Artificial Modified Nucleotides for the Electrochemical Detection of Nucleic Acid Amplification Products

Abstract

The review describes the fundamental electrochemical properties of nucleic acids manifested on solid electrodes, with an emphasis on the spatial structure of macromolecules. The formation of the double helix impedes the contact of the electroactive groups of the nitrogenous bases with the electrode surface, resulting in the disappearance of the analytical signal of deoxyribonucleic acid (DNA). The insufficient electroactivity of the double-stranded DNA is overcome by introducing electrochemically active fragments into the nucleic acid sequence through the polymerase incorporation of chemically modified nucleotides. Currently, an extensive range of artificial nucleotides has been synthesized, which contain various electroactive groups capable of both oxidation and reduction on electrode surfaces at different potentials. Artificial modified nucleotides must exhibit high electrochemical activity while also serving as good substrates for enzymes (polymerases) involved in nucleic acid amplification reactions. Introducing modified nucleotides instead of natural ones into polymerase reactions represents a compromise between the number of labels inserted in one amplicon and the length and quantity of the resulting products. Modified nucleotides find application in the detection of gene mutations and single-nucleotide polymorphisms, nucleic acid sequencing, determination of protein and peptide concentrations, and the detection of pathogenic viruses and bacteria. With the advancement of isothermal amplification methods, the development, synthesis, and investigation of artificial nucleotides have become highly relevant for creating new off-laboratory electrochemical nucleic acid analyzers.