Label-Free Luminescent Switch-On Probe for Ochratoxin A Detection Using a G-Quadruplex-Selective Iridium(III) Complex

Area of Science:

• Coordination Chemistry
• Biophysical Chemistry
• Analytical Chemistry

Background:

• G-quadruplex DNA structures play roles in various biological processes.
• Developing selective probes for G-quadruplexes is crucial for biological research and diagnostics.
• Ochratoxin A (OTA) is a mycotoxin with potential health implications.

Purpose of the Study:

• To synthesize and evaluate luminescent iridium(III) complexes as G-quadruplex DNA probes.
• To develop a label-free sensing platform for ochratoxin A (OTA) using a selective G-quadruplex probe.
• To assess the sensitivity and selectivity of the developed OTA sensing platform.

Main Methods:

• Synthesis and characterization of six luminescent iridium(III) complexes.
• Investigation of the selectivity of iridium(III) complexes for G-quadruplex DNA structures.
• Construction of a label-free sensing platform utilizing the selective iridium(III) complex.
• Quantification of ochratoxin A (OTA) using the developed sensing platform and analysis of assay performance.

Main Results:

• One novel iridium(III) complex (complex 1) demonstrated high selectivity for G-quadruplex DNA.
• A label-free sensing platform for OTA was successfully constructed based on complex 1.
• The assay showed excellent linearity for OTA detection in the range of 0–60 nM (R2=0.9933).
• A low limit of detection (LOD) of 5 nM for OTA was achieved.
• The assay exhibited high selectivity for OTA against structurally similar analogues.

Conclusions:

• Luminescent iridium(III) complex 1 is a selective probe for G-quadruplex DNA.
• The developed label-free platform offers a sensitive and selective method for ochratoxin A detection in aqueous solutions.
• This approach holds promise for the development of diagnostic tools for mycotoxin analysis.