Aptamers from Louisville

Nana Dadzie Ghansah
3 min readApr 23, 2020

By Nana Dadzie Ghansah

“SELEX” (Systematic Evolution of Ligands by EXponential enrichment)

We all know of DNAs and RNAs. They are the building blocks of our genome. We also know that both these nucleic acids are made up of nucleotides. There were those scientists who saw them as being more than just that.

One of them was a gentleman named Craig Tuerk. In 1990, he was working on the thesis for his PhD in Molecular, Cellular, and Developmental Biology at the University of Colorado in Boulder. He was working with the RNA of the bacteriophage T4 (bacteriophages are viruses that infect bacteria). Through a mutation process, he was able to capture 2 pieces of RNA, each 8 nucleotides long, from the 65,000-nucleotide bacteriophage RNA. He named the process “SELEX” (Systematic Evolution of Ligands by EXponential enrichment) and later published a paper about this with his mentor and professor of Molecular, Cellular, and Developmental Biology, Larry Gold.

Around the same time, Andy Ellington and Jack Szostak at MGH in Boston, working independently and using a similar technique, were able to generate pieces of RNA too. They called the pieces generated “aptamers” (from the Latin ‘aptus’ — fit, and Greek ‘meros’ — part) in their 1990 paper in “Nature”.

Now, why did this even matter?

Well, we all know RNAs and DNAs as substances that can store information. However, they also have the ability to bind to proteins. The ability to generate smaller versions allowed them to be used to bind to all manner of proteins…like antibodies do.

With that, the possibility of creating artificial antibodies was born.

Over the years, there has been a lot of development in the field of aptamers. They are being looked at for the treatment of cancer, a wide variety of other ailments as well as in the diagnosis and treatment of viral and bacterial diseases. This includes the creation of artificial antibodies against pathogens.

“Macugen“ is an RNA aptamer that was approved in 2004 as a drug to treat wet age-related macular degeneration.

One problem aptamers have faced is their rather quick clearance from circulation by enzymes. Another issue is the weakness of the bonds they form with proteins. Recent modifications have addressed those…

Nana Dadzie Ghansah

An anesthesiologist, photographer, writer, and poet. He lives and works in Lexington, Kentucky.