Dr. David Rusling and his team at the University of Portsmouth have cracked open a new frontier in genetic recognition, using synthetic DNA letters to vastly expand the genetic code’s reach. For two decades, Rusling has pursued molecules that can precisely target DNA sequences, but it’s only now—with the integration of artificial bases—that his lab has achieved strong, selective binding under normal biological conditions. Their breakthrough, published in Nature Communications, introduces a toolkit that could reshape how scientists detect genes, repair DNA, and build nanoscale devices.
The challenge has long been one of access. Natural DNA consists of just four bases—A, T, C, and G—limiting the sequences that synthetic molecules like triplex-forming oligonucleotides (TFOs) can recognize. These TFOs, designed to bind double-stranded DNA, have historically worked only in narrow, acidic environments and could target only a fraction of possible genetic sequences. That severely restricted their use in medicine and diagnostics. Rusling’s innovation changes that by incorporating synthetic bases from an Artificially Expanded Genetic Information System (AEGIS), originally developed by the Benner laboratory in the U.S., which adds new "letters" to DNA’s alphabet.
By testing 120 different combinations of these expanded bases, the Portsmouth team identified a modular set of building blocks that allow TFOs to bind robustly at physiological pH—meaning they function in conditions mirroring the human body. This opens the door to real-world applications, from gene editing to disease detection. Even more promising, the system can recognize not just standard sequences but also damaged DNA, including oxidative lesions caused by normal cellular stress. These lesions are linked to aging, cancer, and neurodegenerative diseases, making their detection a critical diagnostic goal.
"This work expands the range of DNA sequences that can be recognized using TFOs," Rusling said. "By broadening the molecular recognition code and enabling strong binding under biologically relevant conditions, we have created a platform that other researchers can use to develop new tools for biotechnology and medicine." The team is now testing these synthetic molecules inside living cells, paving the way for targeted therapies and smart diagnostics.
What makes this advance especially powerful is its accessibility: the synthetic bases are commercially available, meaning labs worldwide can adopt and adapt the system. In a field often defined by complexity and exclusivity, this toolkit offers a rare combination of innovation and openness. As gene-targeting technologies evolve, this expanded genetic language may become a universal dialect—one that speaks not only to healthy DNA but also to its vulnerabilities.