Development of Click Nucleic Acids for Biosensing
University of Delaware
Herein, a new type of nucleic acid analog referred to as a ‘click nucleic acid’ (CNA) is described. Nucleic acids, such as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), as well as current analogs, such as peptide nucleic acid (PNA) and locked nucleic acid (LNA), have been used in many lab scale applications that leverage the complementarianism between two sequence specific strands of the polymer. Limitations of the current methods not only prevent widespread use in vivo due to enzymatic degradation and hydrolysis, but also are quite costly to scale up and utilize inefficient reactions to make these periodic polymers. The proposed CNA material that can overcome these issues is built using the same four nucleobases that are found in naturally occurring DNA with the naturally occurring phosphate-sugar backbone replaced with a neutral, primarily alkane backbone that could lead to tighter binding of complementary strands. The ‘click’ portion of its name refers to click chemistry, a subset of chemical reactions that are highly efficient and proceed under ambient conditions. This CNA material has the benefits of reusing excess monomer, efficient click chemistry, scale up, and cleaner purification. The synthesis of the four nucleotide mimicking monomers follows a four or five step synthetic pathway involving commonly employed organic reactions such as an alkylation, hydrolysis, reductive amination, and substitution/elimination. Subsequently, a solid phase synthesis protocol is outlined to provide sequence specific polymers using a protecting group strategy similar to typical Fmoc peptide synthesis. Initial results show that solubility is an issue that is preventing polymers larger than three units long from being both synthesized and characterized. In overcoming this challenge, a variation on the four nucleobase mimicking monomers has begun development that adds an extra carboxylic acid functionality to the backbone that should help with solubility.