Bifunctional starch nanoparticles for achieving recyclable interfacial biocatalysis within a narrow pH range

Area of Science:

• Biocatalysis
• Materials Science
• Green Chemistry

Background:

• Pickering interfacial biocatalysis (PIB) faces challenges due to pH incompatibility between enzyme activity and catalyst recovery.
• Traditional methods require harsh acidic conditions for emulsion destabilization, leading to enzyme deactivation.

Purpose of the Study:

• To design and synthesize novel bifunctional starch nanoparticles for efficient and recyclable PIB.
• To overcome the pH mismatch issue in enzyme-catalyzed reactions using Pickering emulsions.

Main Methods:

• Sequential TEMPO-mediated oxidation and graft copolymerization of starch nanoparticles with pH-responsive PDMAMA.
• Characterization of nanoparticle properties using interfacial analysis (zeta potential, contact angle, interfacial tension).
• Immobilization of Candida antarctica lipase B (CalB) for esterification reactions.

Main Results:

• Optimized bifunctional nanoparticles achieved reversible, pH-triggered emulsion breakdown (pH 6-8), compatible with enzyme activity.
• The system demonstrated cooperative ionization and buffering effects for enhanced pH sensitivity.
• CalB immobilized on nanoparticles achieved 97% conversion in esterification.
• Catalyst recovery and reuse over eight cycles with >80% activity retention was achieved via simple pH switching.

Conclusions:

• Developed a sustainable, starch-based strategy for recyclable biocatalysis using bifunctional nanoparticles.
• The pH-triggered system offers a greener and more economical approach to PIB by avoiding enzyme deactivation.
• This method advances the operational simplicity and efficiency of Pickering emulsion microreactors.