An Indole-based Chromofluorogenic Probe for Detection of Trivalent Al³⁺, Ga³⁺, In³⁺ and Fe³⁺ Ions

Area of Science:

• Chemical Sensing
• Molecular Probes
• Bioimaging

Background:

• Trivalent metal ion detection is crucial in environmental and biological systems.
• Development of selective and sensitive probes is essential for accurate sensing.
• Indole derivatives offer versatile platforms for designing chromofluorogenic sensors.

Purpose of the Study:

• To develop and characterize an indole-derived chromofluorogenic probe (InNS) for selective trivalent metal ion recognition.
• To investigate the sensing mechanism and binding interactions of InNS with target metal ions.
• To evaluate the practical applicability of InNS in biological samples and bioimaging.

Main Methods:

• UV-Vis and fluorescence spectroscopy for cation sensing studies.
• Job's plot, ¹H NMR, and DFT analysis for binding mode determination.
• Cell-based assays using MCF-7 cell lines for bioimaging applications.

Main Results:

• InNS exhibited a chromogenic response to Al³⁺, Ga³⁺, In³⁺, and Fe³⁺ with a visible color change.
• A selective 'turn-on' fluorescence response was observed exclusively for Al³⁺.
• The probe demonstrated a low detection limit (12.5 nM) and high association constant (6.85×10⁶ M^-1) for Al³⁺.
• A 1:1 binding mode between Al³⁺ and InNS was confirmed.
• InNS was successfully applied for Al³⁺ detection and bioimaging in MCF-7 cancer cell lines.

Conclusions:

• InNS is a highly effective and selective chromofluorogenic probe for Al³⁺ detection.
• The probe's 'turn-on' fluorescence and bioimaging capabilities highlight its potential in biological and medical diagnostics.
• The developed probe offers a promising tool for real-time monitoring of Al³⁺ in complex biological environments.