Harnessing Cytosine for Tunable Nanoparticle Self-Assembly Behavior Using Orthogonal Stimuli.

Area of Science:

• Polymer Chemistry
• Supramolecular Chemistry
• Nanotechnology

Background:

• Nucleobases like cytosine are fundamental to biological systems due to specific hydrogen bonding.
• Synthetic polymers offer versatile platforms for creating novel materials with tailored properties.
• Combining nucleobases with synthetic polymers enables the design of responsive nanomaterials.

Purpose of the Study:

• To synthesize cytosine-containing nanoparticles using a controlled polymerization technique.
• To investigate the influence of pH on the self-assembly behavior and morphology of these nanoparticles.
• To explore the stability of the formed nanoparticles under varying pH and temperature conditions.

Main Methods:

• Aqueous reversible addition-fragmentation chain transfer polymerization-induced self-assembly (RA-FT-ISA) was employed.
• Poly(N-acryloylmorpholine) macromolecular chain transfer agent (mCTA) was chain-extended with cytosine acrylamide.
• Morphological phase diagrams were constructed, and small-angle X-ray scattering (SAXS) was used to analyze nanoparticle behavior.

Main Results:

• Cytosine-containing nanoparticles were successfully synthesized via RA-FT-ISA.
• Acidic conditions (low pH) induced cytosine dimerization, altering polymer self-assembly and nanoparticle morphology compared to neutral pH.
• Nanoparticle stability was effectively controlled by adjusting pH and temperature, with stable nanoparticles forming at longer polymer chain lengths under acidic conditions.

Conclusions:

• The study demonstrates the successful synthesis of responsive cytosine-containing nanoparticles.
• Hydrogen bonding of cytosine plays a crucial role in directing polymer self-assembly and nanoparticle formation.
• The pH and temperature-dependent control over nanoparticle morphology and stability opens avenues for advanced nanomaterial applications.