Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

Area of Science:

• Polymer Chemistry
• Biomaterials Science
• Supramolecular Chemistry

Background:

• Polymer-peptide conjugates offer tunable properties for advanced applications.
• Elastin-like peptides (ELPs) provide biocompatibility and self-assembly characteristics.
• Controlled polymerization techniques are essential for synthesizing well-defined block copolymers.

Purpose of the Study:

• To synthesize poly(acrylic acid)-based diblock and triblock copolymers conjugated with elastin-like peptides.
• To investigate the self-assembly behavior of these polymer-peptide conjugates in aqueous solutions.
• To elucidate the key molecular interactions driving the self-assembly process using experimental and computational methods.

Main Methods:

• Synthesis of azide-functionalized poly(tert-butyl acrylate) (PtBA) via atom transfer radical polymerization (ATRP).
• Copper-catalyzed azide-alkyne cycloaddition (click chemistry) to conjugate PtBA with bis-alkyne-functionalized ELPs.
• Deprotection to yield poly(acrylic acid) (PAA)-ELP block copolymers.
• Characterization of aggregate formation using dynamic light scattering (DLS) and transmission electron microscopy (TEM).
• Coarse-grained molecular modeling to analyze inter- and intramolecular interactions and thermodynamic stability.

Main Results:

• Efficient synthesis of PAA-ELP diblock and triblock copolymers was achieved.
• Addition of phosphate-buffered saline (PBS) to dimethylformamide solutions induced the formation of polydisperse spherical aggregates.
• DLS and TEM confirmed the presence and morphology of these self-assembled structures.
• Molecular modeling identified hydrogen bonding between PAA chains and between PAA and ELP as the primary driving force for self-assembly and stabilization.

Conclusions:

• Polymer-peptide conjugates based on PAA and ELPs can be effectively synthesized and exhibit self-assembly into spherical aggregates.
• Hydrogen bonding interactions are crucial for the conformational stability and self-assembly of these block copolymers.
• The findings provide insights into the design of functional block copolymers for potential applications in drug delivery and tissue engineering.