Dual on-off and off-on switchable oligoaziridine biosensor

Area of Science:

• Polymer Chemistry
• Biomaterials Science
• Analytical Chemistry

Background:

• Development of sensitive and selective biosensors is crucial for environmental monitoring and biomedical diagnostics.
• Aziridine-based polymers offer unique properties for creating functional materials.
• Supercritical carbon dioxide provides a green and efficient medium for polymer synthesis.

Purpose of the Study:

• To synthesize a water-soluble, biocompatible aziridine-based biosensor.
• To investigate the sensor's binding capabilities with various metal ions.
• To evaluate the sensor's performance in aqueous solutions and living cells.

Main Methods:

• Radical polymerization of N-substituted aziridines in supercritical carbon dioxide.
• Fluorescence spectroscopy to monitor metal ion binding.
• Immunofluorescence microscopy for cellular imaging.
• Job plot analysis to determine binding stoichiometry.

Main Results:

• The synthesized biosensor demonstrated dual "off-on" and "on-off" fluorescence responses to metal cations.
• Zinc ions induced the highest fluorescence enhancement (turn-on), while copper ions caused the highest quenching (turn-off).
• The sensor showed high sensitivity (1.6 nM detection limit), selectivity, and reversibility for copper ions in living human fibroblast cells.

Conclusions:

• The aziridine-based biosensor is a promising tool for sensitive and selective detection of metal ions.
• Its biocompatibility and performance in physiological conditions make it suitable for cellular imaging.
• The dual response mechanism offers versatility for different sensing applications.