Microplate differential calorimetric biosensor for ascorbic acid analysis in food and pharmaceuticals

Area of Science:

• Analytical Chemistry
• Biochemistry
• Biosensor Technology

Background:

• Ascorbic acid quantification is crucial in food and pharmaceuticals.
• Existing methods may lack speed, throughput, or cost-efficiency.
• Label-free, high-throughput quantification methods are desirable.

Purpose of the Study:

• To develop a label-free, low-volume, high-throughput microplate calorimetric biosensor for ascorbic acid.
• To investigate discrepancies in sensor readings using a mathematical model.
• To validate the biosensor's performance for real-world samples.

Main Methods:

• Development of a microplate differential calorimetry (MiDiCal) biosensor.
• Mathematical modeling of biochemical reactions and diffusion (oxygen, ascorbic acid, ascorbate oxidase).
• Calibration and validation against High-Performance Liquid Chromatography (HPLC).

Main Results:

• A novel biosensor for ascorbic acid quantification was successfully developed.
• Oxygen depletion was identified as a limiting factor in microliter volumes, impacting reaction rates.
• The sensor demonstrated a linear response from 2.4 to 350 mM ascorbic acid with a 0.8 mM limit of detection.
• Validation experiments showed good correlation with HPLC reference measurements.

Conclusions:

• The developed MiDiCal biosensor offers fast and accurate ascorbic acid quantification.
• Understanding oxygen diffusion is critical for optimizing microliter-scale enzymatic assays.
• The biosensor presents a cost-effective, high-throughput solution for food and pharmaceutical analysis.