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Cambridge Immunology Network



Synthetic biology seeks to engineer biological processes. “Xenobiology” challenges us to go further, to construct and manipulate biological processes using artificial chemistries beyond those used by nature.

Nucleic acids (DNA and RNA) are capable of much more than just information storage; oligonucleotides can be used to design self-assembling nanoscale objects, but also (when single-stranded) can be evolved into an almost limitless variety of 3D structures, which include catalysts and ligands, also known as “aptamers” – short oligos that fold into chemical antibodies with affinity and specificity rivalling those of immunoglobulins.

Functional oligos have huge potential for precision medicine – they can be made to recognise, for example, membrane-bound proteins and sugars, targeting tumours or pathogens with remarkable specificity, and simply prepared on a desktop oligo synthesiser as you would a primer for PCR.

Unfortunately, natural chemistries present some serious hurdles: nucleases severely limit their stability in vivo, and their chemical uniformity impacts the type of interactions or mechanisms they can participate in.

Taking the learned lessons in medicinal chemistry during the development of antisense therapeutics, artificial oligo chemistries – or “xeno nucleic acids” (XNAs) – offer properties beyond those of DNA and RNA, such as reduced immunogenicity and nuclease-resistance in serum.

However, the inability of natural polymerase enzymes to use synthetic XNA building blocks has been a major barrier. By engineering polymerases to read and write using artificial chemistries, “synthetic genetics” has now become possible, enabling directed evolution of functional fully-modified XNA molecules.

We have established methods and proof-of-concept that biostable XNAs can be evolved into high affinity aptamers for specific targets, into a variety of catalysts or “XNAzymes”, and that XNAs can be designed to self-assemble into nanoscale polyhedra.

Xenobiology allows us to explore the fundamental requirements of life and how alternative biology might operate, but also has the potential to provide a wealth of new tools and technologies for research, industry and medicine. In my lab we are combining directed evolution, synthetic biology and bioengineering approaches to develop biomedical applications of XNAs.


Key publications: 

Arangundy-Franklin S … Taylor AI … Holliger P; A synthetic genetic polymer with an uncharged backbone chemistry based on alkyl-phosphonate nucleic acids; Nature Chemistry 2019; 10.1038/s41557-019-0255-4

Taylor AI, Houlihan, G. and Holliger P; Beyond DNA and RNA: the expanding toolbox of synthetic genetics , Cold Spring Harbour Perspectives in Biology 2019 (in RNA Worlds, eds. Cech TR, Steitz JA, Atkins FG, CSH Press); DOI: 10.1101/cshperspect.a032490

Taylor AI … Holliger P; Nanostructures from synthetic genetic polymers; ChemBioChem 2016; DOI: 10.7554/eLife.43022

Taylor AI … Holliger P; Catalysts from synthetic genetic polymers. Nature 2015; DOI: 10.1038/nature13982

Pinheiro VB, Taylor AI … Holliger P; Synthetic genetic polymers capable of heredity and evolution. Science 2012; DOI: 10.1126/science.1217622

Other Professional Activities

Together with researchers from the labs of Phillip Holliger and John Sutherland at the MRC Laboratory of Molecular Biology, I was involved in the creation of an exhibit for the 2019 Summer Science Festival at the Royal Society to showcase our work on nucleic acids and the chemical origins of life, called “A Recipe for Primordial Life”. The exhibit was shown at the Royal Society, various schools in Cambridge and London, and as part of “LifeLab” events at Ely Cathedral. Visitors were able to learn about geochemical processes on the early Earth 4 billion years ago, play an interactive game (available as an app through the website below) showing how simple chemicals can react to form some of the building blocks of life and learn about how scientists are exploring ways in which a primordial soup of these molecules may have given rise to the first living chemical systems or protocells. Visitors were also able to hear how this work deepens our understanding of the chemistry of nucleic acids and helps to pave the way for new types of medicine based on oligonucleotides, a key focus of my lab. 

 A website for the exhibition is here:


Royal Society video introduced by Prof. Brian Cox with interviews of some of the team:

Dr Alex  Taylor
Not available for consultancy


Person keywords: 
directed evolution
synthetic biology