Smart dual T₁ MRI-optical imaging agent based on a rhodamine appended Fe(III)-catecholate complex.

Area of Science:

• Biomedical Imaging
• Molecular Probes
• Nanotechnology

Background:

• Developing dual-modal imaging probes is crucial for comprehensive biological system analysis.
• Iron(III)-catecholate complexes offer unique properties for imaging applications.
• Rhodamine derivatives are valuable for optical imaging and sensing.

Purpose of the Study:

• To report a novel dual-modal T1 MRI-optical imaging probe, Fe(RhoCat)3.
• To evaluate the probe's performance in detecting nitric oxide (NO) and acidic pH.
• To assess the probe's potential for visualizing the tumor microenvironment.

Main Methods:

• Synthesis and characterization of the Fe(RhoCat)3 complex.
• Relaxivity measurements at varying magnetic field strengths and conditions.
• Optical imaging studies in vitro and in cells.
• Evaluation of probe response to nitric oxide and pH changes.

Main Results:

• Fe(RhoCat)3 demonstrated T1 MRI contrast with a relaxivity of 4.37 mM-1 s-1, enhanced to 7.09 mM-1 s-1 with bovine serum albumin.
• The rhodamine moiety enabled sensitive optical detection of nitric oxide and acidic pH.
• Probe relaxivity increased to 5.19 mM-1 s-1 upon NO interaction.
• Fe(RhoCat)3 successfully visualized nitric oxide in gastric cancer cells with high viability.

Conclusions:

• Fe(RhoCat)3 serves as a smart dual-modal T1 MRI-optical imaging probe.
• The probe exhibits "MRI-ON and Fluorescence-ON" characteristics for NO and acidic pH detection.
• Fe(RhoCat)3 holds potential for molecular imaging in the tumor microenvironment.