Study of Quadruplex Nucleic Acids and Beyond

Dear Colleagues,

Non-canonical nucleic acids refer to structures that deviate from the classical Watson–Crick double helix of DNA and RNA. These include a wide range of alternative conformations formed by specific sequences and conditions, such as the following:

• G-quadruplexes (G4s)—guanine-rich sequences forming stacked G-tetrads stabilized by cations.
• i-Motifs—cytosine-rich DNA folding into intercalated structures at acidic pH.
• Z-DNA/RNA—left-handed helical forms of DNA or RNA.
• Triplex DNA—three-stranded DNA structures involving Hoogsteen or reverse Hoogsteen hydrogen bonding.
• Cruciforms, hairpins, and pseudoknots—structural motifs formed by palindromic or complementary intra-strand sequences.

These structures play important roles in the following processes:

• Gene regulation;
• Genome stability;
• Epigenetic control;
• RNA processing and translation.

Non-canonical nucleic acids are also emerging as targets for therapeutic intervention, biomolecular sensing, and nanotechnology due to their unique folding properties and biological relevance.

This Special Issue presents a comprehensive overview of recent advances in the study of non-canonical nucleic acids. It highlights the expanding understanding of their biological functions, structural diversity, and mechanistic roles in cellular processes, as well as discussing the current efforts focused on developing innovative chemical probes, nanomaterials, and biosensors.

Prof. Dr. Yan Xu
Guest Editor

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