The Power of Old Hats: Rediscovering Inosine-EpPCR to Create Starting Libraries for Whole-Cell-SELEX

This new study by Grigory Bolotnikov, Ann-Kathrin Kissmann, Daniel Gruber, Andreas Bellmann and Frank Rosenau (Institute of Pharmaceutical Biotechnology, Ulm University, Germany) and Roger Hasler, Christoph Kleber, Wolfgang Knoll (DPU, Krems) brings renewed attention to a long-overlooked technique — error-prone PCR using inosine — as a surprisingly powerful way to create diverse molecular aptamer libraries. These short DNA sequences can be evolved in the laboratory to bind specific targets, such as bacteria or human cells, and have wide applications in diagnostics and therapeutics. Instead of relying on expensive, pre-made DNA libraries, the decision was made to start with a very simple DNA sequence using a low-cost method involving the nucleobase analogon inosine to introduce variation. The resulting libraries were then tested against ten very different targets, including beneficial and harmful bacteria as well as human cells. After only two rounds of selection, many of the resulting aptamers showed new and specific binding abilities — proving the method works. In essence, this work shows that older, simpler scientific tools — when applied creatively — can still solve modern problems. The key takeaway is that inosine-based error-prone PCR offers a cost-effective, accessible way to kickstart aptamer development, making it easier for more researchers to enter the field. Link to the article: https://doi.org/10.3390/bios15070448.