Self-assembled G-quadruplex nanostructures: AFM and voltammetric characterization.

Area of Science:

• Biotechnology
• Nanotechnology
• Biophysics

Background:

• G-rich oligodeoxynucleotides (ODNs) exhibit potential in medicine and nanotechnology due to their self-assembly capabilities into G-quadruplexes and nanostructures.
• Understanding the folding properties of specific ODN sequences is crucial for harnessing their nanotechnological applications.

Purpose of the Study:

• To investigate the folding properties and nanostructure formation of d(G)10, d(TG9), and d(TG8T) oligodeoxynucleotides.
• To correlate solution conditions (Na+, K+, incubation time) with the observed structures and electrochemical signals.

Main Methods:

• Atomic Force Microscopy (AFM) for visualizing nanostructures.
• Voltammetry at carbon electrodes for electrochemical detection of nucleotide folding states.
• Controlled variations in solution composition (Na+, K+) and incubation times.

Main Results:

• Single-stranded ODNs formed network films and polymeric structures, detected by AFM and guanine oxidation peaks via voltammetry.
• G-quadruplexes formed spherical aggregates (AFM) and showed altered voltammetry peaks (guanine and G-quartet) in Na+ (long incubation) or K+ solutions.
• d(G)10 uniquely formed G-nanowires (AFM); d(TG9) formed short, rod-like aggregates; d(TG8T) failed to form nanostructures due to terminal thymine residues.

Conclusions:

• The self-assembly of G-rich ODNs into distinct nanostructures is sequence-dependent and sensitive to environmental conditions.
• AFM and voltammetry are effective complementary techniques for characterizing ODN folding and nanostructure formation.
• Terminal modifications, like thymine residues in d(TG8T), can inhibit nanostructure assembly, offering insights for designing specific ODN-based nanomaterials.