A Novel Approach for the Synthesis of Responsive Core-Shell Nanogels with a Poly(N-Isopropylacrylamide) Core and a...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Microgel particles are crucial in drug delivery, tissue engineering, biosensors, and biocatalysis.
• Amine-functionalized microgels offer pH responsiveness and chemical functionalities for bioconjugation and pollutant binding.
• Controlled synthesis of amine-functionalized microgels with specific architectures remains a challenge.

Purpose of the Study:

• To present a novel method for synthesizing responsive core-shell nanogels with poly(N-isopropylacrylamide) (pNIPAm) core and a polyamine shell.
• To demonstrate controlled incorporation of amine functionalities onto nanogel surfaces.
• To investigate the impact of polyamine shell on nanogel characteristics.

Main Methods:

• Synthesized surface-functionalized pNIPAm nanogels via semi-batch precipitation polymerization with acrylic acid.
• Coupled polyethyleneimine (PEI) to carboxyl functionalities on the nanogel surface using EDC.
• Varied EDC concentration, reaction temperature, and PEI molecular weight (0.6–750 kDa).
• Analyzed nanogel swelling and electrophoretic mobility as a function of pH and temperature.

Main Results:

• Successfully confined carboxyl functionalities to the outer shell of pNIPAm nanogels.
• Demonstrated efficient coupling of PEI to form a polyamine shell.
• Showed that PEI molecular weight significantly influences the immobilization of polyamine units.
• Confirmed the successful formation of the core-shell structure and its pH/temperature-dependent behavior.

Conclusions:

• Developed a general framework for controlled synthesis of core-shell nanogels with tunable surface properties.
• The method allows for precise control over amine functionality incorporation.
• These nanogels show potential for diverse applications in biomedicine and materials science.