Tuning Microenvironment over Metal-Organic Frameworks for Efficient Enzyme Immobilization and Sensitive Immunoassay

Area of Science:

• Materials Science
• Biotechnology
• Nanotechnology

Background:

• Enzyme immobilization in metal-organic frameworks (MOFs) is crucial for enzyme stability in harsh conditions.
• However, suboptimal microenvironments within MOFs often reduce enzyme bioactivity and practical utility.

Purpose of the Study:

• To develop a functionalized hierarchically porous MOF (HP-MOF) carrier for efficient enzyme immobilization.
• To enhance the microenvironment within the MOF for improved enzyme performance and stability.
• To create a sensitive biosensor for chlorpyrifos detection using the immobilized enzyme.

Main Methods:

• Functionalized ligands were introduced into hierarchically porous MOFs (HP-MOFs) to tune the microenvironment.
• An acid etching strategy was employed to further enhance the mesoporous structure.
• Cytochrome c (Cyt c) was immobilized onto the functionalized HP-MOFs (HP-MOF-OH@Cyt c).
• A biosensor was constructed using HP-MOF-OH@Cyt c for chlorpyrifos detection.

Main Results:

• The HP-MOFs exhibited a pore size matching cytochrome c, allowing high loading (19.00%) and enzyme accessibility.
• Hydrophilic -OH functionalization preserved the secondary structure of Cyt c, boosting catalytic activity.
• The immobilized enzyme demonstrated excellent recyclability and tolerance to extreme conditions.
• The resulting biosensor showed a wide linear range (10–10,000 pg mL⁻¹) for chlorpyrifos detection with a low limit of detection (4.63 pg mL⁻¹).

Conclusions:

• Functionalized HP-MOFs provide an optimized microenvironment for enzyme immobilization, enhancing stability and activity.
• The developed HP-MOF-OH@Cyt c system is effective for creating robust and sensitive biosensors.
• This approach shows significant promise for practical enzyme-based applications, particularly in environmental monitoring.