Magnetically Recoverable δ‑FeOOH Particles for Multilayer Enzyme Immobilization and Surface-Induced Activity Tuning

Area of Science:

• Biocatalysis and Enzyme Engineering
• Materials Science for Biotechnology
• Nanotechnology in Enzyme Applications

Background:

• Enzyme stability is crucial for biocatalysis but often limited.
• Conventional enzyme supports struggle with high loading and cost-effectiveness.
• A need exists for supports offering high surface area, easy recovery, and low production cost.

Purpose of the Study:

• To develop a novel, low-cost, magnetically recoverable support material for enzyme immobilization.
• To investigate the impact of the support on enzyme loading, activity, and structural integrity.
• To explore the potential of the support in enhancing enzymatic performance.

Main Methods:

• Synthesis and characterization of superparamagnetic δ-FeOOH (feroxyhyte) particles.
• Immobilization of lipase and NADH oxidase (LpNOX) onto δ-FeOOH.
• Enzyme activity assays and structural analysis using circular dichroism and fluorescence spectroscopy.
• Zeta potential analysis to study surface adsorption and multilayer formation.

Main Results:

• δ-FeOOH enabled lipase immobilization at loadings >60 mg g⁻¹, maintaining activity and structural integrity.
• Support-induced conformational changes (decreased α-helicity, increased β-sheet) did not impair enzyme performance.
• Zeta potential confirmed multilayer formation and continued adsorption beyond ~40 mg g⁻¹ without functional decline.
• Both immobilized lipase and LpNOX showed up to 1.3-fold activity enhancement, suggesting surface-induced activation.

Conclusions:

• δ-FeOOH is a high-capacity, structurally tunable enzyme support material.
• The material effectively enhances enzyme activity and stability, overcoming limitations of conventional supports.
• δ-FeOOH presents a promising platform for next-generation biocatalysts, including high-density and multienzyme systems.