Enzymes Encapsulated within Alginate Hydrogels: Bioelectrocatalysis and Electrochemiluminescence Applications

Area of Science:

• Biomaterials Science
• Analytical Chemistry
• Biotechnology

Background:

• Enzyme immobilization is crucial for developing stable and reusable biosensors.
• Alginate hydrogels offer a biocompatible matrix for enzyme encapsulation.
• Electrochemical detection methods provide sensitive and selective analyte quantification.

Purpose of the Study:

• To develop a simple procedure for immobilizing enzymes (HRP and LOx) within alginate hydrogels.
• To create stable and sensitive biosensors for detecting hydrogen peroxide and lactic acid.
• To evaluate the performance of the enzyme-immobilized hydrogels in real-world samples.

Main Methods:

• Enzyme immobilization onto CaCO3 microspheres followed by nanoshell deposition.
• Dispersion of microspheres into alginate solution and drop casting onto electrodes.
• Cross-linking using Ca2+ cations and characterization via cyclic voltammetry and ECL.
• Kinetic studies to determine apparent Michaelis-Menten constants.

Main Results:

• Enzymatic activity of HRP and LOx was well-maintained after immobilization.
• Apparent Michaelis-Menten constants were determined for HRP (7.71 ± 0.62 μM) and LOx (8.41 ± 0.43 μM).
• Biosensors exhibited good stability, repeatability, and low limits of detection (5.38 ± 0.05 μM for H2O2, 0.50 ± 0.03 μM for lactic acid).
• Stability of encapsulated enzymes was maintained for up to 28 days.
• Successful detection of analytes in real matrices (contact lens solution and artificial sweat).

Conclusions:

• The developed method provides a simple and effective way to immobilize enzymes in alginate hydrogels for biosensing applications.
• The alginate-encapsulated enzyme biosensors demonstrate high sensitivity, selectivity, and stability.
• This approach holds promise for the development of practical diagnostic tools for hydrogen peroxide and lactic acid detection.