AFM1 Detection in Milk by Fab' Functionalized Si₃N₄ Asymmetric Mach-Zehnder Interferometric Biosensors

Area of Science:

• Biophotonics
• Food Safety
• Analytical Chemistry

Background:

• Aflatoxins (AF) are toxic secondary metabolites produced by Aspergillus species.
• Aflatoxin M1 (AFM1) is a frequent and hazardous aflatoxin found in milk.
• EU regulations set maximum AFM1 levels in milk at 50 ppt for adults and 25 ppt for infants.

Purpose of the Study:

• To develop and evaluate a photonic biosensor for sensitive AFM1 detection in milk.
• To utilize asymmetric Mach-Zehnder Interferometers (aMZI) functionalized with Fab' for AFM1 detection.
• To enable real-time kinetic analysis of the Fab'-AFM1 interaction.

Main Methods:

• Fabrication of Si3N4 asymmetric Mach-Zehnder Interferometers (aMZI).
• Functionalization of aMZI with Fab' antibodies specific to AFM1.
• Detection of AFM1 in purified and concentrated milk samples using the functionalized biosensor.
• Real-time monitoring of ligand-analyte binding to study reaction kinetics.

Main Results:

• The aMZI-based biosensor demonstrated a minimum detectable concentration of 48 pM (16.8 pg/mL) for AFM1.
• The sensor provided real-time detection capabilities, allowing for kinetic studies.
• Kinetic rate constants for the Fab'-AFM1 interaction were successfully measured.

Conclusions:

• The developed photonic biosensor offers a sensitive and real-time method for AFM1 detection in milk.
• This technology has potential applications in food safety monitoring and ensuring milk product quality.
• The ability to study binding kinetics provides deeper insights into the detection mechanism.