law enforcement agencies in the field. This is just one avenue, with biosensors detecting industrial pollutants, toxins, and other biomolecules becoming more commonplace.
DNA therapeutics are exactly what the name implies, using those folded up bits of DNA as a therapeutic medicine. Whereas “biologics” or engineered proteins for medicinal purposes are fairly common in biomedicine, DNA therapeutics are something many people are not aware exist. It’s an avenue of research constantly being explored, with several phase trials and one successful drug on the market already. The principal example is Macugen™. This drug, used to fight vision loss due to scar formation in the eye of patients with macular degeneration, is administered every 6 weeks. The Macugen™ aptamer binds to the protein responsible for telling your body to create blood vessels in the eye. When blood vessel formation in the eye goes unchecked in those afflicted, the degeneration is seen.
While this is still a fledgling field, the market has a demand for more efficient therapeutics, and curious scientists have a desire to see how far DNA function can be pushed. One step forward that is already being realized is the chemical modification of aptamers to make them act more like a protein, extending their properties to include reacting or changing the things they bind to.
DNA and Nanotechnology: Science Fiction Coming True
There is still much to learn about the applications for DNA. However, now that the groundwork has been laid out for scientists to start developing this technology, there has been an exponential growth in the creation of these biochemical tools. More hopeful still, with their attractive features and the interdisciplinary approach scientists take, DNA technology in many different forms is taking place. Here’s to the future.
About the author:
|Jeremy Duke is a Biochemistry and Molecular Biology PhD student at UGA, focusing on glycoconjugate vaccine development. He has a wonderfully eclectic music taste and likes to make costumes and read when there isn’t a pipette in hand. He can be contacted at firstname.lastname@example.org. More from Jeremy Duke.|