Synthesis and Properties of Upper Critical Solution Temperature Responsive Nanogels

Area of Science:

• Polymer Chemistry
• Materials Science
• Biotechnology

Background:

• Copolymers with pendent ureido and primary amino groups exhibit upper critical solution temperature (UCST) behavior.
• Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is a biocompatible, water-soluble polymer.

Purpose of the Study:

• To synthesize and characterize a novel temperature-responsive nanogel.
• To investigate the encapsulation and release capabilities of the nanogel for guest molecules.

Main Methods:

• Reversible addition-fragmentation chain-transfer (RAFT) radical polymerization was used to create a diblock copolymer.
• Postmodification reactions were employed to introduce functional groups and form micelles.
• Cross-linking of primary amines in the micelle core formed the nanogel.
• NMR and light-scattering techniques were used for characterization.

Main Results:

• The diblock copolymer PMPC$_{20}$P(U/A10)$_{165}$ exhibits UCST behavior, forming polymer micelles above the phase transition temperature (T$_{p}$).
• A cross-linked nanogel was formed with a temperature-dependent core that shrinks below T$_{p}$ and swells above T$_{p}$.
• The nanogel effectively encapsulated hydrophobic molecules and bovine serum albumin (BSA) below T$_{p}$ via hydrophobic interactions.

Conclusions:

• The synthesized nanogel demonstrates tunable swelling and shrinking behavior in response to temperature.
• The nanogel shows promise for controlled encapsulation and release of biomolecules, particularly BSA, above its T$_{p}$.