Influence of pH on the Conformation of a Modified Aptamer to Nucleolin Protein

Abstract The search for agents for targeted delivery of anticancer drugs remains a crucial challenge for medicine. In this context, DNA aptamers targeting cancer cell-specific proteins have medical use. At the same time, additional fine-tuning of aptamer properties to diminish their affinity for potential target cells outside tumor tissues makes the aptamers promising tools in clinical applications due to reduced immunogenicity and fewer side effects. One of the approaches is to employ the deregulation of acidity in cancer cells and tissues. In this work, the AS1411 aptamer to nucleolin was modified by adding a nucleotide sequence to its binding site to create a pH-sensitive linker. UV melting and fluorescence methods were employed to demonstrate that the conformation of the new aptamer depends on pH of the medium.