Temperature-Invariant Aqueous Microgels as Hosts for Biomacromolecules

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Enzyme Engineering

Background:

• Enzyme immobilization on solid supports enhances enzyme reusability, stability, and performance.
• Developing thermo-stable supports is crucial for enzymes used in high-temperature reactions.

Purpose of the Study:

• To synthesize and characterize poly(N-hydroxyethyl acrylamide) (PHEAA) microgels as thermo-stable carriers for enzymes.
• To evaluate the immobilization of horseradish peroxidase (HRP) onto PHEAA microgels and assess its activity and stability.

Main Methods:

• Two-step synthesis of PHEAA microgels using poly(diethylene glycol-ethyl ether acrylate) (PDEGAC) as a precursor.
• Aminolysis reaction to introduce primary amino groups for bioconjugation.
• Enzyme immobilization via EDC coupling and bis-aryl hydrazone (BAH) coupling.
• Dynamic laser scattering for colloidal stability assessment.
• Enzyme activity and thermal stability assays.

Main Results:

• PHEAA microgels maintained colloidal stability in water up to 100 °C.
• Characterization revealed approximately 9 mol % of primary amino groups for bioconjugation.
• Immobilized HRP retained high catalytic activity (87% for EDC, 96% for BAH).
• Microgel-supported HRP showed significantly enhanced thermal stability compared to free HRP.

Conclusions:

• PHEAA microgels are effective thermo-stable supports for enzyme immobilization.
• The developed microgels offer a promising platform for enzymatic reactions at elevated temperatures.
• Enzyme immobilization on PHEAA microgels enhances stability and preserves catalytic function.