A Fluoran-Based Cu²⁺-Selective Fluorescent Probe and its Application in Cell Imaging.

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Copper ions (Cu²⁺) are crucial in biological processes but toxic at high concentrations.
• Sensitive and selective detection methods for Cu²⁺ are needed for biological and environmental monitoring.
• Fluorescent probes offer advantages in sensitivity and real-time detection.

Purpose of the Study:

• To develop a novel fluorescent probe (FLACu) for selective Cu²⁺ detection.
• To investigate the sensing mechanism of FLACu towards Cu²⁺.
• To evaluate the applicability of FLACu for Cu²⁺ detection in living cells.

Main Methods:

• Synthesis of FLACu by modifying a fluoran skeleton with phenylhydrazine.
• Spectroscopic analysis (fluorescence) to study the probe's response to various metal ions.
• Determination of the limit of detection (LOD) and optimal pH range.
• Cellular imaging studies in living Hela cells to assess cytotoxicity and detection capability.

Main Results:

• FLACu demonstrated a specific "off-on" fluorescence response to Cu²⁺.
• The sensing mechanism involves Cu²⁺-induced spirolactam ring opening and hydrolysis.
• The LOD for Cu²⁺ was determined to be 35.4 nM within a pH range of 5.0-9.0.
• FLACu exhibited low cytotoxicity and was successfully used for detecting exogenous Cu²⁺ in living Hela cells.

Conclusions:

• FLACu is a highly selective and sensitive fluorescent probe for Cu²⁺ detection.
• The probe's mechanism is well-defined and relies on specific ion-induced chemical transformations.
• FLACu holds promise for real-time monitoring of Cu²⁺ in biological systems.