Combination of i-motif and G-quadruplex structures within the same strand: formation and application

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• DNA can form complex non-canonical structures beyond the double helix.
• G-quadruplexes and i-motifs are examples of such structures with potential applications.
• Controlling and integrating different DNA structures is a key challenge in molecular engineering.

Purpose of the Study:

• To construct a novel DNA nanostructure integrating both i-motif and G-quadruplex structures within a single oligonucleotide.
• To investigate the functional properties of this integrated double quadruplex.
• To explore its potential as a molecular logic gate.

Main Methods:

• Oligonucleotide synthesis to create a single strand capable of forming both i-motif and G-quadruplex structures.
• Spectroscopic techniques (e.g., fluorescence spectroscopy) to characterize the formed structures.
• Assays using crystal violet dye to demonstrate the logic gate functionality.

Main Results:

• Successfully synthesized and characterized a DNA molecule forming a stable double quadruplex (i-motif and G-quadruplex) in a single strand.
• Demonstrated that the double quadruplex structure exhibits distinct fluorescence properties.
• Showcased the structure's ability to function as a NOT logic gate, responding to specific conditions via fluorescence changes of crystal violet.

Conclusions:

• A novel DNA nanostructure featuring a coexisting i-motif and G-quadruplex within one strand was successfully created.
• This double quadruplex structure serves as a functional NOT logic gate.
• The findings open avenues for developing sophisticated DNA-based molecular devices and biosensors.