A highly selective and sensitive in vivo fluorosensor for zinc(II) without cytotoxicity

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Materials Science

Background:

• Zinc ions (Zn2+) play crucial roles in biological processes.
• Dysregulation of Zn2+ is linked to various diseases, including cancer.
• Development of precise and sensitive Zn2+ detection methods is essential for biomedical research.

Purpose of the Study:

• To design and synthesize a novel fluorescent sensor for selective and sensitive detection of Zn2+.
• To evaluate the sensor's performance in terms of selectivity, sensitivity, and binding affinity.
• To assess the sensor's applicability for intracellular Zn2+ imaging in cancer cells.

Main Methods:

• Synthesis of 2,6-bis(2-hydroxy-benzoic acid hydrazide)-4-methylphenol (1) as a fluorescent probe.
• Characterization of the probe's complex formation with Zn2+ in aqueous THF at physiological pH.
• Spectroscopic analysis (fluorescence spectroscopy) to determine excitation/emission profiles and sensitivity.
• Evaluation of selectivity against other biologically relevant metal ions.
• Assessment of cell permeability and intracellular Zn2+ sensing in A375 human melanoma cancer cells.

Main Results:

• The synthesized probe (1) forms a 2:1 complex with Zn2+ at physiological pH.
• The sensor exhibits visible light excitation (390 nm) and emission (490 nm).
• Exceptional selectivity for Zn2+ over competing metal ions was observed.
• High sensitivity was demonstrated with a dissociation constant (Kd) < 1 pM and limit of detection (LOD) < 1 ng L(-1).
• A significant ~680-fold enhancement in fluorescence intensity upon Zn2+ binding was achieved.
• The probe demonstrated cell permeability and successful intracellular Zn2+ sensing in A375 human melanoma cancer cells.

Conclusions:

• The developed fluorescent sensor offers high selectivity and sensitivity for Zn2+ detection.
• The probe's properties make it suitable for real-time monitoring of Zn2+ in biological systems.
• The sensor's ability to perform intracellular Zn2+ sensing in cancer cells highlights its potential for cancer diagnostics and research.