A Highly Sensitive and Selective Fluorescein-Based Cu²⁺ Probe and Its Bioimaging in Cell

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Copper (Cu2+) is essential for biological processes but toxic at high levels.
• Sensitive detection methods for Cu2+ are crucial for environmental monitoring and biological research.
• Existing on-site Cu2+ detection methods lack sensitivity and selectivity.

Purpose of the Study:

• To design, synthesize, and characterize a novel fluorescent probe (N4) for selective Cu2+ detection.
• To evaluate the probe's performance for on-site analysis and biological imaging.
• To establish the interaction mechanism between the probe and Cu2+.

Main Methods:

• Fluorescent probe design and synthesis (N4).
• Spectroscopic analysis (fluorescence, UV-Vis) for Cu2+ detection.
• Selectivity, sensitivity, and pH range determination.
• Job's plot and mass spectrometry for interaction studies.
• Cellular imaging experiments.

Main Results:

• Probe N4 demonstrated high selectivity and sensitivity for Cu2+ over other metal ions.
• Naked-eye detection of Cu2+ was achieved via a visible color change at 525 nm.
• Linear response observed for Cu2+ concentrations from 0.1-1.5 eq. with a limit of detection of 1.20 μm.
• 1:1 interaction stoichiometry between N4 and Cu2+ confirmed.
• Probe N4 showed low cytotoxicity and was successfully used for Cu2+ imaging in living cells.

Conclusions:

• The novel fluorescein-based probe N4 is highly selective and sensitive for Cu2+ detection.
• N4 facilitates on-site, naked-eye, and cellular imaging applications for trace Cu2+ analysis.
• The probe's performance supports its potential for environmental monitoring and biomedical research.