Mushroom tyrosinase in polyelectrolyte multilayers as an optical biosensor for o-diphenols

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Materials Science

Background:

• Phenolic derivatives are crucial in medical, food, and environmental analysis.
• Tyrosinase biosensors offer advantages over traditional detection methods.
• Effective enzyme immobilization is key for biosensor development.

Purpose of the Study:

• To develop an ordered tyrosinase film using layer-by-layer (LbL) assembly for biosensor applications.
• To characterize the immobilized tyrosinase and its kinetic parameters.
• To evaluate the performance of the developed biosensor for L-DOPA detection.

Main Methods:

• Enzyme immobilization via LbL assembly, alternating tyrosinase with poly(dimethyldiallylammonium chloride).
• UV-vis spectroscopy to confirm enzyme loading.
• Spectrophotometric determination of kinetic parameters.
• Optical detection of L-DOPA using absorption and fluorescence spectroscopy.

Main Results:

• LbL deposition achieved high tyrosinase loading.
• Immobilized tyrosinase retained functionality and kinetic parameters were determined.
• The biosensor demonstrated good repeatability and time stability.
• Absorption-based assay: LOD of 23 µM, linear response up to 350 µM.
• Fluorescence-based assay: LOD of 3 µM, linear response in the tens of micromolar range.
• Sensitivity was tunable by adjusting the number of enzyme layers.

Conclusions:

• LbL assembly is an effective method for tyrosinase immobilization.
• The developed tyrosinase biosensor is suitable for sensitive and stable optical detection of L-DOPA.
• The biosensor's sensitivity can be modulated by controlling enzyme layer numbers, offering tunable detection capabilities.