Fluorescence method for kanamycin detection based on the conversion of G-triplex and G-quadruplex

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• G-quadruplex DNA structures offer unique platforms for molecular sensing.
• Thioflavin T (ThT) is a fluorescent dye sensitive to G-quadruplex formation.
• Kanamycin detection in food is crucial for public health.

Purpose of the Study:

• To develop a novel fluorescence-based sensor for kanamycin detection.
• To utilize a G-quadruplex DNA scaffold with a kanamycin aptamer for enhanced fluorescence.
• To establish a sensitive and selective method for kanamycin determination in food matrices.

Main Methods:

• Construction of a G-quadruplex DNA scaffold by integrating a G31 sequence with a kanamycin aptamer.
• Utilizing thioflavin T (ThT) as a fluorescent reporter molecule.
• Employing a 'turn-on' to 'turn-off' fluorescence mechanism based on kanamycin binding to the aptamer-G-quadruplex structure.

Main Results:

• Significant enhancement of ThT fluorescence due to the planar G-quadruplex structure facilitating ThT binding.
• Kanamycin binding induced conformational changes in the G-quadruplex, leading to ThT dissociation and fluorescence quenching ('turn-off').
• Achieved a detection range of 50-2000 nM with a low limit of detection (1.05 nM).

Conclusions:

• The developed aptamer-G-quadruplex-ThT system provides a sensitive and selective platform for kanamycin detection.
• The method demonstrated successful application in the quantitative determination of kanamycin in real food samples (pork, chicken, beef).
• This approach offers a promising tool for food safety analysis and antibiotic residue monitoring.